View source for Template:List of oxidation states of the elements

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{{Legend|{{element color|noble gas}}|Noble gas}}
{{Legend|white|text='''+1'''|Bold values are '''main oxidation states'''}}
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! colspan=20 | {{navbar-collapsible|Oxidation states of the elements|Template:List of oxidation states of the elements}}
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! colspan="3" rowspan="2" | Element 
! colspan="5" | Negative states 
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! colspan="9" | Positive states 
! rowspan="2" | [[Group (periodic table)|Group]]
! rowspan="2" | Notes
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! style="background:#d5e6f7" | −5
! style="background:#dfdfdf" | −4
! style="background:#ffc0cb" | −3
! style="background:#ffecd3" | −2
! style="background:#f5deb3" | −1
! style="background:#e0ffff" | 0
! style="background:#ffa07a" | +1
! style="background:#ffdead" | +2
! style="background:#ffbffe" | +3
! style="background:#cbcbcb" | +4
! style="background:#cccc98" | +5
! style="background:#a0fec2" | +6
! style="background:#e6fe8e" | +7
! style="background:#d1ddff" | +8
! style="background:#c6dd9d" | +9
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<!--- Period 1 --->
{{List of oxidation states of the elements/row|symbol=H|os= -1b, +1b|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row|symbol=He|os= |ref= |note= |datacheck=yes }}
<!--- Period 2 --->
{{List of oxidation states of the elements/row|symbol=Li|os= 0, +1b 
|ref=<!--
--><ref name="G&E Lithides"/><!--
--><ref>Li(0) atoms have been observed in various small lithium-chloride [[Atom cluster|clusters]]; see {{cite journal |first1=Milan |last1=Milovanović |first2=Suzana |last2=Veličković |first3=Filip |last3=Veljkovićb |first4=Stanka |last4=Jerosimić |title=Structure and stability of small lithium-chloride Li<sub>n</sub>Cl<sub>m</sub><sup>(0,1+)</sup> (n ≥ m, n = 1–6, m = 1–3) clusters |journal=Physical Chemistry Chemical Physics |issue=45 |date=October 30, 2017 |doi=10.1039/C7CP04181K |url=https://pubs.rsc.org/en/content/articlelanding/2017/cp/c7cp04181k}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row|symbol=Be|os= 0, +1, +2b 
|ref=<!--
--><ref name=ZeroValentBeryllium>Be(0) has been observed; see {{cite web |title= Beryllium(0) Complex Found |url= https://www.chemistryviews.org/details/news/9426001/Beryllium0_Complex_Found.html |publisher= [[Chemistry Europe]] |date= 13 June 2016}}</ref><!--
--><ref>Be(I) has been observed in [[beryllium monohydride]] (BeH); see {{cite journal|url=http://bernath.uwaterloo.ca/media/252.pdf |title=Infrared Emission Spectra of BeH and BeD |access-date=2007-12-10 |journal=J. Chem. Phys. |last1=Shayesteh |first1=A. |last2=Tereszchuk |first2=K. |last3=Bernath |first3=P. F. |last4=Colin |first4=R. |volume=118 |issue=3 |year=2003 |page=1158 |doi=10.1063/1.1528606 |url-status=dead |archive-url=https://web.archive.org/web/20071202130342/http://bernath.uwaterloo.ca/media/252.pdf |archive-date=2007-12-02 |bibcode=2003JChPh.118.1158S}} and in [(CAAC)<sub>2</sub>Be]<sup>+•</sup> [CAAC = cyclic (alkyl)(amino)carbene], see {{cite journal|url=https://pubs.acs.org/doi/10.1021/jacs.9b13777 |title=A Stable, Crystalline Beryllium Radical Cation |access-date=2020-11-17 |journal=J. Am. Chem. Soc. |last1=Wang |first1=Guocang |last2=Walley |first2=Jacob E. |last3=Dickie |first3=Diane E. |last4=Pan |first4=Sudip |last5=Frenking |first5=Gernot |last6=Gilliard Jr. |first6=Robert G. |volume=142 |issue=10 |year=2020 |pages=4560–4 |doi=10.1021/jacs.9b13777|pmid=32088963 |s2cid=211262005 }}</ref>}}
{{List of oxidation states of the elements/row |symbol=B  |os= −5, −1, 0, +1, +2, +3b
|ref=<!--
--><ref>B(−5) has been observed in Al<sub>3</sub>BC, see {{cite news|url=https://d-nb.info/995006210/34|first1=Melanie|last1=Schroeder|title=Eigenschaften von borreichen Boriden und Scandium-Aluminium-Oxid-Carbiden|page=139|language=de}}</ref><!--
--><ref>B(−1) has been observed in [[magnesium diboride]] (MgB<sub>2</sub>), see {{cite book|url=https://books.google.com/books?id=2RgbAgAAQBAJ&pg=PA315|title=Chemical Structure and Reactivity: An Integrated Approach|first1=James|last1=Keeler|first2=Peter|last2=Wothers|publisher=Oxford University Press|year=2014|isbn=9780199604135}}</ref><!--
--><ref>B(0) has been observed in [[diboryne]]s, see {{cite journal|doi=10.1126/science.1221138|title=Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond|year=2012|last1=Braunschweig|first1=H.|last2=Dewhurst|first2=R. D. |last3=Hammond|first3=K.|last4=Mies|first4=J.|last5=Radacki|first5=K.|last6=Vargas|first6=A.|journal=Science|volume=336|issue=6087|pages=1420–2|pmid=22700924|bibcode=2012Sci...336.1420B|s2cid=206540959}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=C  |os= −4b, −3b, −2b, −1b, 0b, +1b, +2b, +3b, +4b
|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=N  |os= −3b, −2, −1, 0, +1, +2, +3b, +4, +5b
|ref=<!--
--><ref>[[Tetrazoles]] contain a pair of double-bonded nitrogen atoms with oxidation state 0 in the ring. A Synthesis of the parent 1H-tetrazole, CH<sub>2</sub>N<sub>4</sub> (two atoms N(0)) is given in Ronald A. Henry and William G. Finnegan, "An Improved Procedure for the Deamination of 5-Aminotetrazole", _J. Am. Chem. Soc._ (1954), 76, 1, 290–291,
https://doi.org/10.1021/ja01630a086.</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=O  |os= −2b, −1, 0, +1, +2|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=F  |os= −1b,0|ref=<!--
--><ref>[[Gold heptafluoride]] is calculated to be the pentafluoride with a molecular F<sub>2</sub> ligand. {{cite journal|first1=Daniel |last1=Himmel |first2=Sebastian |last2=Riedel |title=After 20 Years, Theoretical Evidence That 'AuF<sub>7</sub>' Is Actually AuF<sub>5</sub>•F<sub>2</sub> | journal=Inorganic Chemistry |volume=46 |issue=13 |pages=5338–5342 |date=2007 | doi=10.1021/ic700431s|pmid=17511450 }}</ref><!--
--><ref>A cluster of elusive SF<sub>6</sub><sup>+</sup> with [[Helium compounds#Known ions|helium atoms]] is known to have fluorine(0)atom as a ligand; see {{Cite journal|last1=Albertini|first1=Simon|last2=Bergmeister|first2=Stefan|last3=Laimer|first3=Felix|last4=Martini|first4=Paul|last5=Gruber|first5=Elisabeth|last6=Zappa|first6=Fabio|last7=Ončák|first7=Milan|last8=Scheier|first8=Paul|last9=Echt|first9=Olof|date=2021-04-22|title=SF 6 + : Stabilizing Transient Ions in Helium Nanodroplets|url=https://pubs.acs.org/doi/10.1021/acs.jpclett.1c01024|journal=The Journal of Physical Chemistry Letters|volume=12|issue=17|language=en|pages=4112–4117|doi=10.1021/acs.jpclett.1c01024 |pmc=8154854|pmid=33886323|issn=1948-7185|doi-access=free}}</ref>|note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ne |os=|ref= |note= |datacheck=yes }}
<!--- Period 3 --->
{{List of oxidation states of the elements/row |symbol=Na |os= −1, 0, +1b
|ref=<!--
--><ref name="G&E Lithides">Na(−1), K(−1), Rb(−1), and Cs(−1) are known in [[alkalides]]; the table by Greenwood and Earnshaw shows −1 only for Na and also erroneously for Li; no lithides are described.</ref><!--
--><ref>The compound [[NaCl]] has been shown in experiments to exists in several unusual [[stoichiometry|stoichiometries]] under high pressure, including Na<sub>3</sub>Cl in which contains a layer of sodium(0) atoms; see {{Cite journal |last1=Zhang |first1=W. |last2=Oganov |first2=A. R. |last3=Goncharov |first3=A. F. |last4=Zhu |first4=Q. |last5=Boulfelfel |first5=S. E. |last6=Lyakhov |first6=A. O. |last7=Stavrou |first7=E. |last8=Somayazulu |first8=M. |last9=Prakapenka |first9=V. B. |last10=Konôpková |first10=Z. |year=2013 |title=Unexpected Stable Stoichiometries of Sodium Chlorides |journal=Science |volume=342 |issue=6165 |pages=1502–1505 |arxiv=1310.7674 |bibcode=2013Sci...342.1502Z |doi=10.1126/science.1244989 |pmid=24357316|s2cid=15298372}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Mg |os= 0, +1, +2b
|ref=<!--
--><ref>[[Low valent magnesium compound]]s with Mg(I) have been obtained using bulky ligands; see {{cite journal|last= Green|first= S. P. |author2=Jones C. |author3=Stasch A.|date=December 2007|title= Stable Magnesium(I) Compounds with Mg-Mg Bonds|journal= Science|volume= 318|issue= 5857|pages= 1754–1757|doi= 10.1126/science.1150856|pmid= 17991827|bibcode= 2007Sci...318.1754G|s2cid= 40657565 }}</ref><ref>Mg(0) has been synthesized in a compound containing a Na<sub>2</sub>Mg<sub>2</sub><sup>2+</sup> cluster coordinated to a bulky organic ligand; see {{cite journal |first1=B. |last1=Rösch |first2=T. X. |last2=Gentner |first3=J. |last3=Eyselein |first4=J. |last4=Langer |first5=H. |last5=Elsen |first6=W. |last6=Li |first7=S. |last7=Harder |title=Strongly reducing magnesium(0) complexes |doi=10.1038/s41586-021-03401-w |journal=Nature |volume=592 |year=2021 |issue=7856 |pages=717–721 |pmid=33911274 |bibcode=2021Natur.592..717R |s2cid=233447380 |postscript=none}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Al |os= −2, −1, 0, +1, +2, +3b
|ref=<!--
--><ref>Al(II) has been observed in [[aluminium(II) oxide]] (AlO); see {{cite journal |first1=D.C. |last1=Tyte |title=Red (B2Π–A2σ) Band System of Aluminium Monoxide |doi=10.1038/202383a0 |journal=Nature |volume=202 |issue=4930 |year=1964 |pages=383–384 |bibcode=1964Natur.202..383T |s2cid=4163250 |postscript=none}}, and in [[dialanes]] (R<sub>2</sub>Al—AlR<sub>2</sub>); see {{cite journal|last1=Uhl|first1=Werner |title=Organoelement Compounds Possessing Al—Al, Ga—Ga, In—In, and Tl—Tl Single Bonds| journal=Advances in Organometallic Chemistry |volume=51 |year=2004 |pages=53–108 |doi=10.1016/S0065-3055(03)51002-4 }}</ref><!--
--><ref name="Zintl">Negative oxidation states of p-block metals (Al, Ga, In, Sn, Tl, Pb, Bi, Po) and metalloids (Si, Ge, As, Sb, Te, At) may occur in [[Zintl phase]]s, see: {{cite book|title=Moderne Anorganische Chemie|date=2007|editor1-first=Erwin|editor1-last=Riedel|page=259|language=de |postscript=none}}, and {{cite web|url=http://ruby.chemie.uni-freiburg.de/Vorlesung/intermetallische_6_2.html|title=Vorlesung Intermetallische Phasen §&nbsp;6.2 Binäre Zintl-Phasen|language=de}}</ref><!--
--><ref>Unstable carbonyl of Al(0) has been detected in reaction of [[Trimethylaluminum|Al<sub>2</sub>(CH<sub>3</sub>)<sub>6</sub>]] with carbon monoxide; see {{cite journal |first1=Ramiro |last1=Sanchez |first2=Caleb |last2=Arrington |first3=C. A. |last3=Arrington Jr. |title=Reaction of trimethylaluminum with carbon monoxide in low-temperature matrixes |journal=American Chemical Society |volume=111 |issue=25 |date=December 1, 1989 |page=9110-9111 |doi=10.1021/ja00207a023 |url=https://www.osti.gov/biblio/6973516-reaction-trimethylaluminum-carbon-monoxide-low-temperature-matrices}}</ref><!--
