^四唑環中有一對以雙鍵鍵結、氧化態為0的氮原子。母體1-H-四唑(CH2N4)的合成過程參見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.
^七氟化金實際上是五氟化金與氟分子(F2)形成的配合物。Himmel, Daniel; Riedel, Sebastian. After 20 Years, Theoretical Evidence That 'AuF7' Is Actually AuF5•F2. Inorganic Chemistry. 2007, 46 (13): 5338–5342. PMID 17511450. doi:10.1021/ic700431s.
^Ne(0)已在Cr(CO)5Ne中觀察到,參見:Perutz, Robin N.; Turner, James J. Photochemistry of the Group 6 hexacarbonyls in low-temperature matrices. III. Interaction of the pentacarbonyls with noble gases and other matrices. Journal of the American Chemical Society. August 1975, 97 (17): 4791–4800. doi:10.1021/ja00850a001.
^Al(−2)已在Sr14[Al4]2[Ge]3中觀察到,參見:Wemdorff, Marco; Röhr, Caroline. Sr14[Al4]2[Ge]3: Eine Zintl-Phase mit isolierten [Ge]4–- und [Al4]8–-Anionen / Sr14[Al4]2[Ge]3: A Zintl Phase with Isolated [Ge]4–- and [Al4]8– Anions. Zeitschrift für Naturforschung B. 2007, 62 (10): 1227. S2CID 94972243. doi:10.1515/znb-2007-1001(德语).
^P(0)已被觀察到,參見:Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; King, R. Bruce; Schaefer, Iii; Schleyer, Paul v. R.; Robinson, Gregory H. Carbene-Stabilized Diphosphorus. Journal of the American Chemical Society. 2008, 130 (45): 14970–1. PMID 18937460. doi:10.1021/ja807828t.
^Cl2O6⇌2ClO3反應的化學平衡曾被Greenwood & Earnshaw提及,但已被駁回。參見:Lopez, Maria; Juan E. Sicre. Physicochemical properties of chlorine oxides. 1. Composition, ultraviolet spectrum, and kinetics of the thermolysis of gaseous dichlorine hexoxide. J. Phys. Chem. 1990, 94 (9): 3860–3863. doi:10.1021/j100372a094., and Cl2O6 is actually chlorine(V,VII) oxide. However, ClO3 has been observed, see Grothe, Hinrich; Willner, Helge. Chlorine Trioxide: Spectroscopic Properties, Molecular Structure, and Photochemical Behavior. Angew. Chem. Int. Ed. 1994, 33 (14): 1482–1484. doi:10.1002/anie.199414821.
^Ca(I)已被觀察到,參見:Krieck, Sven; Görls, Helmar; Westerhausen, Matthias. Mechanistic Elucidation of the Formation of the Inverse Ca(I) Sandwich Complex [(thf)3Ca(μ-C6H3-1,3,5-Ph3)Ca(thf)3] and Stability of Aryl-Substituted Phenylcalcium Complexes. Journal of the American Chemical Society. 2010, 132 (35): 12492–501. PMID 20718434. doi:10.1021/ja105534w.
^Sc(0)已被觀察到,參見:F. Geoffrey N. Cloke; Karl Khan & Robin N. Perutz. η-Arene complexes of scandium(0) and scandium(II). J. Chem. Soc., Chem. Commun. 1991, (19): 1372–1373. doi:10.1039/C39910001372.
^Sc(I)已被觀察到,參見:Polly L. Arnold; F. Geoffrey; N. Cloke; Peter B. Hitchcock & John F. Nixon. 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. J. Am. Chem. Soc. 1996, 118 (32): 7630–7631. doi:10.1021/ja961253o.
^Sc(II)已被觀察到,參見:Woen, David H.; Chen, Guo P.; Ziller, Joseph W.; Boyle, Timothy J.; Furche, Filipp; Evans, William J. Solution Synthesis, Structure, and CO Reduction Reactivity of a Scandium(II) Complex. Angewandte Chemie International Edition. January 2017, 56 (8): 2050–2053. PMID 28097771. doi:10.1002/anie.201611758.