--><ref>Al(−2) has been observed in Sr<sub>14</sub>[Al<sub>4</sub>]<sub>2</sub>[Ge]<sub>3</sub>, see {{cite journal|last1=Wemdorff|first1=Marco|last2=Röhr|first2=Caroline|title=Sr<sub>14</sub>[Al<sub>4</sub>]<sub>2</sub>[Ge]<sub>3</sub>: Eine Zintl-Phase mit isolierten [Ge]<sup>4–</sup>- und [Al<sub>4</sub>]<sup>8–</sup>-Anionen / Sr<sub>14</sub>[Al<sub>4</sub>]<sub>2</sub>[Ge]<sub>3</sub>: A Zintl Phase with Isolated [Ge]<sup>4–</sup>- and [Al<sub>4</sub>]<sup>8–</sup> Anions|journal=Zeitschrift für Naturforschung B|language=de|volume=62|issue=10|year=2007|page=1227|doi=10.1515/znb-2007-1001|s2cid=94972243}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Si |os= −4b, −3, −2, −1, 0, +1, +2, +3, +4b
|ref=<!--
--><ref name=ZeroValentTin>{{cite web |title=New Type of Zero-Valent Tin Compound |url= https://www.chemistryviews.org/details/news/9745121/New_Type_of_Zero-Valent_Tin_Compound.html |publisher=[[Chemistry Europe]] |date=27 August 2016}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=P  |os= −3b, −2, −1, 0, +1, +2, +3b, +4, +5b
|ref=<!--
--><ref>P(0) has been observed, see {{cite journal|doi=10.1021/ja807828t|title=Carbene-Stabilized Diphosphorus|year=2008|last1=Wang|first1=Yuzhong|last2=Xie|first2=Yaoming|last3=Wei|first3=Pingrong|last4=King|first4=R. Bruce|last5=Schaefer|first5=Iii|last6=Schleyer|first6=Paul v. R.|last7=Robinson|first7=Gregory H.|journal=Journal of the American Chemical Society|volume=130|issue=45|pages=14970–1|pmid=18937460}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=S  |os= −2b, −1, 0, +1, +2b, +3, +4b, +5, +6b
|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Cl |os= −1b, +1b, +2, +3b, +4, +5b, +6, +7b
|ref=<!--
--><ref>The equilibrium Cl<sub>2</sub>O<sub>6</sub>⇌2ClO<sub>3</sub> is mentioned by Greenwood and Earnshaw, but it has been refuted, see {{cite journal|first=Maria|last=Lopez|author2=Juan E. Sicre|title=Physicochemical properties of chlorine oxides. 1. Composition, ultraviolet spectrum, and kinetics of the thermolysis of gaseous dichlorine hexoxide|journal=J. Phys. Chem. |year=1990|volume=94|issue=9|pages=3860–3863|doi=10.1021/j100372a094}}, and Cl<sub>2</sub>O<sub>6</sub> is actually chlorine(V,VII) oxide. However, ClO<sub>3</sub> has been observed, see {{cite journal|first1=Hinrich|last1=Grothe|first2=Helge|last2=Willner|title=Chlorine Trioxide: Spectroscopic Properties, Molecular Structure, and Photochemical Behavior|journal=Angew. Chem. Int. Ed.|year=1994|volume=33|issue=14|pages=1482–1484|doi=10.1002/anie.199414821}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ar |os=0b|ref=<!--
--><ref>Ar(0) has been observed in [[argon fluorohydride]] (HArF) and ArCF<sub>2</sub><sup>2+</sup>, see {{cite journal |display-authors=4 |last1=Lockyear|first1=J.F. |last2=Douglas|first2=K. |last3=Price|first3=S.D. |last4=Karwowska|first4=M. |last5=Fijalkowski|first5=K.J. |last6=Grochala|first6=W. |last7=Remeš|first7=M. |last8=Roithová|first8=J. |last9=Schroder|first9=D. |name-list-style=amp |date=2010 |title=Generation of the ArCF<sub>2</sub><sup>2+</sup> Dication |journal=[[Journal of Physical Chemistry Letters]] |volume=1 |page=358 |doi=10.1021/jz900274p}}</ref> |note= |datacheck=yes }}
<!--- Period 4 --->
{{List of oxidation states of the elements/row |symbol=K  |os= −1, +1b
|ref=<!--
--><ref name="G&E Lithides"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ca |os= +1, +2b
|ref=<!--
--><ref>Ca(I) has been observed; see {{cite journal|last1=Krieck|first1=Sven|last2=Görls|first2=Helmar|last3=Westerhausen|first3=Matthias|title=Mechanistic Elucidation of the Formation of the Inverse Ca(I) Sandwich Complex [(thf)<sub>3</sub>Ca(μ-C<sub>6</sub>H<sub>3</sub>-1,3,5-Ph<sub>3</sub>)Ca(thf)<sub>3</sub>] and Stability of Aryl-Substituted Phenylcalcium Complexes|journal=Journal of the American Chemical Society|volume=132|issue=35|pages=12492–501|year=2010|pmid=20718434|doi=10.1021/ja105534w}}</ref><ref name="Ca0">Octacarbonyl complexes isolated of Ca, Sr, Ba have been observed in a neon matrix, but it remains unclear whether these are metal(0) complexes because calculations disagree whether the metal is covalently or ionically bonded to the ligands; see {{cite journal |first1=X. |last1=Wu |first2=L. |last2=Zhao |first3=J. |last3=Jin |first4=S. |last4=Pan |first5=W. |last5=Li |first6=X. |last6=Jin |first7=G. |last7=Wang |first8=M. |last8=Zhou |first9=G. |last9=Frenking |title=Observation of alkaline earth complexes M(CO)8 (M = Ca, Sr, or Ba) that mimic transition metals |doi=10.1126/science.aau0839 |journal=Science |volume=361 |issue=6405 |year=2018 |pages=912–916 |pmid=30166489 |bibcode=2018Sci...361..912W |s2cid=52131470 |postscript=none}}</ref>
 |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Sc |os= 0, +1, +2, +3b
|ref=<!--
--><ref>Sc(0) has been observed; see {{cite journal |author=F. Geoffrey N. Cloke|author2=Karl Khan|author3=Robin N. Perutz|name-list-style=amp |date=1991|title=η-Arene complexes of scandium(0) and scandium(II) |journal= J. Chem. Soc., Chem. Commun.|issue=19|pages=1372–1373|doi= 10.1039/C39910001372}}</ref><!--
--><ref>Sc(I) has been observed; see {{cite journal|author=Polly L. Arnold|author2=F. Geoffrey|author3=N. Cloke|author4=Peter B. Hitchcock|author5=John F. Nixon|name-list-style=amp|date=1996|title=The First Example of a Formal Scandium(I) Complex: Synthesis and Molecular Structure of a 22-Electron Scandium Triple Decker Incorporating the Novel 1,3,5-Triphosphabenzene Ring |journal=J. Am. Chem. Soc.|volume=118|issue=32|pages=7630–7631|doi= 10.1021/ja961253o}}</ref><!--
--><ref>Sc(II) has been observed; see {{cite journal|last1=Woen|first1=David H.|last2=Chen|first2=Guo P.|last3=Ziller|first3=Joseph W.|last4=Boyle|first4=Timothy J.|last5=Furche|first5=Filipp|last6=Evans|first6=William J.|title=Solution Synthesis, Structure, and CO Reduction Reactivity of a Scandium(II) Complex|journal=Angewandte Chemie International Edition|date=January 2017|doi=10.1002/anie.201611758|pmid=28097771|volume=56|issue=8|pages=2050–2053}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ti |os= −2, −1, 0, +1, +2b, +3b, +4b
|ref=<!--
--><ref>Ti(I) has been observed in [Ti(η<sup>6</sup>-1,3,5-C<sub>6</sub>H<sub>3</sub><sup>''i''</sup>Pr<sub>3</sub>)2][BAr<sub>4</sub>] (Ar = C<sub>6</sub>H<sub>5</sub>, ''p''-C<sub>6</sub>H<sub>4</sub>F, 3,5-C<sub>6</sub>H<sub>3</sub>(CF<sub>3</sub>)<sub>2</sub>); see {{cite journal|title=Synthesis of [Ti(η<sup>6</sup>-1,3,5-C<sub>6</sub>H<sub>3</sub>''i''Pr<sub>3</sub>)<sub>2</sub>][BAr<sub>4</sub>] (Ar = C<sub>6</sub>H<sub>5</sub>, p-C<sub>6</sub>H<sub>4</sub>F, 3,5-C<sub>6</sub>H<sub>3</sub>(CF<sub>3</sub>)<sub>2</sub>), the First Titanium(I) Derivatives |first1=Fausto|last1=Calderazzo |first2=Isabella|last2=Ferri |first3=Guido|last3=Pampaloni |first4=Ulli|last4=Englert |first5=Malcolm L. H.|last5=Green |journal=Organometallics|year=1997|volume=16|issue=14|pages=3100–3101|doi=10.1021/om970155o}}</ref><!--
--><ref name="Carbonyls">Ti(−2), V(−3), Cr(−4), Co(−3), Zr(−2), Nb(−3), Mo(−4), Ru(−2), Rh(−3), Hf(−2), Ta(−3), and W(−4) occur in anionic binary [[metal carbonyls]]; see [http://d-nb.info/956310893/34], p. 4 (in German); [https://books.google.com/books?id=dP4LTfaPzAMC&pg=PA97&dq=%22%5BCr%28CO%294%5D4-%22&hl=en&sa=X&ei=ncroVMihLYO8ygO22YLYAQ&ved=0CBsQ6AEwAA#v=onepage&q&f=false], pp. 97–100<!-- Ti(−4) and Zr, Hf(−6) on p. 100 seem to be wrong: Ti, Zr, Hf are less electronegative than Sn, so cited compounds have Ti(0) and Zr, Hf(+2) -->; [https://books.google.com/books?id=n5r-NFT46TkC&printsec=frontcover&hl=ru#v=onepage&q&f=false], p. 239</ref><!--
--><ref>Ti(−1) has been reported in [Ti([[2,2'-Bipyridine|bipy]])<sub>3</sub>]<sup>−</sup>, but was later shown to be Ti(+3); see {{cite journal|doi=10.1021/ic302799s|pmid=23387926|title=Electronic structures of homoleptic [tris(2,2'-bipyridine)M]n complexes of the early transition metals (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta; n = 1+, 0, 1-, 2-, 3-): an experimental and density functional theoretical study|year=2013|last1=Bowman|first1=A. C.|last2=England|first2=J.|last3=Sprouls|first3=S.|last4=Weihemüller|first4=T.|last5=Wieghardt|first5=K.|journal=Inorganic Chemistry|volume=52|issue=4|pages=2242–56}} However, Ti(−1) occurs in [Ti(η-C<sub>6</sub>H<sub>6</sub>]<sup>−</sup> and [Ti(η-C<sub>6</sub>H<sub>5</sub>CH<sub>3</sub>)]<sup>−</sup>, see {{cite journal|doi=10.1039/C39840000729|title=Synthesis of anionic sandwich compounds: [Ti(η-C<sub>6</sub>H<sub>5</sub>R)<sub>2</sub>]<sup>–</sup> and the crystal structure of [K(18-crown-6)(µ-H)Mo(η-C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>]|year=1984|last1=Bandy|first1=J. A.|last2=Berry|first2=A.|last3=Green|first3=M. L. H.|last4=Perutz|first4=R. N.|last5=Prout|first5=K.|last6=Verpeautz|first6=J.-N.|journal=Inorganic Chemistry|volume=52|issue=4|pages=729–731}}</ref><!--
--><ref>{{cite journal |last1= Jilek |first1= Robert E. |last2= Tripepi |first2= Giovanna |last3= Urnezius |first3= Eugenijus |last4= Brennessel |first4= William W. |last5= Young |first5= Victor G. Jr. |last6= Ellis |first6= John E. |title= Zerovalent titanium–sulfur complexes. Novel dithiocarbamato derivatives of Ti(CO)<sub>6</sub>: [Ti(CO)<sub>4</sub>(S<sub>2</sub>CNR<sub>2</sub>)]<sup>−</sup> |journal= Chem. Commun. |issue= 25 |year= 2007 |pages= 2639–2641 |doi= 10.1039/B700808B |pmid= 17579764}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=V  |os= −3, −1, 0, +1, +2b, +3b, +4b, +5b
|ref=<!--
--><ref name="Carbonyls"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Cr |os= −4, −2, −1, 0, +1, +2b, +3b, +4, +5, +6b
|ref=<!--
--><ref name="Carbonyls"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Mn |os= −3, −2, −1, 0, +1, +2b, +3b, +4b, +5, +6b, +7b|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Fe |os= −4, −2, −1, 0, +1, +2b, +3b, +4, +5, +6, +7
|ref=<!--
--><ref>Fe(VII) has been observed in [FeO<sub>4</sub>]<sup>−</sup>; see {{cite journal|last1=Lu|first1=Jun-Bo|last2=Jian|first2=Jiwen|last3=Huang|first3=Wei|last4=Lin|first4=Hailu|last5=Zhou|first5=Mingfei|title=Experimental and theoretical identification of the Fe(VII) oxidation state in FeO<sub>4</sub><sup>−</sup>|journal=Physical Chemistry Chemical Physics|volume=18|issue=45|year=2016|pages=31125–31131|doi=10.1039/C6CP06753K|pmid=27812577|bibcode=2016PCCP...1831125L}}</ref><!--
--><ref>Fe(VIII) has been reported; see {{cite journal|doi=10.1595/147106704X10801|title=Higher Oxidation States of Iron in Solid State: Synthesis and Their Mössbauer Characterization – Ferrates – ACS Symposium Series (ACS Publications)|year=2008|author1=Yurii D. Perfiliev|author2=Virender K. Sharma|volume=48|issue=4|pages=157–158|journal=Platinum Metals Review}} However, its existence has been disputed.</ref><!--