^Ti(−1)最初被報告存在於[Ti(bipy)3]− 中,但後來證明其為Ti(+3),參見Bowman, A. C.; England, J.; Sprouls, S.; Weihemüller, T.; Wieghardt, K. 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. Inorganic Chemistry. 2013, 52 (4): 2242–56. PMID 23387926. doi:10.1021/ic302799s. 不過,Ti(−1)被發現存在於[Ti(η-C6H6]−和[Ti(η-C6H5CH3)]−中, 參見:Bandy, J. A.; Berry, A.; Green, M. L. H.; Perutz, R. N.; Prout, K.; Verpeautz, J.-N. Synthesis of anionic sandwich compounds: [Ti(η-C6H5R)2]– and the crystal structure of [K(18-crown-6)(µ-H)Mo(η-C5H5)2]. Inorganic Chemistry. 1984, 52 (4): 729–731. doi:10.1039/C39840000729.
^Ti(I)已在[Ti(η6-1,3,5-C6H3iPr3)2][BAr4] (Ar = C6H5, p-C6H4F, 3,5-C6H3(CF3)2)中觀察到,參見:Calderazzo, Fausto; Ferri, Isabella; Pampaloni, Guido; Englert, Ulli; Green, Malcolm L. H. Synthesis of [Ti(η6-1,3,5-C6H3iPr3)2][BAr4] (Ar = C6H5, p-C6H4F, 3,5-C6H3(CF3)2), the First Titanium(I) Derivatives. Organometallics. 1997, 16 (14): 3100–3101. doi:10.1021/om970155o.
^Jilek, Robert E.; Tripepi, Giovanna; Urnezius, Eugenijus; Brennessel, William W.; Young, Victor G. Jr.; Ellis, John E. Zerovalent titanium–sulfur complexes. Novel dithiocarbamato derivatives of Ti(CO)6: [Ti(CO)4(S2CNR2)]−. Chem. Commun. 2007, (25): 2639–2641. PMID 17579764. doi:10.1039/B700808B.
^Fe(VII)已在[FeO4]−中觀察到,參見:Lu, Jun-Bo; Jian, Jiwen; Huang, Wei; Lin, Hailu; Zhou, Mingfei. Experimental and theoretical identification of the Fe(VII) oxidation state in FeO4−. Physical Chemistry Chemical Physics. 2016, 18 (45): 31125–31131. Bibcode:2016PCCP...1831125L. PMID 27812577. doi:10.1039/C6CP06753K.
^Fe(VIII)已被報告,參見:Yurii D. Perfiliev; Virender K. Sharma. Higher Oxidation States of Iron in Solid State: Synthesis and Their Mössbauer Characterization – Ferrates – ACS Symposium Series (ACS Publications). Platinum Metals Review. 2008, 48 (4): 157–158. doi:10.1595/147106704X10801. 然而,其存在與否一直有所爭議。
^ 36.0036.0136.0236.0336.0436.0536.0636.0736.0836.09Fe(−4)、Ru(−4)和Os(−4)已在含有八面體配合物[MIn6−xSnx]的富金屬化合物中觀察到;Pt(−3)(以二聚體陰離子[Pt–Pt]6−的形式)、Cu(−2)、Zn(−2)、Ag(−2)、Cd(−2)、Au(−2)和Hg(−2)(以二聚體和單體陰離子之形式;Zn、Cd、Hg的二聚體離子最初被報告為[T–T]2−的形式、但後來的研究顯示所有這些元素的二聚體陰離子皆為[T–T]4−形式)已在下列化合物中觀察到:La2Pt2In、La2Cu2In、Ca5Au3、Ca5Ag3、Ca5Hg3、Sr5Cd3、Ca5Zn3(結構為(AE2+)5(T–T)4−T2 −⋅4e−)、Yb3Ag2、Ca5Au4和Ca3Hg2;Au(-3)已在ScAuSn及其他18電子的半赫斯勒化合物(英语:Heusler compound)中觀察到。參見:Changhoon Lee; Myung-Hwan Whangbo. Late transition metal anions acting as p-metal elements. Solid State Sciences. 2008, 10 (4): 444–449. Bibcode:2008SSSci..10..444K. doi:10.1016/j.solidstatesciences.2007.12.001. and Changhoon Lee; Myung-Hwan Whangbo; Jürgen Köhler. Analysis of Electronic Structures and Chemical Bonding of Metal-rich Compounds. 2. Presence of Dimer (T–T)4– and Isolated T2– Anions in the Polar Intermetallic Cr5B3-Type Compounds AE5T3 (AE = Ca, Sr; T = Au, Ag, Hg, Cd, Zn). Zeitschrift für Anorganische und Allgemeine Chemie. 2010, 636 (1): 36–40. doi:10.1002/zaac.200900421.
^Ni(−2)已在Li2[Ni(1,5-COD)2]中觀察到,參見:Jonas, Klaus. Dilithium-Nickel-Olefin Complexes. Novel Bimetal Complexes Containing a Transition Metal and a Main Group Metal. Angew. Chem. Int. Ed. 1975, 14 (11): 752–753. doi:10.1002/anie.197507521. and Ellis, John E. Adventures with Substances Containing Metals in Negative Oxidation States. Inorganic Chemistry. 2006, 45 (8): 3167–86. PMID 16602773. doi:10.1021/ic052110i.
^As(0)已被觀察到,參見:Abraham, Mariham Y.; Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; Shaefer III, Henry F.; Schleyer, P. von R.; Robinson, Gregory H. Carbene Stabilization of Diarsenic: From Hypervalency to Allotropy. Chemistry: A European Journal. 2010, 16 (2): 432–5. PMID 19937872. doi:10.1002/chem.200902840.
^As(I)已在AsI中觀察到,參見:Ellis, Bobby D.; MacDonald, Charles L. B. Stabilized Arsenic(I) Iodide: A Ready Source of Arsenic Iodide Fragments and a Useful Reagent for the Generation of Clusters. Inorganic Chemistry. 2004, 43 (19): 5981–6. PMID 15360247. doi:10.1021/ic049281s.
^As(IV)已在As(OH)4及HAsO− 中觀察到,參見:Kläning, Ulrik K.; Bielski, Benon H. J.; Sehested, K. Arsenic(IV). A pulse-radiolysis study. Inorganic Chemistry. 1989, 28 (14): 2717–24. doi:10.1021/ic00313a007.
^ 56.0056.0156.0256.0356.0456.0556.0656.0756.0856.0956.1056.1156.12氧化態為0的釔和所有鑭系元素(鈰及鉕除外)已在雙(1,3,5-三叔丁基苯)錯合物中觀察到,參見:Cloke, F. Geoffrey N. Zero Oxidation State Compounds of Scandium, Yttrium, and the Lanthanides. Chem. Soc. Rev. 1993, 22: 17–24. doi:10.1039/CS9932200017. and Arnold, Polly L.; Petrukhina, Marina A.; Bochenkov, Vladimir E.; Shabatina, Tatyana I.; Zagorskii, Vyacheslav V.; Cloke. Arene complexation of Sm, Eu, Tm and Yb atoms: a variable temperature spectroscopic investigation. Journal of Organometallic Chemistry. 2003-12-15, 688 (1–2): 49–55. doi:10.1016/j.jorganchem.2003.08.028.
^Y(II)已在[(18-crown-6)K][(C5H4SiMe3)3Y]中觀察到,參見:MacDonald, M. R.; Ziller, J. W.; Evans, W. J. Synthesis of a Crystalline Molecular Complex of Y2+, [(18-crown-6)K][(C5H4SiMe3)3Y]. J. Am. Chem. Soc. 2011, 133 (40): 15914–17. PMID 21919538. doi:10.1021/ja207151y.
^Zr(−1)曾被報告存在於[Zr(bipy)3]−中(參見 Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements 2nd. Oxford:Butterworth-Heinemann. 1997: 960. ISBN 0-7506-3365-4. 及 Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils. Zirconium. Lehrbuch der Anorganischen Chemie 101. Walter de Gruyter. 1995: 1413. ISBN 978-3-11-012641-9(德语).), 但後來被證明是Zr(+4),參見:Bowman, A. C.; England, J.; Sprouls, S.; Weihemüller, T.; Wieghardt, K. 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. Inorganic Chemistry. 2013, 52 (4): 2242–56. PMID 23387926. doi:10.1021/ic302799s.