--><ref name="MetalAnions">Fe(−4), Ru(−4), and Os(−4) have been observed in metal-rich compounds containing octahedral complexes [MIn<sub>6−''x''</sub>Sn<sub>''x''</sub>]; Pt(−3) (as a dimeric anion [Pt–Pt]<sup>6−</sup>), Cu(−2), Zn(−2), Ag(−2), Cd(−2), Au(−2), and Hg(−2) have been observed (as dimeric and monomeric anions; dimeric ions were initially reported to be [T–T]<sup>2−</sup> for Zn, Cd, Hg, but later shown to be [T–T]<sup>4−</sup> for all these elements) in La<sub>2</sub>Pt<sub>2</sub>In, La<sub>2</sub>Cu<sub>2</sub>In, Ca<sub>5</sub>Au<sub>3</sub>, Ca<sub>5</sub>Ag<sub>3</sub>, Ca<sub>5</sub>Hg<sub>3</sub>, Sr<sub>5</sub>Cd<sub>3</sub>, Ca<sub>5</sub>Zn<sub>3</sub>(structure (AE<sup>2+</sup>)<sub>5</sub>(T–T)<sup>4−</sup>T<sup>2−</sup>⋅4e<sup>−</sup>), Yb<sub>3</sub>Ag<sub>2</sub>, Ca<sub>5</sub>Au<sub>4</sub>, and Ca<sub>3</sub>Hg<sub>2</sub>; Au(–3) has been observed in ScAuSn and in other 18-electron half-Heusler compounds. See {{cite journal|title=Late transition metal anions acting as p-metal elements|year=2008|author1=Changhoon Lee|author2=Myung-Hwan Whangbo|volume=10|issue=4|pages=444–449|journal=Solid State Sciences|doi=10.1016/j.solidstatesciences.2007.12.001|bibcode=2008SSSci..10..444K}} and {{cite journal|doi=10.1002/zaac.200900421|title=Analysis of Electronic Structures and Chemical Bonding of Metal-rich Compounds. 2. Presence of Dimer (T–T)<sup>4–</sup> and Isolated T<sup>2–</sup> Anions in the Polar Intermetallic Cr<sub>5</sub>B<sub>3</sub>-Type Compounds AE<sub>5</sub>T<sub>3</sub> (AE = Ca, Sr; T = Au, Ag, Hg, Cd, Zn)|year=2010|author1=Changhoon Lee|author2=Myung-Hwan Whangbo|author3=Jürgen Köhler|volume=636|issue=1|pages=36–40|journal=Zeitschrift für Anorganische und Allgemeine Chemie}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Co |os= −3, −1, 0, +1, +2b, +3b, +4, +5
|ref=<!--
--><ref name="Carbonyls"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ni |os= −2, −1, 0, +1, +2b, +3, +4
|ref=<!--
--><ref>Ni(−2) has been observed in Li<sub>2</sub>[Ni([[1,5-cyclooctadiene|1,5-COD]])<sub>2</sub>], see {{cite journal|first1=Klaus|last1=Jonas|title=Dilithium-Nickel-Olefin Complexes. Novel Bimetal Complexes Containing a Transition Metal and a Main Group Metal|journal=Angew. Chem. Int. Ed.|year=1975|volume=14|issue=11|pages=752–753|doi=10.1002/anie.197507521}} and {{cite journal|doi=10.1021/ic052110i|pmid=16602773|title=Adventures with Substances Containing Metals in Negative Oxidation States|year=2006|last1=Ellis|first1=John E.|journal=Inorganic Chemistry|volume=45|issue=8|pages=3167–86}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Cu |os= −2, 0, +1b, +2b, +3, +4
|ref=<!--
--><ref name="MetalAnions"/><!--
--><ref>Cu(0) has been observed in Cu(tris[2-(diisopropylphosphino)-
phenyl]borane), see {{cite journal|first1=Marc-Etienne|last1=Moret|first2=Limei|last2=Zhang|first3=Jonas C.|last3=Peters|title=A Polar Copper–Boron One-Electron σ-Bond|journal=J. Am. Chem. Soc|year=2013|volume=135|issue=10|pages=3792–3795|doi=10.1021/ja4006578|pmid=23418750|url=https://authors.library.caltech.edu/37931/}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Zn |os= −2, 0, +1, +2b
|ref=<!--
--><ref name="MetalAnions"/><!--
--><ref>Zn(0) has been observed; see {{cite journal|doi=10.1021/ja402351x|title=A Singlet Biradicaloid Zinc Compound and Its Nonradical Counterpart|year=2013|last1=Singh|first1=Amit Pratap|last2=Samuel|first2=Prinson P.|last3=Roesky|first3=Herbert W.|last4=Schwarzer|first4=Martin C.|last5=Frenking|first5=Gernot|last6=Sidhu|first6=Navdeep S.|last7=Dittrich|first7=Birger|journal=J. Am. Chem. Soc.|volume=135|issue=19|pages=7324–9|pmid=23600486}} and {{cite journal|doi=10.1021/ar5003494|title=Cyclic (Alkyl)(Amino)Carbenes (CAACs): Stable Carbenes on the Rise|year=2015|last1=Soleilhavoup|first1=Michèle|last2=Bertrand|first2=Guy|journal=Acc. Chem. Res.|volume=48|issue=2|pages=256–266|pmid=25515548}}</ref><!--
--><ref>Zn(I) has been observed in [[decamethyldizincocene]] (Zn<sub>2</sub>(η<sup>5</sup>–C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>); see {{cite journal |author1=Resa, I. |author2=Carmona, E. |author3=Gutierrez-Puebla, E. |author4=Monge, A. |title= Decamethyldizincocene, a Stable Compound of Zn(I) with a Zn-Zn Bond |journal= [[Science (journal)|Science]] |doi= 10.1126/science.1101356 |pmid= 15326350 |year= 2004 |volume= 305 |issue= 5687 |pages= 1136–8|bibcode=2004Sci...305.1136R|s2cid=38990338 }}</ref><!--
--><ref>Zn(III) has been predicted to be stable in compounds with highly stabilized borane-based trianions, but no Zn(III) candidates are known experimentally; see {{cite journal |author1=Hong Fang |author2=Huta Banjade |author3=Deepika |author4=Puru Jena |title=Realization of the Zn3+ oxidation state |journal=Nanoscale |date=2021 |volume=13 |issue=33 |pages=14041–14048 |doi=10.1039/D1NR02816B |pmid=34477685 |s2cid=237400349 |language=English}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ga |os= −5, −4, −3, −2, −1, 0, +1, +2, +3b
|ref=<!--
--><ref name="Zintl"/><!--
--><ref>Ga(−2), Ga(−4), and Ga(−5) have been observed in the magnesium gallides MgGa, Mg<sub>2</sub>Ga, and Mg<sub>5</sub>Ga<sub>2</sub>, respectively; see {{cite news|url=http://www.uni-kassel.de/upress/online/frei/978-3-7281-2597-2.volltext.frei.pdf|author=Patrick Hofmann|title=Colture. Ein Programm zur interaktiven Visualisierung von Festkörperstrukturen sowie Synthese, Struktur und Eigenschaften von binären und ternären Alkali- und Erdalkalimetallgalliden|page=72|language=de}}</ref><!--
--><ref>Ga(−3) has been observed in LaGa, see {{cite journal|lang=de|first1=Ines|last1=Dürr|first2=Britta|last2=Bauer|first3=Caroline|last3=Röhr|title=Lanthan-Triel/Tetrel-ide La(Al,Ga)<sub>''x''</sub>(Si,Ge)<sub>1-''x''</sub>. Experimentelle und theoretische Studien zur Stabilität intermetallischer 1:1-Phasen|journal=Z. Naturforsch.|year=2011|volume=66b|pages=1107–1121|url=http://www.znaturforsch.com/s66b/s66b1107.pdf}}</ref><!--
--><ref>Ga(0) has been observed in [[Gallium monoiodide]] among other gallium's oxidation states</ref>
|note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ge |os= −4b, −3, −2, −1, 0, +1, +2b, +3, +4b
|ref=<!--
--><ref>Ge(−1), Ge(−2), and Ge(−3) have been observed in [[germanide]]s; see {{cite book|publisher=Walter de Gruyter|year=1995|edition=101| pages=953–959|isbn=978-3-11-012641-9|title=Lehrbuch der Anorganischen Chemie|first=Arnold F.|last=Holleman |author2=Wiberg, Egon |author3=Wiberg, Nils|language=de|chapter=Germanium}}</ref><!--
--><ref name=ZeroValentTin/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=As |os= −3b, −2, −1, 0, +1, +2, +3b, +4, +5b
|ref=<!--
--><ref name="Zintl"/><!--
--><ref>As(0) has been observed; see {{cite journal|doi=10.1002/chem.200902840|title=Carbene Stabilization of Diarsenic: From Hypervalency to Allotropy|year=2010|last1=Abraham|first1=Mariham Y.|last2=Wang|first2=Yuzhong|last3=Xie|first3=Yaoming|last4=Wei|first4=Pingrong|last5=Shaefer III|first5=Henry F.|last6=Schleyer|first6=P. von R.|last7=Robinson|first7=Gregory H.|journal=Chemistry: A European Journal|volume=16|issue=2|pages=432–5|pmid=19937872}}</ref><!--
--><ref>As(I) has been observed in [[arsenic(I) iodide]] (AsI); see {{cite journal|doi=10.1021/ic049281s|pmid=15360247|title=Stabilized Arsenic(I) Iodide: A Ready Source of Arsenic Iodide Fragments and a Useful Reagent for the Generation of Clusters|year=2004|last1=Ellis|first1=Bobby D.|last2=MacDonald|first2=Charles L. B.|journal=Inorganic Chemistry|volume=43|issue=19|pages=5981–6}}</ref><!--
--><ref>As(IV) has been observed in [[arsenic(IV) hydroxide]] (As(OH)<sub>4</sub>) and {{chem|HAsO-}}; see {{cite journal|doi=10.1021/ic00313a007|title=Arsenic(IV). A pulse-radiolysis study|year=1989|last1=Kläning|first1=Ulrik K.|last2=Bielski|first2=Benon H. J.|last3=Sehested|first3=K.|journal=Inorganic Chemistry|volume=28|issue=14|pages=2717–24}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Se |os= −2b, −1, 0, +1, +2b, +3, +4b, +5, +6b
|ref=<!--
--><ref>Se(−1) has been observed in [[selenide|diselenide]]s(2−) (Se<sub>2</sub><sup>2−</sup>).</ref><!--
--><ref>A Se(0) atom has been identified using DFT in [ReOSe(2-pySe)<sub>3</sub>]; see {{cite journal|doi=10.1016/j.inoche.2014.04.003|title=Synthesis and structure of [ReOSe(2-Se-py)3]: A rhenium(V) complex with selenium(0) as a ligand|year=2014|last1=Cargnelutti|first1=Roberta|last2=Lang|first2=Ernesto S.|last3=Piquini|first3=Paulo|last4=Abram|first4=Ulrich|journal=Inorganic Chemistry Communications|volume=45|pages=48–50|issn=1387-7003}}</ref><!--
--><ref>Se(I) has been observed in [[selenium(I) chloride]] (Se<sub>2</sub>Cl<sub>2</sub>); see {{cite web|url=http://www.webelements.com/webelements/compounds/text/Se/Cl2Se2-10025680.html|title=Selenium: Selenium(I) chloride compound data|access-date=2007-12-10|publisher=WebElements.com}}</ref><!--
--><ref>Se(III) has been observed in Se<sub>2</sub>NBr<sub>3</sub>; see {{cite journal|title=Se<sub>2</sub>NBr<sub>3</sub>, Se<sub>2</sub>NCl<sub>5</sub>, Se<sub>2</sub>NCl<sup>−</sup><sub>6</sub>: New Nitride Halides of Selenium(III) and Selenium(IV)| volume= 2|issue= 11|pages=1393–1396|year=1996|doi=10.1002/chem.19960021108|last1=Lau|first1=Carsten|last2=Neumüller|first2=Bernhard|last3=Vyboishchikov|first3=Sergei F.|last4=Frenking|first4=Gernot|last5=Dehnicke|first5=Kurt|last6=Hiller|first6=Wolfgang|last7=Herker|first7=Martin|journal=Chemistry: A European Journal}}</ref><!--
--><ref>Se(V) has been observed in {{chem|SeO<sub>3</sub><sup>−</sup>}} and {{chem|HSeO<sub>4</sub><sup>2-</sup>}}; see {{cite journal|doi=10.1021/j100412a112|title=Selenium(V). A pulse radiolysis study|year=1986|last1=Kläning|first1=Ulrik K.|last2=Sehested|first2=K.|journal=Inorganic Chemistry|volume=90|issue=21|pages=5460–4|url=http://orbit.dtu.dk/en/publications/seleniumv-a-pulse-radiolysis-study(01d1260d-45a3-4a09-8316-e6f6b4993561).html}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Br |os= −1b, +1b, +2, +3b, +4, +5b, +7|ref=<!--
--><ref>Br(II) is known to occur in bromine monoxide [[Radical (chemistry)|radical]]; see [https://pubs.acs.org/doi/10.1021/j100382a032]</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Kr |os= 0b, +1, +2|ref= |note= |datacheck=yes }}
<!--- Period 5 --->
{{List of oxidation states of the elements/row |symbol=Rb |os= −1, +1b
|ref=<!--
--><ref name="G&E Lithides"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Sr |os= +1, +2b
|ref=<!--
--><ref>Sr(I) has been observed in [[strontium monofluoride]] (SrF); see {{cite journal|url=http://bernath.uwaterloo.ca/media/149.pdf |title=High-Resolution Infrared Emission Spectrum of Strontium Monofluoride |journal=Journal of Molecular Spectroscopy |volume=175 |issue=1 |pages=158–171 |year=1996 |author=P. Colarusso |bibcode=1996JMoSp.175..158C |doi=10.1006/jmsp.1996.0019 |last2=Guo |first2=B. |last3=Zhang |first3=K.-Q. |last4=Bernath |first4=P.F. |display-authors=etal |url-status=dead |archive-url=https://web.archive.org/web/20120308063843/http://bernath.uwaterloo.ca/media/149.pdf |archive-date=2012-03-08 }}</ref><ref name="Ca0"/>
 |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Y  |os= 0, +1, +2, +3b
|ref=<!--
--><ref name="Cloke1993"/><!--
--><ref>Y(I) has been observed in [[yttrium(I) bromide]] (YBr); see {{cite web|url=http://www.openmopac.net/data_normal/yttrium(i)%20bromide_jmol.html |title=Yttrium: yttrium(I) bromide compound data |access-date=2007-12-10 |publisher=OpenMOPAC.net |url-status=dead |archive-url=https://web.archive.org/web/20110723233118/http://www.openmopac.net/data_normal/yttrium%28i%29%20bromide_jmol.html |archive-date=2011-07-23 }}</ref><!--
--><ref>Y(II) has been observed in <!-- [[yttrium(II) hydride]] (YH<sub>2</sub>); see {{cite web|url=http://www.webelements.com/webelements/compounds/text/Y/H2Y1-13598351.html|title=Yttrium: yttrium(II) hydride compound data|access-date=2007-12-10|publisher=WebElements.com}} Isn't YH<sub>2</sub> electride-like?-->[(18-crown-6)K][(C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub>)<sub>3</sub>Y]; see {{cite journal|last1=MacDonald|first1=M. R.|last2=Ziller|first2=J. W.|last3=Evans|first3=W. J.|year=2011|title=Synthesis of a Crystalline Molecular Complex of Y<sup>2+</sup>, [(18-crown-6)K][(C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub>)<sub>3</sub>Y]|journal=J. Am. Chem. Soc.|volume=133|issue=40|pages=15914–17|doi=10.1021/ja207151y|pmid=21919538}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Zr |os= −2, 0, +1, +2, +3, +4b
|ref=<!----><ref name="Carbonyls"/><!--
--><ref>Zr(−1) has been reported in [Zr([[2,2'-Bipyridine|bipy]])<sub>3</sub>]<sup>−</sup> (see {{Greenwood&Earnshaw|page=960}} and {{cite book|publisher=Walter de Gruyter|year=1995|edition=101|pages=1413|isbn=978-3-11-012641-9|title=Lehrbuch der Anorganischen Chemie|first=Arnold F.|last=Holleman |author2=Wiberg, Egon |author3=Wiberg, Nils|language=de|chapter=Zirconium}}), but was later shown to be Zr(+4); see {{cite journal|doi=10.1021/ic302799s|pmid=23387926|title=Electronic structures of homoleptic [tris(2,2'-bipyridine)M]n complexes of the early transition metals (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta; n = 1+, 0, 1-, 2-, 3-): an experimental and density functional theoretical study|year=2013|last1=Bowman|first1=A. C.|last2=England|first2=J.|last3=Sprouls|first3=S.|last4=Weihemüller|first4=T.|last5=Wieghardt|first5=K.|journal=Inorganic Chemistry|volume=52|issue=4|pages=2242–56}}</ref><!--
--><ref name="Zr0">Zr(0) and Hf(0) occur in (η<sup>6</sup>-(1,3,5-<sup>''t''</sup>Bu)<sub>3</sub>C<sub>6</sub>H<sub>3</sub>)<sub>2</sub>M (M=Zr, Hf) and [(η<sup>5</sup>-C<sub>5</sub>R<sub>5</sub>M(CO)<sub>4</sub>]<sup>−</sup>, see {{cite book|publisher=Elsevier Ltd.|year=2007|volume=4|pages=697–739|doi=10.1016/B0-08-045047-4/00062-5|title=Comprehensive Organometallic Chemistry III. From Fundamentals to Applications|first=P. J.|last=Chirik |author2=Bradley, C. A. |chapter=4.06 - Complexes of Zirconium and Hafnium in Oxidation States 0 to ii|isbn=9780080450476}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Nb |os= −3, −1, 0, +1, +2, +3, +4, +5b
|ref=<!--
--><ref name="Carbonyls"/><!--
--><ref name="NbTa0">Complexes of Nb(0) and Ta(0) have been observed, see {{cite book|publisher=Newnes|year=2003|edition=2|volume=4|pages=297–299|editor1=J. A. McCleverty|editor2=T.J. Meyer|isbn=978-0-08-091316-2|title=Comprehensive Coordination Chemistry II: From Biology to Nanotechnology|first=Arnold F.|last=Holleman |author2=Wiberg, Egon |author3=Wiberg, Nils|chapter=4.5.7. Niobium(0) and Tantalum(0)}}</ref><!--
--><ref name="NbTa">Nb(I) and Ta(I) occur in [[cyclopentadienyl|Cp]]Nb(CO)<sub>4</sub> and [[cyclopentadienyl|Cp]]Ta(CO)<sub>4</sub>, see {{cite book|publisher=Walter de Gruyter|year=1995|edition=101| pages=1430|isbn=978-3-11-012641-9|title=Lehrbuch der Anorganischen Chemie|first=Arnold F.|last=Holleman |author2=Wiberg, Egon |author3=Wiberg, Nils|language=de|chapter=Tantal}} and {{cite book|publisher=Academic Press|year=1969|pages=11|isbn=978-0-32-315996-8|title=Transition-Metal Organometallic Chemistry: An Introduction|first=R. Bruce|last=King}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Mo |os= −4, −2, −1, 0, +1, +2, +3, +4b, +5, +6b
|ref=<!--
--><ref name="Carbonyls"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Tc |os= −3, −1, 0, +1, +2, +3, +4b, +5, +6, +7b|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ru |os= −4, −2, 0, +1, +2, +3b, +4b, +5, +6, +7, +8
|ref=<!--
--><ref name="Carbonyls"/><!--
--><ref name="MetalAnions"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Rh |os= −3, −1, 0, +1, +2, +3b, +4, +5, +6, +7
|ref=<!--
--><ref name="Carbonyls"/><!--
--><ref>{{cite journal |journal= Chemical Physics Letters |volume= 108 |issue= 6 |year= 1984 |pages= 627–630 |title= Electron paramagnetic resonance spectroscopic studies on the zero-valent rhodium complex [Rh(P(OPr<sup>''i''</sup>)<sub>3</sub>)<sub>4</sub>] at X-and Q-band frequencies |first1= G.N. |last1= George |first2= S.I. |last2= Klein |first3= J.F. |last3= Nixon |doi= 10.1016/0009-2614(84)85069-1|bibcode= 1984CPL...108..627G }}</ref><ref>Rh(VII) is known in the RhO<sub>3</sub><sup>+</sup> cation, see {{cite journal |title=The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3]+ |journal=Angew. Chem. Int. Ed. |date=2022 |doi=10.1002/anie.202207688}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Pd |os= 0b, +1, +2b, +3, +4b, +5
|ref=<!--
--><ref>Pd(I) has been observed; see {{cite journal|last1= Crabtree|first1= R. H.|title= CHEMISTRY: A New Oxidation State for Pd?|journal= [[Science (journal)|Science]]|volume= 295|pages= 288–289|year= 2002|doi= 10.1126/science.1067921|pmid= 11786632|issue= 5553|s2cid= 94579227}}</ref><!--
--><ref>Pd(III) has been observed; see {{cite book|last1=Powers |first1=D. C. |last2=Ritter |first2=T. |title=Palladium(III) in Synthesis and Catalysis |journal=Top. Organomet. Chem. |volume=35 |pages=129–156 |date=2011 |doi=10.1007/978-3-642-17429-2_6 |pmid=21461129 |url=http://www.chem.harvard.edu/groups/ritter/pdf/2011-129t.pdf |series=Topics in Organometallic Chemistry |isbn=978-3-642-17428-5 |url-status=dead |archive-url=https://web.archive.org/web/20130612065217/http://www.chem.harvard.edu/groups/ritter/pdf/2011-129t.pdf |archive-date=June 12, 2013 |pmc=3066514|bibcode=2011hoso.book..129P }}</ref><ref>Palladium(V) has been identified in complexes with organosilicon compounds containing pentacoordinate palladium; see {{cite journal |first1=Shigeru |last1=Shimada |first2=Yong-Hua |last2=Li |first3=Yoong-Kee |last3=Choe |first4=Masato |last4=Tanaka |first5=Ming |last5=Bao |first6=Tadafumi |last6=Uchimaru |title=Multinuclear palladium compounds containing palladium centers ligated by five silicon atoms |doi=10.1073/pnas.0700450104 |journal=Proceedings of the National Academy of Sciences |volume=104 |year=2007 |issue=19 |pages=7758–7763}}</ref><ref>Palladium(VI) has been claimed to exist in {{cite journal |title=NEW PALLADIUM OXIDATION STATE? |journal=Chem. Eng. News |date=2002 |volume=80 |issue=2 |page=8 |doi=10.1021/cen-v080n002.p008}}, but this has been refuted showing it is a Palladium(II).</ref>|note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ag |os= −2, −1, 0, +1b, +2, +3
|ref=<!--
--><ref name="MetalAnions"/><!--
--><ref>The Ag<sup>−</sup> ion has been observed in metal ammonia solutions: see {{cite journal|doi=10.1021/ic000333x|title=Metal Ammonia Solutions: Solutions Containing Argentide Ions|year=2001|last1=Tran|first1=N. E.|last2=Lagowski|first2=J. J.|journal=Inorganic Chemistry|volume=40|issue=5|pages=1067–68}}</ref><!--
--><ref>Ag(0) has been observed in carbonyl complexes in low-temperature matrices: see {{cite journal|doi=10.1021/ja00427a018|title=Synthesis using metal vapors. Silver carbonyls. Matrix infrared, ultraviolet-visible, and electron spin resonance spectra, structures, and bonding of silver tricarbonyl, silver dicarbonyl, silver monocarbonyl, and disilver hexacarbonyl|year=1976|last1=McIntosh|first1=D.|last2=Ozin|first2=G. A.|journal=J. Am. Chem. Soc.|volume=98|issue=11|pages=3167-75}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Cd |os= −2, +1, +2b
|ref=<!--
--><ref name="MetalAnions"/><!--
--><ref>Cd(I) has been observed in [[cadmium(I) tetrachloroaluminate]] (Cd<sub>2</sub>(AlCl<sub>4</sub>)<sub>2</sub>); see {{cite book|publisher= Walter de Gruyter|year= 1985|edition= 91–100|pages= 1056–1057|isbn= 978-3-11-007511-3|title= Lehrbuch der Anorganischen Chemie|last1= Holleman|first1= Arnold F.|last2= Wiberg|first2=Egon |last3=Wiberg |first3=Nils |language= de|chapter= Cadmium}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=In |os= −5, −2, −1, 0, +1, +2, +3b
|ref=<!--
--><ref name="Zintl"/><!--
--><ref>In(–5) has been observed in La<sub>3</sub>InGe, see {{cite journal|doi=10.1021/ic951378e|title=Synthesis, Structure, and Bonding of Two Lanthanum Indium Germanides with Novel Structures and Properties|year=1996|last1=Guloy|first1=A. M.|last2=Corbett|first2=J. D.|journal=Inorganic Chemistry|volume=35|issue=9|pages=2616–22|pmid=11666477}}</ref><!--
--><ref>In(−2) has been observed in Na<sub>2</sub>In, see [https://books.google.com/books?id=v-04Kn758yIC&pg=PA69&lpg=PA69&dq=zintl+anions+Na2In&source=bl&ots=aXLYIpkfYq&sig=Mqh8WdnvGOt2J2OPVLNqn79YVyk&hl=ru&sa=X&ei=XNDkVNeSJeXOyQOb8oBA&ved=0CBsQ6AEwADgK#v=onepage&q&f=false], p. 69.</ref><!--
--><ref>Unstable In(0) carbonyls and clusters have been detected, see [https://www.researchgate.net/profile/Anthony-Downs-2/publication/6589844_Development_of_the_Chemistry_of_Indium_in_Formal_Oxidation_States_Lower_than_3/links/5a82db2a0f7e9bda869fb52c/Development-of-the-Chemistry-of-Indium-in-Formal-Oxidation-States-Lower-than-3.pdf?origin=publication_detail], p. 6.</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Sn |os= −4b, −3, −2, −1, 0, +1, +2b, +3, +4b
|ref=<!--
--><ref name="Zintl"/><!--
--><ref>Sn(−3) has been observed in [Sn<sub>2</sub>]<sup>6−</sup>, e.g. in (Ba<sub>2</sub>)<sup>4+</sup>(Mg<sub>4</sub>)<sup>8+</sup>Sn<sup>4−</sup>(Sn<sub>2</sub>)<sup>6−</sup>Sn<sup>2−</sup> (with square (Sn<sup>2−</sup>)<sub>n</sub> sheets), see {{cite journal |last1=Papoian |first1=Garegin A. |last2=Hoffmann |first2=Roald |year=2000 |title=Hypervalent Bonding in One, Two, and Three Dimensions: Extending the Zintl–Klemm Concept to Nonclassical Electron-Rich Networks |journal=Angew. Chem. Int. Ed. |volume=2000 |issue= 39|pages=2408–2448 |url=https://www.researchgate.net/publication/12379848 |access-date=2015-02-23 |doi=10.1002/1521-3773(20000717)39:14<2408::aid-anie2408>3.0.co;2-u}}</ref><!--
--><ref>Sn(I) and Sn(III) have been observed in [[organotin compounds]]</ref><!--
--><ref name=ZeroValentTin/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Sb |os= −3b, −2, −1, 0, +1, +2, +3b, +4, +5b
|ref=<!--
--><ref name="Zintl"/><!--