^ 60.060.1Zr(0)及Hf(0)出現在(η6-(1,3,5-tBu)3C6H3)2M (M=Zr, Hf)及[(η5-C5R5M(CO)4]−中,參見:Chirik, P. J.; Bradley, C. A. 4.06 - Complexes of Zirconium and Hafnium in Oxidation States 0 to ii. Comprehensive Organometallic Chemistry III. From Fundamentals to Applications 4. Elsevier Ltd. 2007: 697–739. ISBN 9780080450476. doi:10.1016/B0-08-045047-4/00062-5.
^Nb(0)及Ta(0)的配合物已被觀察到,參見:Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils. 4.5.7. Niobium(0) and Tantalum(0). J. A. McCleverty; T.J. Meyer (编). Comprehensive Coordination Chemistry II: From Biology to Nanotechnology 4 2. Newnes. 2003: 297–299. ISBN 978-0-08-091316-2.
^Pd(V)已被確認存在於含有五配位數鈀原子的有機矽化合物之絡合物中,參見:Shimada, Shigeru; Li, Yong-Hua; Choe, Yoong-Kee; Tanaka, Masato; Bao, Ming; Uchimaru, Tadafumi. Multinuclear palladium compounds containing palladium centers ligated by five silicon atoms. Proceedings of the National Academy of Sciences. 2007, 104 (19): 7758–7763. doi:10.1073/pnas.0700450104.
^Ag−離子已在金屬與液態氨之溶液中觀察到,參見:Tran, N. E.; Lagowski, J. J. Metal Ammonia Solutions: Solutions Containing Argentide Ions. Inorganic Chemistry. 2001, 40 (5): 1067–68. doi:10.1021/ic000333x.
^Ag(0)已在低溫基質隔離(英语:Matrix isolation)條件下的羰基絡合物中觀察到,參見McIntosh, D.; Ozin, G. A. 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. J. Am. Chem. Soc. 1976, 98 (11): 3167–75. doi:10.1021/ja00427a018.
^Cd(I)已在四氯鋁酸鎘(I)(Cd2(AlCl4)2)中觀察到,參見:Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils. Cadmium. Lehrbuch der Anorganischen Chemie 91–100. Walter de Gruyter. 1985: 1056–1057. ISBN 978-3-11-007511-3(德语).
^In(–5)已在La3InGe中觀察到,參見:Guloy, A. M.; Corbett, J. D. Synthesis, Structure, and Bonding of Two Lanthanum Indium Germanides with Novel Structures and Properties. Inorganic Chemistry. 1996, 35 (9): 2616–22. PMID 11666477. doi:10.1021/ic951378e.
^Sb(I)及Sb(II)已在有機銻化合物中觀察到;關於Sb(I),參見:Šimon, Petr; de Proft, Frank; Jambor, Roman; Růžička, Aleš; Dostál, Libor. Monomeric Organoantimony(I) and Organobismuth(I) Compounds Stabilized by an NCN Chelating Ligand: Syntheses and Structures. Angewandte Chemie International Edition. 2010, 49 (32): 5468–5471. PMID 20602393. doi:10.1002/anie.201002209.
^Sb(IV)已在[SbCl 6]2−中觀察到,參見:Nobuyoshi Shinohara; Masaaki Ohsima. Production of Sb(IV) Chloro Complex by Flash Photolysis of the Corresponding Sb(III) and Sb(V) Complexes in CH3CN and CHCl3. Bulletin of the Chemical Society of Japan. 2000, 73 (7): 1599–1604. doi:10.1246/bcsj.73.1599.