--><ref>Sb(−2) has been observed in [Sb<sub>2</sub>]<sup>4−</sup>, e.g. in RbBa<sub>4</sub>[Sb<sub>2</sub>][Sb][O], see {{cite journal |last1=Boss |first1=Michael |last2=Petri |first2=Denis |last3=Pickhard |first3=Frank |last4=Zönnchen |first4=Peter |last5=Röhr |first5=Caroline |year=2005 |title=Neue Barium-Antimonid-Oxide mit den Zintl-Ionen [Sb]<sup>3−</sup>, [Sb<sub>2</sub>]<sup>4−</sup> und <sup>1</sup><sub>∞</sub>[Sb<sub>n</sub>]<sup>n−</sup> / New Barium Antimonide Oxides containing Zintl Ions [Sb]<sup>3−</sup>, [Sb<sub>2</sub>]<sup>4−</sup> and <sup>1</sup><sub>∞</sub>[Sb<sub>n</sub>]<sup>n−</sup> |journal=Zeitschrift für Anorganische und Allgemeine Chemie |volume=631 |issue= 6–7|pages=1181–1190 |language=de |doi= 10.1002/zaac.200400546}}</ref><!--
--><ref>Sb(0) has been observed, see {{cite news|url=https://pdfs.semanticscholar.org/8817/39f9dfc007d7f77dd7baa63fe12e6079f8ef.pdf|author=Anastas Sidiropoulos|title=Studies of N-heterocyclic Carbene (NHC) Complexes of the Main Group Elements|page=39|doi=10.4225/03/5B0F4BDF98F60|s2cid=132399530}}
</ref><!--
--><ref>Sb(I) and Sb(II) have been observed in [[organoantimony compounds]]; for Sb(I), see {{cite journal |last1=Šimon |first1=Petr |last2=de Proft |first2=Frank |last3=Jambor |first3=Roman |last4=Růžička |first4=Aleš |last5=Dostál |first5=Libor |year=2010 |title=Monomeric Organoantimony(I) and Organobismuth(I) Compounds Stabilized by an NCN Chelating Ligand: Syntheses and Structures |journal=Angewandte Chemie International Edition |volume=49 |issue=32 |pages=5468–5471 |doi= 10.1002/anie.201002209|pmid=20602393}}</ref><!--
--><ref>Sb(IV) has been observed in {{chem|[SbCl<sub>6</sub>]|2-}}, see {{cite journal|doi=10.1246/bcsj.73.1599|title=Production of Sb(IV) Chloro Complex by Flash Photolysis of the Corresponding Sb(III) and Sb(V) Complexes in CH3CN and CHCl3|year=2000|author1=Nobuyoshi Shinohara|author2=Masaaki Ohsima|journal=Bulletin of the Chemical Society of Japan|volume=73|issue=7|pages=1599–1604}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Te |os= −2b, −1, 0, +1, +2b, +3, +4b, +5, +6b
|ref=<!--
--><ref name="Zintl"/><!--
--><ref>Te(0) has been observed in tellurolates.</ref><!--
--><ref>Te(I) has been observed in [[tellurium iodide]] (TeI), see {{cite web|url=http://www.webelements.com/compounds/tellurium/tellurium_iodide.html|title=Tellurium: tellurium iodide|access-date=2015-02-23|publisher=WebElements.com}}</ref><!--
--><ref>Te(III) has been observed in [Te(N(Si[[methyl|Me]]<sub>3</sub>)<sub>2</sub>)<sub>2</sub>]<sup>+</sup>, see {{cite journal |last1=Heinze |first1=Thorsten |last2=Roesky |first2=Herbert W. |last3=Pauer |first3=Frank |last4=Stalke |first4=Dietmar |last5=Sheldrick |first5=George M. |year=1991 |title=Synthesis and Structure of the First Tellurium(III) Radical Cation |journal=Angewandte Chemie International Edition |volume=30 |issue=12 |pages=1678 |doi= 10.1002/anie.199116771 |url=https://www.researchgate.net/publication/237225046 |access-date=2015-02-23}}</ref><!--
--><ref>Te(V) is mentioned by Greenwood and Earnshaw, but they do not give any example of a Te(V) compound. What was long thought to be [[ditellurium decafluoride]] (Te<sub>2</sub>F<sub>10</sub>) is actually bis(pentafluorotelluryl) oxide, F<sub>5</sub>TeOTeF<sub>5</sub>: see {{cite journal |author= Watkins, P. M. |title= Ditellurium decafluoride - A Continuing Myth |journal= Journal of Chemical Education |year= 1974 |volume= 51 |issue= 9 |pages= 520–521 |doi= 10.1021/ed051p520|bibcode= 1974JChEd..51..520W }} However, Te(V) has been observed in {{chem|HTeO-}}, {{chem|TeO-}}, {{chem|HTeO2-}}, and {{chem|TeO3-}}; see {{cite journal|doi=10.1021/jp010577i|title=Tellurium(V). A Pulse Radiolysis Study|year=2001|last1=Kläning|first1=Ulrik K.|last2=Sehested|first2=K.|journal=The Journal of Physical Chemistry A|volume=105|issue=27|pages=6637–45|bibcode=2001JPCA..105.6637K|url=http://orbit.dtu.dk/en/publications/tellurium-5-a-pulse-radiolysis-study(58c2417f-34c0-436d-8a46-211f3d752423).html}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=I  |os= −1b, +1b, +2, +3b, +4, +5b, +6, +7b
|ref=<!--
--><ref>I(II) is known to exist in monoxide (IO); see {{cite journal|last1=Nikitin|first1=I V|title=Halogen monoxides|journal=Russian Chemical Reviews|date=31 August 2008|volume=77|issue=8|pages=739–749|doi=10.1070/RC2008v077n08ABEH003788|bibcode=2008RuCRv..77..739N}}</ref><!--
--><ref>I(IV) has been observed in [[Iodine oxide|iodine dioxide]] (IO<sub>2</sub>); see {{cite book|publisher= Dover Publications, Inc.|year= 1988|edition= 3rd|page= 259|isbn= 978-0-486-65622-9|title= General Chemistry|first= Linus|last= Pauling|chapter= Oxygen Compounds of Nonmetallic Elements}}</ref><!--
--><ref>I(VI) has been observed in IO<sub>3</sub>, IO<sub>4</sub><sup>2−</sup>, H<sub>5</sub>IO<sub>6</sub><sup>−</sup>, H<sub>2</sub>IO<sub>5</sub><sup>2−</sup>, H<sub>4</sub>IO<sub>6</sub><sup>2−</sup>, and HIO<sub>5</sub><sup>3−</sup>; see {{cite journal|doi=10.1039/F19817701707|title=Laser flash photolysis and pulse radiolysis of iodate and periodate in aqueous solution. Properties of iodine(VI)|year=1981|last1=Kläning|first1=Ulrik K.|last2=Sehested|first2=Knud|last3=Wolff|first3=Thomas|journal=J. Chem. Soc., Faraday Trans. 1|volume=77|issue=7|pages=1707–18}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Xe |os= 0b, +2, +4, +6, +8
|ref=<!--
--><ref>Xe compounds: see [[Xenon#Compounds|Xenon]]</ref><!--
--><ref>Xe(0) has been observed in [[tetraxenonogold(II)]] (AuXe<sub>4</sub><sup>2+</sup>).</ref><!--
--><ref>Xe(I) has been reported in [[xenon hexafluoroplatinate]] and [[xenon hexafluororhodate]] (see {{cite book|publisher= Dover Publications, Inc.|year= 1988|edition= 3rd|page= 250|isbn= 978-0-486-65622-9|title= General Chemistry|first= Linus|last= Pauling}}), however these compounds were later found to contain Xe(II).</ref> |note= |datacheck=yes }}
<!--- Period 6 --->
{{List of oxidation states of the elements/row |symbol=Cs |os= −1, +1b
|ref=<!--
--><ref name="G&E Lithides"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ba |os= +1, +2b
|ref=<!--
--><ref>Ba(I) has been observed in [[barium monofluoride]] (BaF); see {{cite journal|url=http://bernath.uwaterloo.ca/media/126.pdf |title=High-Resolution Fourier Transform Infrared Emission Spectrum of Barium Monofluoride |journal=Journal of Molecular Spectroscopy |volume=170 |page=59 |year=1995 |author=P. Colarusso |bibcode=1996JMoSp.175..158C |doi=10.1006/jmsp.1996.0019 |last2=Guo |first2=B. |last3=Zhang |first3=K.-Q. |last4=Bernath |first4=P.F. |issue=1 |display-authors=etal |url-status=dead |archive-url=https://web.archive.org/web/20050310180822/http://bernath.uwaterloo.ca/media/126.pdf |archive-date=2005-03-10 }}</ref><ref name="Ca0"/>
 |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=La |os= 0, +1, +2, +3b
|ref=<!--
--><ref name="Cloke1993">Yttrium and all lanthanides except Ce and Pm have been observed in the oxidation state 0 in bis(1,3,5-tri-t-butylbenzene) complexes, see {{cite journal |journal=Chem. Soc. Rev. |date=1993 |volume=22 |pages=17–24 |first=F. Geoffrey N. |last=Cloke |title=Zero Oxidation State Compounds of Scandium, Yttrium, and the Lanthanides |doi=10.1039/CS9932200017}} and {{cite journal|last1=Arnold|first1=Polly L.|last2=Petrukhina|first2=Marina A.|last3=Bochenkov|first3=Vladimir E.|last4=Shabatina|first4=Tatyana I.|last5=Zagorskii|first5=Vyacheslav V.|last6=Cloke|first9=F. Geoffrey N.|date=2003-12-15|title=Arene complexation of Sm, Eu, Tm and Yb atoms: a variable temperature spectroscopic investigation|journal=Journal of Organometallic Chemistry|volume=688|issue=1–2|pages=49–55|doi=10.1016/j.jorganchem.2003.08.028}}</ref><!--
--><ref name=LnI>La(I), Pr(I), Tb(I), Tm(I), and Yb(I) have been observed in MB<sub>8</sub><sup>−</sup> clusters; see {{cite journal|url=https://www.nature.com/articles/s41467-021-26785-9 |title=Monovalent lanthanide(I) in borozene complexes |journal=Nature Communications |volume=12 |page=6467 |year=2021 |last1=Li |first1=Wan-Lu |doi=10.1038/s41467-021-26785-9 |last2=Chen |first2=Teng-Teng |last3=Chen |first3=Wei-Jia |last4=Li |first4=Jun |last5=Wang |first5=Lai-Sheng}}</ref>|note= |datacheck=yes}}
{{List of oxidation states of the elements/row |symbol=Ce |os= +2, +3b, +4b|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Pr |os= 0, +1, +2, +3b, +4, +5
|ref=<!--
--><ref name="Cloke1993"/><!--
--><ref>Pr(I) has been observed in [PrB<sub>4</sub>]<sup>−</sup>; see {{cite journal|last1=Chen|first1=Xin|last2=Chen|first2=Teng-Teng|last3=Li|first3=Wang-Lu|last4=Lu|first4=Jun-Bo|last5=Zhao|first5=Li-Juan|last6=Jian|first6=Tian|last7=Hu|first7=Han-Shi|last8=Wang|first8=Lai-Sheng|last9=Li|first9=Jun|date=2018-12-13|title=Lanthanides with Unusually Low Oxidation States in the PrB<sub>3</sub><sup>–</sup> and PrB<sub>4</sub><sup>–</sup> Boride Clusters|journal=Inorganic Chemistry|volume=58|issue=1|pages=411–418|doi=10.1021/acs.inorgchem.8b02572|pmid=30543295|s2cid=56148031}}</ref><!--
--><ref>Pr(V) has been observed in [PrO<sub>2</sub>]<sup>+</sup>; see {{cite journal|last1=Zhang|first1=Qingnan|last2=Hu|first2=Shu-Xian|last3=Qu|first3=Hui|last4=Su|first4=Jing|last5=Wang|first5=Guanjun|last6=Lu|first6=Jun-Bo|last7=Chen|first7=Mohua|last8=Zhou|first8=Mingfei|last9=Li|first9=Jun|date=2016-06-06|title=Pentavalent Lanthanide Compounds: Formation and Characterization of Praseodymium(V) Oxides|journal=Angewandte Chemie International Edition|volume=55|issue=24|pages=6896–6900|doi=10.1002/anie.201602196|issn=1521-3773|pmid=27100273}}</ref><!--
--><ref>{{cite journal|last1=Hu|first1=Shu-Xian|last2=Jian|first2=Jiwen|last3=Su|first3=Jing|last4=Wu|first4=Xuan|last5=Li|first5=Jun|last6=Zhou|first6=Mingfei|date=2017|title=Pentavalent lanthanide nitride-oxides: NPrO and NPrO− complexes with N≡Pr triple bonds|journal=Chemical Science|language=en|volume=8|issue=5|pages=4035–4043|doi=10.1039/C7SC00710H|pmid=28580119|pmc=5434915|issn=2041-6520}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Nd |os= 0, +2, +3b, +4
|ref=<!--
--><ref name="Cloke1993"/><!--
--><ref>Nd(IV) has been observed in unstable solid state compounds; see {{Holleman&Wiberg|p=1704}}</ref> |note= |datacheck=yes }} 
{{List of oxidation states of the elements/row |symbol=Pm |os= +2, +3b
|ref=<!--
--><ref name="Lanthanides">All the [[lanthanide]]s (La–Lu) in the +2 oxidation state have been observed (except La, Gd, Lu) in dilute, solid solutions of dihalides of these elements in alkaline earth dihalides (see {{Holleman&Wiberg|p=1704}}) and (except Pm) in organometallic molecular complexes, see [http://cen.acs.org/articles/91/i24/Lanthanides-Topple-Assumptions.html Lanthanides Topple Assumptions] and {{cite journal|doi=10.1002/anie.201311325|title=All the Lanthanides Do It and Even Uranium Does Oxidation State +2|year=2014|last1=Meyer|first1=G.|journal=Angewandte Chemie International Edition|volume=53|issue=14|pages=3550–51|pmid=24616202}}. Additionally, all the [[lanthanide]]s (La–Lu) form dihydrides (LnH<sub>2</sub>), dicarbides (LnC<sub>2</sub>), monosulfides (LnS), monoselenides (LnSe), and monotellurides (LnTe), but for most elements these compounds have Ln<sup>3+</sup> ions with electrons delocalized into conduction bands, e. g. Ln<sup>3+</sup>(H<sup>−</sup>)<sub>2</sub>(e<sup>−</sup>).</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Sm |os= 0, +1, +2, +3b
|ref=<!--
--><ref>SmB6- cluster anion has been reported and contains Sm in rare oxidation state of +1; see {{cite journal| title=SmB<sub>6</sub><sup>–</sup> Cluster Anion: Covalency Involving f Orbitals 
|first1=J. Robinson |last1=Paul |first2=Zhang |last2=Xinxing |first3=McQueen |last3=Tyrel |first4=H. Bowen |last4=Kit |first5=N. Alexandrova |last5=Anastassia |journal=J. Phys. Chem. A 2017, 121, 8, 1849–1854 |year = 2017|volume = 121|issue = 8|pages = 1849–1854|url=https://pubs.acs.org/doi/abs/10.1021/acs.jpca.7b00247#}}.</ref> |note= |datacheck=yes }} 
{{List of oxidation states of the elements/row |symbol=Eu |os= 0, +2b, +3b|ref=<!--
--><ref name="Cloke1993"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Gd |os= 0, +1, +2, +3b
|ref=<!--
--><ref name="Cloke1993"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Tb |os= 0, +1, +2, +3b, +4
|ref=<!--
--><ref name="Cloke1993"/><ref name=LnI/><!--
--><ref name="Lanthanides"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Dy |os= 0, +2, +3b, +4
|ref=<!----><ref name="Cloke1993"/><!--
--><ref>Dy(IV) has been observed in unstable solid state compounds; see {{Holleman&Wiberg|p=1704}}</ref> |note= |datacheck=yes }} 
{{List of oxidation states of the elements/row |symbol=Ho |os= 0, +2, +3b
|ref=<!--
--><ref name="Cloke1993"/><!--
--><ref name="Lanthanides"/> |note= |datacheck=yes }} 
{{List of oxidation states of the elements/row |symbol=Er |os= 0, +2, +3b
|ref=<!--
--><ref name="Cloke1993"/><!--
--><ref name="Lanthanides"/> |note= |datacheck=yes }} 
{{List of oxidation states of the elements/row |symbol=Tm |os= 0, +1, +2, +3b|ref=<!--
--><ref name="Cloke1993"/><ref name=LnI/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Yb |os= 0, +1, +2, +3b|ref=<!--
--><ref name="Cloke1993"/><ref name=LnI/>  |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Lu |os= 0, +2, +3b
|ref=<!--
--><ref name="Cloke1993"/><!--
--><ref name="Lanthanides"/> |note= |datacheck=yes }} 
{{List of oxidation states of the elements/row |symbol=Hf |os= −2, 0, +1, +2, +3, +4b
|ref=<!--
--><ref name="Carbonyls"/><!--
--><ref name="Zr0"/><!--
--><ref>Hf(I) has been observed in hafnium monobromide (HfBr), see {{cite journal
 | title= Кристаллическое строение и термодинамические характеристики монобромидов циркония и гафния / Crystal structure and thermodynamic characteristics of monobromides of zirconium and hafnium
 | last1= Marek | first1= G.S. | last2= Troyanov | first2= S.I. | last3= Tsirel'nikov | first3= V.I. | journal= Журнал неорганической химии / Russian Journal of Inorganic Chemistry | year= 1979 | volume= 24 | issue= 4 | pages= 890–893 | language= ru | url= https://inis.iaea.org/search/search.aspx?orig_q=RN:11520917}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ta |os= −3, −1, 0, +1, +2, +3, +4, +5b
|ref=<!--
--><ref name="Carbonyls"/><!--
--><ref name="NbTa"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=W  |os= −4, −2, −1, 0, +1, +2, +3, +4b, +5, +6b
|ref=<!--
--><ref name="Carbonyls"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Re |os= −3, −1, 0, +1, +2, +3, +4b, +5, +6, +7b
|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Os |os= −4, −2, −1, 0, +1, +2, +3, +4b, +5, +6, +7, +8
|ref=<!--
--><ref name="MetalAnions"/><!--
--><ref>Os(−1) has been observed in {{chem|Na[Os(CO)|13|]}}; see {{cite journal|doi=10.1016/0022-328X(93)83250-Y|title=Preparation of [Os<sub>3</sub>(CO)<sub>11</sub>]<sup>2−</sup> and its reactions with Os<sub>3</sub>(CO)<sub>12</sub>; structures of [Et<sub>4</sub>N] [HOs<sub>3</sub>(CO)<sub>11</sub>] and H<sub>2</sub>OsS<sub>4</sub>(CO)|year=1993|last1= Krause|first1=J.|journal=Journal of Organometallic Chemistry|volume=454|pages=263–271|last2=Siriwardane|first2=Upali|last3=Salupo|first3=Terese A.|last4=Wermer|first4=Joseph R.|last5=Knoeppel|first5=David W.|last6=Shore|first6=Sheldon G.|issue=1–2}} and {{cite journal|doi=10.1021/ic00141a019|title=Mononuclear hydrido alkyl carbonyl complexes of osmium and their polynuclear derivatives|year=1982|first=Willie J.|last=Carter|author2=Kelland, John W. |author3=Okrasinski, Stanley J. |author4=Warner, Keith E. |author5= Norton, Jack R. | journal=Inorganic Chemistry|volume=21|issue=11|pages=3955–3960}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ir |os= −3, −1, 0, +1, +2, +3b, +4b, +5, +6, +7, +8, +9
|ref=<!--
--><ref>Ir(−3) has been observed in Ir(CO)<sub>3</sub><sup>3−</sup>; see {{Greenwood&Earnshaw|page=1117}}</ref><!----><ref>Ir(VII) has been observed in [(η<sup>2</sup>-O<sub>2</sub>)IrO<sub>2</sub>]<sup>+</sup>; see [http://2014.cenmag.org/iridium-dressed-to-the-nines/ C&EN: Iridium dressed to the nines].</ref><!----><ref>Ir(VIII) has been observed in [[iridium tetroxide]] (IrO<sub>4</sub>); see {{cite journal|doi=10.1002/anie.200902733|pmid=19593837|title=Formation and Characterization of the Iridium Tetroxide Molecule with Iridium in the Oxidation State +VIII|year=2009|last1=Gong|first1=Yu|last2=Zhou|first2=Mingfei|last3=Kaupp|first3=Martin|last4=Riedel|first4=Sebastian|journal=Angewandte Chemie International Edition|volume=48|issue=42|pages=7879–7883}}</ref><!--
--><ref>Ir(IX) has been observed in {{chem|IrO|4|+}}; see {{cite journal |last1=Wang |first1=Guanjun |last2=Zhou |first2=Mingfei |last3=Goettel |first3=James T. |last4=Schrobilgen |first4=Gary G. |last5=Su |first5=Jing |last6=Li |first6=Jun |last7=Schlöder |first7=Tobias |last8=Riedel |first8=Sebastian |date=21 August 2014 |title=Identification of an iridium-containing compound with a formal oxidation state of IX |journal=Nature |volume=514 |issue=7523 |pages=475–477 |doi=10.1038/nature13795 |pmid=25341786|bibcode=2014Natur.514..475W|s2cid=4463905 }}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Pt |os= −3, −2, −1, 0, +1, +2b, +3, +4b, +5, +6
|ref=<!----><ref name="MetalAnions"/><!--
--><ref>Pt(−1) and Pt(−2) have been observed in the [[barium]] platinides BaPt and Ba<sub>2</sub>Pt, respectively: see {{cite journal |doi= 10.1039/b514631c |pmid= 16479284 |title= An experimental proof for negative oxidation states of platinum: ESCA-measurements on barium platinides|first1=Andrey |last1= Karpov |first2=Mitsuharu |last2=Konuma|first3=Martin |last3=Jansen|journal= Chemical Communications|year= 2006 |issue= 8|pages= 838–840}}</ref><!--
--><ref>Pt(I) and Pt(III) have been observed in bimetallic and polymetallic species; see {{cite book|title= Ammonium Hexachloroplatinate(IV)|first1= George B.|last1= Kauffman|author-link= George B. Kauffman |year= 1967|volume= 9 |pages= 182–185|doi= 10.1002/9780470132401.ch51|last2= Thurner|first2= Joseph J.|last3= Zatko|first3= David A.|series= Inorganic Syntheses|isbn= 978-0-470-13240-1}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Au |os= −3, −2, −1, 0, +1b, +2, +3b, +5|
|ref=<!----><ref name="MetalAnions"/><!--
--><ref>Au(0) has been observed, see {{cite journal |doi= 10.1002/(SICI)1521-3773(19991102)38:21<3194::AID-ANIE3194>3.0.CO;2-O |title= Gold(I) and Gold(0) Complexes of Phosphinine‐Based Macrocycles|first1=Nicolas |last1= Mézaille |first2=Narcis |last2=Avarvari |first3=Nicole |last3=Maigrot|first4=Louis |last4=Ricard|first5=François |last5=Mathey|first6=Pascal |last6=Le Floch|first7=Laurent|last7=Cataldo|first8=Théo|last8=Berclaz|first9=Michel|last9=Geoffroy|journal= Angewandte Chemie International Edition|year= 1999 |volume= 38|issue= 21|pages= 3194–3197|pmid= 10556900}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Hg |os= −2, +1b, +2b
|ref=<!----><ref name="MetalAnions"/><!--
--><ref>Hg(IV) has been reported in [[mercury(IV) fluoride]] (HgF<sub>4</sub>); see {{cite journal |author1=Xuefang Wang |author2=Lester Andrews |author3=Sebastian Riedel |author4= Martin Kaupp |title=Mercury Is a Transition Metal: The First Experimental Evidence for HgF<sub>4</sub> |journal=Angew. Chem. Int. Ed. |year=2007 |volume=46 |issue=44 |pages=8371–8375 |doi=10.1002/anie.200703710 |pmid=17899620}} However, it could not be confirmed by later experiments; see [http://www2.hull.ac.uk/science/chemistry/research/inorganicmaterials/mercurytransitionmaterial.aspx Is mercury a transition metal?] {{webarchive|url=https://web.archive.org/web/20161012232329/http://www2.hull.ac.uk/science/chemistry/research/inorganicmaterials/mercurytransitionmaterial.aspx |date=2016-10-12}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Tl |os= −5, −2, −1, +1b, +2, +3b
|ref=<!--
--><ref name="Zintl"/><!--
--><ref>Tl(−5) has been observed in Na<sub>23</sub>K<sub>9</sub>Tl<sub>15.3</sub>, see {{cite journal|doi=10.1021/ic960014z|title=Na<sub>23</sub>K<sub>9</sub>Tl<sub>15.3</sub>: An Unusual Zintl Compound Containing Apparent Tl<sub>5</sub><sup>7−</sup>, Tl<sub>4</sub><sup>8−</sup>, Tl<sub>3</sub><sup>7−</sup>, and Tl<sup>5−</sup> Anions|year=1996|last1=Dong|first1=Z.-C.|last2=Corbett|first2=J. D.|journal=Inorganic Chemistry|volume=35|issue=11|pages=3107–12|pmid=11666505}}</ref><!----><ref>Tl(−1) has been observed in [[caesium thallide]] (CsTl); see {{cite book|first1=R. B.|last1=King|first2=R.|last2=Schleyer|year=2004|chapter=Theory and concepts in main-group cluster chemistry|editor1-first=M.|editor1-last=Driess|editor2-first=H.|editor2-last=Nöth|title=Molecular clusters of the main group elements|publisher=Wiley-VCH, Chichester|page=19|isbn=978-3-527-61437-0}}</ref><!----><ref>Tl(+2) has been observed in [[tetrakis(hypersilyl)dithallium]] ([([[methyl|Me]]<sub>3</sub>Si)Si]<sub>2</sub>Tl—Tl[Si(SiMe<sub>3</sub>)]<sub>2</sub>), see {{cite journal |author=Sonja Henkel |author2=Dr. Karl Wilhelm Klinkhammer |author3=Dr. Wolfgang Schwarz |title=Tetrakis(hypersilyl)dithallium(Tl—Tl): A Divalent Thallium Compound |journal=Angew. Chem. Int. Ed. |year=1994 |volume=33 |issue=6 |pages=681–683 |doi=10.1002/anie.199406811}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Pb |os= −4, −2, −1, 0, +1, +2b, +3, +4b
|ref=<!--
--><ref name="Zintl"/><!--
--><ref>Pb(−2) has been observed in BaPb, see {{cite book |title= Intermetallic Chemistry |first1= Riccardo |last1= Ferro |editor= Nicholas C. Norman |publisher= Elsevier |year= 2008 |isbn= 978-0-08-044099-6 |page= 505}} and {{cite journal|doi=10.1021/ic000333x|title=Heavy-Metal Aromatic Rings: Cyclopentadienyl Anion Analogues Sn<sub>5</sub><sup>6−</sup> and Pb<sub>5</sub><sup>6−</sup> in the Zintl Phases Na<sub>8</sub>BaPb<sub>6</sub>, Na<sub>8</sub>BaSn<sub>6</sub>, and Na<sub>8</sub>EuSn<sub>6</sub>|year=2004|last1=Todorov|first1=Iliya|last2=Sevov|first2=Slavi C.|journal=Inorganic Chemistry|volume=43|issue=20|pages=6490–94}}</ref><!--
--><ref>Pb(0) carbonyls have been observered in reaction between lead atoms and [[carbon monoxide]]; see {{cite journal|url=https://aip.scitation.org/doi/10.1063/1.1834915 | title= Observation of the lead carbonyls Pb<sub>n</sub>CO (n=1–4): Reactions of lead atoms and small clusters with carbon monoxide in solid argon
|first1=Jiang |last1=Ling |first2=Xu |last2=Qiang |archive-date=2005-01-15 |journal=The Journal of Chemical Physics. 122 (3): 034505 |year = 2005|volume = 122|issue = 3|page = 34505|doi=10.1063/1.1834915 |pmid = 15740207|bibcode = 2005JChPh.122c4505J|issn=0021-9606}}</ref><!--
--><ref>Pb(+1) and Pb(+3) have been observed in [[organolead compounds]], e.g. hexamethyldiplumbane Pb<sub>2</sub>(CH<sub>3</sub>)<sub>6</sub>; for Pb(I), see {{cite journal |author=Siew-Peng Chia |author2=Hong-Wei Xi |author3=Yongxin Li |author4=Kok Hwa Lim |author5=Cheuk-Wai So |title=A Base-Stabilized Lead(I) Dimer and an Aromatic Plumbylidenide Anion |journal=Angew. Chem. Int. Ed. |year=2013 |volume=52 |issue=24 |pages=6298–6301 |doi=10.1002/anie.201301954|pmid=23629949}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Bi |os= −3, −2, −1, 0, +1, +2, +3b, +4, +5
|ref=<!----><ref>Bi(−2) and Bi(−1) occur in Zintl phases, e.g. (Ca<sup>2+</sup>)<sub>22</sub>[Bi<sub>4</sub>]<sup>4−</sup>([Bi<sub>2</sub>]<sup>4−</sup>)<sub>4</sub>[Bi<sup>3−</sup>]<sub>8</sub>; see {{cite news |title= Germanides, Germanide-Tungstate Double Salts and Substitution Effects in Zintl Phases |first1= Siméon |last1= Ponou |publisher= Technische Universität München. Lehrstuhl für Anorganische Chemie mit Schwerpunkt Neue Materialien |year= 2006 |url= http://d-nb.info/985527676/34?origin=publication_detailSim |page= 68}}</ref><!--
--><ref>Bi(0) state is known to exist in a [[Heterocyclic compound|N-heterocyclic carbene]] complex of dibismuthene; see {{cite journal |first1=Rajesh |last1=Deka |first2=Andreas |last2=Orthaber |title=Carbene chemistry of arsenic, antimony, and bismuth: origin, evolution and future prospects |journal=Royal Society of Chemistry |issue=51 |page=8540 |date=May 6, 2022 |doi=10.1039/d2dt00755j |url=https://europepmc.org/article/med/35578901}}</ref><!--
--><ref>Bi(I) has been observed in [[bismuth monobromide]] (BiBr) and [[bismuth monoiodide]] (BiI); see {{cite book |title= Chemistry of arsenic, antimony, and bismuth |first1= S. M. |last1= Godfrey |first2= C. A. |last2= McAuliffe |first3= A. G. |last3= Mackie |first4= R. G. |last4= Pritchard |editor= Nicholas C. Norman |publisher= Springer |year= 1998 |isbn= 978-0-7514-0389-3 |pages= 67–84}}</ref><!--
--><ref>Bi(+2) has been observed in [[dibismuthine]]s (R<sub>2</sub>Bi—BiR<sub>2</sub>), see {{cite book |author=Arthur J. Ashe III |title=Thermochromic Distibines and Dibismuthines |journal=Advances in Organometallic Chemistry |year=1990 |volume=30 |pages=77–97 |doi=10.1016/S0065-3055(08)60499-2|isbn=9780120311309}}</ref><!--
--><ref>Bi(IV) has been observed; see {{cite journal |author=A. I. Aleksandrov, I. E. Makarov |title=Formation of Bi(II) and Bi(IV) in aqueous hydrochloric solutions of Bi(III) |journal=Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science |year=1987 |volume=36 |issue=2 |pages=217–220 |doi=10.1007/BF00959349|s2cid=94865394 }}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Po |os= −2b, +2b, +4b, +5, +6
|ref=<!--
--><ref>Po(V) has been observed in [[dioxidopolonium(1+)]] ({{chem|PoO+}}); see {{cite book |last=Thayer |first=John S.|doi=10.1007/978-1-4020-9975-5_2 |year=2010 |page=78|title= Relativistic Methods for Chemists|isbn= 978-1-4020-9974-8|chapter= Relativistic Effects and the Chemistry of the Heavier Main Group Elements|series=Challenges and Advances in Computational Chemistry and Physics|volume=10}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=At |os= −1b, +1b, +3, +5, +7
|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Rn |os= +2b, +6
|ref=<!--
--><ref>Rn(II) has been observed in [[radon difluoride]] (RnF<sub>2</sub>); see {{cite journal |author= Stein, L. |year= 1970 |journal= Science |volume= 168 |pages= 362–4 |doi= 10.1126/science.168.3929.362 |title= Ionic Radon Solution |pmid= 17809133 |issue= 3929 |bibcode=1970Sci...168..362S|s2cid= 31959268 }} and {{cite journal |author= Kenneth S. Pitzer |year= 1975 |journal= J. Chem. Soc., Chem. Commun. |pages= 760b – 761 |title= Fluorides of radon and element 118 |doi= 10.1039/C3975000760b |issue= 18|url= https://escholarship.org/uc/item/8xz4g1ff }}</ref><!----><ref>Rn(IV) is reported by Greenwood and Earnshaw, but is not known to exist; see {{cite book |last=Sykes |first=A. G. |title=Advances in Inorganic Chemistry |volume=46 |chapter=Recent Advances in Noble-Gas Chemistry |chapter-url=https://books.google.com/books?id=6iqXRtz6p3QC |access-date=22 November 2012 |year=1998 |publisher=Academic Press |isbn=978-0-12-023646-6 |pages=91–93}}</ref><!--
--><ref>Rn(VI) is known in [[radon trioxide]] (RnO<sub>3</sub>); see {{cite book |last=Sykes |first=A. G. |title=Advances in Inorganic Chemistry |volume=46 |chapter=Recent Advances in Noble-Gas Chemistry |chapter-url=https://books.google.com/books?id=6iqXRtz6p3QC |access-date=22 November 2012 |year=1998 |publisher=Academic Press |isbn=978-0-12-023646-6 |pages=91–93}}</ref> |note= |datacheck=yes }}
<!--- Period 7 --->
{{List of oxidation states of the elements/row |symbol=Fr |os= +1b|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ra |os= +2b|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ac |os= +2, +3b|ref=<ref>Ac(II) is known in Actinium(II) hydride (AcH<sub>2</sub>); see {{cite journal |doi=10.1016/0022-1902(61)80369-2 |last1=Farr |date=1961 |first1=J. |pages=42–47 |volume=18 |journal=Journal of Inorganic and Nuclear Chemistry |title=The crystal structure of actinium metal and actinium hydride |last2=Giorgi |first2=A. L. |last3=Bowman |first3=M. G. |last4=Money |first4=R. K.|osti=4397640 }}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Th |os= -1, +1, +2, +3, +4b
|ref=<!--
--><ref>Th(-I) and U(-I) have been detected in the gas phase as octacarbonyl anions; see {{cite journal| title=Octacarbonyl Ion Complexes of Actinides [An(CO)<sub>8</sub>]<sup>+/−</sup> (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding 
|first1=Chi |last1=Chaoxian |first2=Pan |last2=Sudip |first3=Jin |last3=Jiaye |first4=Meng |last4=Luyan |first5=Luo |last5=Mingbiao |first6=Zhao |last6=Lili |first7=Zhou |last7=Mingfei |first8=Frenking |last8=Gernot |journal=Chemistry (Weinheim an der Bergstrasse, Germany). 25 (50): 11772–11784 |year = 2019|volume = 25|issue = 50|pages = 11772–11784|doi=10.1002/chem.201902625 |issn=0947-6539 |pmc=6772027
|pmid=31276242}}</ref><!----><ref>Th(I) is known in thorium(I) bromide (ThBr); see {{cite book|last1=Wickleder |first1=Mathias S. |first2=Blandine |last2=Fourest |first3=Peter K. |last3=Dorhout |ref=Wickleder et al. |contribution=Thorium |title=The Chemistry of the Actinide and Transactinide Elements |editor1-first=Lester R. |editor1-last=Morss |editor2-first=Norman M. |editor2-last=Edelstein |editor3-first=Jean |editor3-last=Fuger |edition=3rd |year=2006 |volume=3 |publisher=Springer |location=Dordrecht, the Netherlands |pages=52–160 |url=http://radchem.nevada.edu/classes/rdch710/files/thorium.pdf |doi=10.1007/1-4020-3598-5_3 |url-status=dead |archive-url=https://web.archive.org/web/20160307160941/http://radchem.nevada.edu/classes/rdch710/files/Thorium.pdf |archive-date=2016-03-07 |isbn=978-1-4020-3555-5}}</ref><!--
--><ref>Th(II) and Th(III) are observed in [Th<sup>II</sup>{''η''<sup>5</sup>-C<sub>5</sub>H<sub>3</sub>(SiMe<sub>3</sub>)<sub>2</sub>}<sub>3</sub>]<sup>−</sup> and [Th<sup>III</sup>{''η''<sup>5</sup>-C<sub>5</sub>H<sub>3</sub>(SiMe<sub>3</sub>)<sub>2</sub>}<sub>3</sub>], see {{cite journal |first1=Ryan R. |last1=Langeslay |first2=Megan E. |last2=Fieser |first3=Joseph W. |last3=Ziller |first4=Philip |last4=Furche |first5=William J. |last5=Evans |title=Synthesis, structure, and reactivity of crystalline molecular complexes of the {[C<sub>5</sub>H<sub>3</sub>(SiMe<sub>3</sub>)<sub>2</sub>]<sub>3</sub>Th}<sup>1−</sup> anion containing thorium in the formal +2 oxidation state |journal=Chem. Sci. |year=2015 |volume=6 |issue=1 |pages=517–521 |doi=10.1039/C4SC03033H|pmid=29560172 |pmc=5811171}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Pa |os= +2, +3, +4, +5b|ref=<!--
--><ref>Pa(II) occurs in proctactinium(II) oxide </ref>|note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=U  |os= -1, +1, +2, +3, +4b, +5, +6b
|ref=<!--
--><ref>Th(-I) and U(-I) have been detected in the gas phase as octacarbonyl anions; see {{cite journal| title=Octacarbonyl Ion Complexes of Actinides [An(CO)<sub>8</sub>]<sup>+/−</sup> (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding 
|first1=Chi |last1=Chaoxian |first2=Pan |last2=Sudip |first3=Jin |last3=Jiaye |first4=Meng |last4=Luyan |first5=Luo |last5=Mingbiao |first6=Zhao |last6=Lili |first7=Zhou |last7=Mingfei |first8=Frenking |last8=Gernot |journal=Chemistry (Weinheim an der Bergstrasse, Germany). 25 (50): 11772–11784 |year = 2019|volume = 25|issue = 50|pages = 11772–11784|doi=10.1002/chem.201902625 |issn=0947-6539 |pmc=6772027
|pmid=31276242}}</ref><!----><ref>U(I) has been observed in [[uranium monofluoride]] (UF) and [[uranium monochloride]] (UCl), see {{cite book |last=Sykes |first=A. G. |title=Advances in Inorganic Chemistry |volume=34 |chapter=Compounds of Thorium and Uranium |chapter-url=https://books.google.com/books?id=MZRm6E9LmgMC |access-date=22 March 2015 |year=1990 |publisher=Academic Press |isbn=978-0-12-023634-3 |pages=87–88}}</ref><!--
--><ref>U(II) has been observed in [K(2.2.2-Cryptand)][(C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub>)<sub>3</sub>U], see {{cite journal|doi=10.1021/ja406791t|pmid=23984753|title=Identification of the +2 Oxidation State for Uranium in a Crystalline Molecular Complex, [K(2.2.2-Cryptand)][(C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub>)<sub>3</sub>U]|year=2013|first1=Matthew R.|last1= MacDonald|first2=Megan E.|last2=Fieser|first3=Jefferson E.|last3=Bates|first4=Joseph W.|last4=Ziller|first5=Filipp|last5=Furche|first6=William J.|last6=Evans|journal=J. Am. Chem. Soc.|volume=135|issue=36|pages=13310–13313}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Np |os= +2, +3, +4, +5b, +6, +7
|ref=<!--
--><ref name="Dutkiewicz2017">Np(II), (III) and (IV) have been observed, see {{cite journal|doi=10.1039/C7SC00034K|pmid=28553487|pmc=5431675|year=2017|title=Reduction chemistry of neptunium cyclopentadienide complexes: from structure to understanding|first1=Michał S.|last1=Dutkiewicz|first2=Christos|last2=Apostolidis|first3=Olaf|last3=Walter|first4=Polly L|last4=Arnold|volume=8|issue=4|journal=Chem. Sci.|pages=2553–2561}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Pu |os= +2, +3, +4b, +5, +6, +7, +8
|ref=<!--
--><ref>Pu(II) has been observed in {Pu[C<sub>5</sub>H<sub>3</sub>(SiMe<sub>3</sub>)<sub>2</sub>]<sub>3</sub>}−; see {{cite journal|doi=10.1021/jacs.7b00706|pmid=28235179|title=Identification of the Formal +2 Oxidation State of Plutonium: Synthesis and Characterization ofref name="curium5" {Pu<sup>II</sup>[C<sub>5</sub>H<sub>3</sub>(SiMe<sub>3</sub>)<sub>2</sub>]<sub>3</sub>}−|year=2017|first1=Cory J.|last1=Windorff|first2=Guo P|last2=Chen|first3=Justin N|last3=Cross|first4=William J.|last4=Evans|first5=Filipp|last5= Furche|first6=Andrew J.|last6=Gaunt|first7=Michael T.|last7=Janicke|first8=Stosh A.|last8=Kozimor|first9=Brian L.|last9=Scott|journal=J. Am. Chem. Soc.|volume=139|issue=11|pages=3970–3973}}</ref><ref>Pu(VIII) has been observed in {{chem|Pu|O|4}}; see {{cite journal |last1=Nikonov |first1=M. V. |last2=Kiselev |first2=Yu. M. |last3=Tananaev |first3=I. G. |last4=Myasoedov |first4=B. F. |title=Plutonium volatility in ozonization of alkaline solutions of Pu(VI) hydroxo complexes |journal=Doklady Chemistry |date=March 2011 |volume=437 |issue=1 |pages=69–71 |doi=10.1134/S0012500811030104|s2cid=95951175 }} Also see {{cite journal |last1=Kiselev |first1=Yu. M. |last2=Nikonov |first2=M. V. |last3=Dolzhenko |first3=V. D. |last4=Ermilov |first4=A. Yu. |last5=Tananaev |first5=I. G. |last6=Myasoedov |first6=B. F. |title=On existence and properties of plutonium(VIII) derivatives |journal=Radiochimica Acta |date=17 January 2014 |volume=102 |issue=3 |pages=227–237 |doi=10.1515/ract-2014-2146|s2cid=100915090 }}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Am |os= +2, +3b, +4, +5, +6, +7
|ref=<!--
--><ref>Am(VII) has been observed in {{chem|AmO5-}}; see [http://www.chemie-master.de/FrameHandler.php?loc=http://www.chemie-master.de/pse/pse.php?modul=Am Americium], Das Periodensystem der Elemente für den Schulgebrauch (The periodic table of elements for schools) chemie-master.de (in German), Retrieved 28 November 2010 and {{Greenwood&Earnshaw|page=1265}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Cm |os= +3b, +4, +5, +6
|ref=<!--
--><ref name="Dau2017">Cm(V), Bk(V), and Cf(V) have been observed in BkO<sub>2</sub><sup>+</sup>, CfO<sub>2</sub><sup>+</sup>, CmO<sub>2</sub>(NO<sub>3</sub>)<sub>2</sub><sup>−</sup>, BkO<sub>2</sub>(NO<sub>3</sub>)<sub>2</sub><sup>−</sup>, and CfO<sub>2</sub>(NO<sub>3</sub>)<sub>2</sub><sup>−</sup>; see {{cite journal |last1=Dau |first1=Phuong Diem |last2=Vasiliu |first2=Monica |last3=Peterson |first3=Kirk A |last4=Dixon |first4=David A |last5=Gibsoon |first5=John K |date=October 2017 |title=Remarkably High Stability of Late Actinide Dioxide Cations: Extending Chemistry to Pentavalent Berkelium and Californium |journal=Chemistry - A European Journal |volume=23 |issue=68 |pages=17369–17378 |doi=10.1002/chem.201704193 |pmid=29024093 |url=http://www.escholarship.org/uc/item/1mk7j6ps }}</ref><!--
--><ref name="Kovács2018">{{cite journal |last1=Kovács |first1=Attila |last2=Dau |first2=Phuong D. |last3=Marçalo |first3=Joaquim |last4=Gibson |first4=John K. |date=2018 |title=Pentavalent Curium, Berkelium, and Californium in Nitrate Complexes: Extending Actinide Chemistry and Oxidation States |journal=Inorg. Chem. |volume=57 |issue=15 |pages=9453–9467 |publisher=American Chemical Society |doi=10.1021/acs.inorgchem.8b01450 |pmid=30040397 |osti=1631597 |s2cid=51717837 }}</ref><!--
--><ref>Cm(VI) has been observed in [[curium trioxide]] (CmO<sub>3</sub>) and dioxidocurium(2+) ({{chem|CmO2+}}); see {{cite journal |last1=Domanov |first1=V. P. |last2=Lobanov |first2=Yu. V. |date=October 2011 |title=Formation of volatile curium(VI) trioxide CmO<sub>3</sub> |journal=Radiochemistry |volume=53 |issue=5 |pages=453–6 |doi=10.1134/S1066362211050018|s2cid=98052484 }}</ref><!--
--><ref>Cm(VIII) has been reported to possibly occur in [[curium tetroxide]] (CmO<sub>4</sub>); see {{cite journal |last1=Domanov |first1=V. P. |date=January 2013 |title=Possibility of generation of octavalent curium in the gas phase in the form of volatile tetraoxide CmO<sub>4</sub> |journal=Radiochemistry |volume=55 |issue=1 |pages=46–51 |doi=10.1134/S1066362213010098|s2cid=98076989 }} However, new experiments seem to indicate its nonexistence: {{cite journal |last1=Zaitsevskii |first1=Andréi |last2=Schwarz |first2=W H Eugen |date=April 2014 |title=Structures and stability of AnO4 isomers, An = Pu, Am, and Cm: a relativistic density functional study |journal=Physical Chemistry Chemical Physics |volume=2014 |issue=16 |pages=8997–9001 |doi=10.1039/c4cp00235k |pmid=24695756 |bibcode=2014PCCP...16.8997Z}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Bk |os= +2, +3b, +4, +5
|ref=<!--
--><ref name="Dau2017"/><!--
--><ref name="Kovács2018"/><!--
--><ref name="Peterson">{{cite book|last1=Peterson|first1=J. R.|last2=Hobart|first2=D. E.|chapter-url=https://books.google.com/books?id=U-YOlLVuV1YC&pg=PA29|chapter=The Chemistry of Berkelium|editor-last=Emeléus|editor-first=Harry Julius|title=Advances in inorganic chemistry and radiochemistry|volume=28|publisher=Academic Press|date=1984|isbn=978-0-12-023628-2|pages=[https://archive.org/details/advancesininorga0000unse_p1d0/page/29 29–64]|doi=10.1016/S0898-8838(08)60204-4|url=https://archive.org/details/advancesininorga0000unse_p1d0/page/29}}</ref>{{sfn|Peterson|1984|p=55}}<!--
--><ref>{{cite journal|last1=Sullivan|first1=Jim C.|last2=Schmidt|first2=K. H.|last3=Morss|first3=L. R.|last4=Pippin|first4=C. G.|last5=Williams|first5=C.|title=Pulse radiolysis studies of berkelium(III): preparation and identification of berkelium(II) in aqueous perchlorate media|journal=Inorganic Chemistry|volume=27|pages=597|date=1988|doi=10.1021/ic00277a005|issue=4}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Cf |os= +2, +3b, +4, +5
|ref=<!--
--><ref name="Dau2017"/><!--
--><ref name="Kovács2018"/> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Es |os= +2, +3b, +4
|ref=<!--
--><ref>Es(IV) is known in [[einsteinium(IV) fluoride]] (EsF<sub>4</sub>); see {{cite journal|last1=Kleinschmidt|first1=P|title=Thermochemistry of the actinides|journal=Journal of Alloys and Compounds|volume=213–214|pages=169–172|year=1994|doi=10.1016/0925-8388(94)90898-2|url=https://digital.library.unt.edu/ark:/67531/metadc1401691/}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Fm |os= +2, +3b|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Md |os= +2, +3b|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=No |os= +2b, +3|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Lr |os= +3b|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Rf |os= +4b|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Db |os= +5b
|ref=<!--
--><ref>Db(V) has been observed in dubnium pentachloride (DbCl<sub>5</sub>); see {{cite web|author=H. W. Gäggeler |title=Gas Phase Chemistry of Superheavy Elements |year=2007 |pages=26–28 |publisher=[[Paul Scherrer Institute]] |url=http://lch.web.psi.ch/files/lectures/TexasA&M/TexasA&M.pdf |url-status=dead |archive-url=https://web.archive.org/web/20120220090755/http://lch.web.psi.ch/files/lectures/TexasA%26M/TexasA%26M.pdf |archive-date=2012-02-20 }}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Sg |os= 0, +6b
|ref=<!--
--><ref>Sg(VI) has been observed in seaborgium oxide hydroxide (SgO<sub>2</sub>(OH)<sub>2</sub>); see {{cite journal|url=http://www-w2k.gsi.de/kernchemie/images/pdf_Artikel/Radiochim_Acta_89_737_2001.pdf |title=Physico-chemical characterization of seaborgium as oxide hydroxide |journal=Radiochim. Acta |volume=89 |pages=737–741 |year=2001 |doi=10.1524/ract.2001.89.11-12.737 |last1=Huebener |first1=S. |last2=Taut |first2=S. |last3=Vahle |first3=A. |last4=Dressler |first4=R. |last5=Eichler |first5=B. |last6=Gäggeler |first6=H. W. |last7=Jost |first7=D.T. |last8=Piguet |first8=D. |last9=Türler |first9=A. |last10=Brüchle |first10=W. |issue=11–12_2001 |s2cid=98583998 |display-authors=8 |url-status=dead |archive-url=https://web.archive.org/web/20141025201143/http://www-w2k.gsi.de/kernchemie/images/pdf_Artikel/Radiochim_Acta_89_737_2001.pdf |archive-date=2014-10-25}}</ref><!--
--><ref>Sg(0) has been observed in seaborgium hexacarbonyl (Sg(CO)<sub>6</sub>); see {{Cite journal |doi=10.1126/science.1255720 |pmid=25237098 |title=Synthesis and detection of a seaborgium carbonyl complex |journal=Science |volume=345 |issue=6203 |pages=1491–3 |year=2014 |last1=Even |first1=J. | last2=Yakushev | first2=A.| last3=Dullmann | first3=C. E.| last4=Haba | first4=H.| last5=Asai | first5=M.| last6=Sato | first6=T. K.| last7=Brand | first7=H.| last8=Di Nitto | first8=A.| last9=Eichler | first9=R.| last10=Fan | first10=F. L.| last11=Hartmann | first11=W.| last12=Huang | first12=M.| last13=Jager | first13=E.| last14=Kaji | first14=D.| last15=Kanaya | first15=J.| last16=Kaneya | first16=Y.| last17=Khuyagbaatar | first17=J.| last18=Kindler | first18=B.| last19=Kratz | first19=J. V.| last20=Krier | first20=J.| last21=Kudou | first21=Y.| last22=Kurz | first22=N.| last23=Lommel | first23=B.| last24=Miyashita | first24=S.| last25=Morimoto | first25=K.| last26=Morita | first26=K.| last27=Murakami | first27=M.| last28=Nagame | first28=Y.| last29=Nitsche | first29=H.| last30=Ooe | first30=K.| display-authors=29| bibcode=2014Sci...345.1491E|s2cid=206558746 }}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Bh |os= +7b
|ref=<!--
--><ref>Bh(VII) has been observed in bohrium oxychloride (BhO<sub>3</sub>Cl); see [http://www.gsi.de/informationen/wti/library/scientificreport2000/Chemistry/9/r_eichler_jb2000.pdf "Gas chemical investigation of bohrium (Bh, element 107)"] {{webarchive|url=https://web.archive.org/web/20080228023225/http://www.gsi.de/informationen/wti/library/scientificreport2000/Chemistry/9/r_eichler_jb2000.pdf |date=2008-02-28}}, Eichler et al., ''GSI Annual Report 2000''. Retrieved on 2008-02-29</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Hs |os= +8b
|ref=<!--
--><ref>Hs(VIII) has been observed in hassium tetroxide (HsO<sub>4</sub>); see {{cite web|url=http://www.gsi.de/documents/DOC-2003-Jun-29-2.pdf|title=Chemistry of Hassium|access-date=2007-01-31|year=2002|website=Gesellschaft für Schwerionenforschung mbH}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Mt |os=|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ds |os=|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Rg |os=|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Cn |os= +2b
|ref=<!--
--><ref>Cn(II) has been observed in copernicium selenide (CnSe); see {{cite web|year=2015|title=Annual Report 2015: Laboratory of Radiochemistry and Environmental Chemistry|url=https://www.psi.ch/luc/AnnualReportsEN/PSI_LCH_AnnualReport2015.pdf|page=3|publisher=Paul Scherrer Institute}}</ref> |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Nh |os=|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Fl |os=|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Mc |os=|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Lv |os=|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Ts |os=|ref= |note= |datacheck=yes }}
{{List of oxidation states of the elements/row |symbol=Og |os=|ref= |note= |datacheck=yes }}
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