^Nd(IV)已在不穩定的固體化合物中觀察到,參見:Holleman, Arnold Frederik; Wiberg, Egon, Wiberg, Nils , 编, Inorganic Chemistry, 由Eagleson, Mary; Brewer, William翻译, San Diego/Berlin: Academic Press/De Gruyter, 2001, ISBN 0-12-352651-5
^ 97.097.197.297.397.4所有鑭系元素(鑭至鎦)的+2氧化態均已在其二鹵化物和鹼土金屬二鹵化物形成的稀固溶體中(參閱:Holleman, Arnold Frederik; Wiberg, Egon, Wiberg, Nils , 编, Inorganic Chemistry, 由Eagleson, Mary; Brewer, William翻译, San Diego/Berlin: Academic Press/De Gruyter, 2001, ISBN 0-12-352651-5,鑭、釓、鎦除外)以及其有機金屬分子錯合物中(鉕除外)觀察到,參見:Lanthanides Topple Assumptions (页面存档备份,存于互联网档案馆) and Meyer, G. All the Lanthanides Do It and Even Uranium Does Oxidation State +2. Angewandte Chemie International Edition. 2014, 53 (14): 3550–51. PMID 24616202. doi:10.1002/anie.201311325.。此外,雖然所有鑭系元素皆形成二氫化物(LnH2)、二碳化物(LnC2)、一硫化物(LnS)、一硒化物(LnSe)和一碲化物(LnTe),但對於大多數鑭系元素,這些化合物中的鑭系離子實為+3態,伴隨著離域至導帶的電子,例如:Ln3+(H−)2(e−)。
^SmB6-團簇陰離子已被報告,其中含有罕見的+1態釤,參見:Paul, J. Robinson; Xinxing, Zhang; Tyrel, McQueen; Kit, H. Bowen; Anastassia, N. Alexandrova. SmB6– Cluster Anion: Covalency Involving f Orbitals. J. Phys. Chem. A 2017, 121, 8, 1849–1854. 2017, 121 (8): 1849–1854 [2023-05-28]. (原始内容存档于2022-09-25)..
^Dy(IV)已在不穩定的固態化合物中觀察到,參見:Holleman, Arnold Frederik; Wiberg, Egon, Wiberg, Nils , 编, Inorganic Chemistry, 由Eagleson, Mary; Brewer, William翻译, San Diego/Berlin: Academic Press/De Gruyter, 2001, ISBN 0-12-352651-5
^Os(−1)已在Na[Os(CO) 13]中觀察到,參見:Krause, J.; Siriwardane, Upali; Salupo, Terese A.; Wermer, Joseph R.; Knoeppel, David W.; Shore, Sheldon G. Preparation of [Os3(CO)11]2− and its reactions with Os3(CO)12; structures of [Et4N] [HOs3(CO)11] and H2OsS4(CO). Journal of Organometallic Chemistry. 1993, 454 (1–2): 263–271. doi:10.1016/0022-328X(93)83250-Y. and Carter, Willie J.; Kelland, John W.; Okrasinski, Stanley J.; Warner, Keith E.; Norton, Jack R. Mononuclear hydrido alkyl carbonyl complexes of osmium and their polynuclear derivatives. Inorganic Chemistry. 1982, 21 (11): 3955–3960. doi:10.1021/ic00141a019.
^Ir(−3)已在Ir(CO)33−已在一溴化鉿 (HfBr) 中觀察到,參見:Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements 2nd. Oxford:Butterworth-Heinemann. 1997: 1117. ISBN 0-7506-3365-4.
^Ir(VIII)已在四氧化銥(IrO4)中觀察到,參見:Gong, Yu; Zhou, Mingfei; Kaupp, Martin; Riedel, Sebastian. Formation and Characterization of the Iridium Tetroxide Molecule with Iridium in the Oxidation State +VIII. Angewandte Chemie International Edition. 2009, 48 (42): 7879–7883. PMID 19593837. doi:10.1002/anie.200902733.
^Ir(IX)已在IrO+ 4中觀察到,參見:Wang, Guanjun; Zhou, Mingfei; Goettel, James T.; Schrobilgen, Gary G.; Su, Jing; Li, Jun; Schlöder, Tobias; Riedel, Sebastian. Identification of an iridium-containing compound with a formal oxidation state of IX. Nature. 21 August 2014, 514 (7523): 475–477. Bibcode:2014Natur.514..475W. PMID 25341786. S2CID 4463905. doi:10.1038/nature13795.
^Pt(−1)及Pt(−2)已分別在鋇的鉑化物BaPt及Ba2Pt中觀察到,參見:Karpov, Andrey; Konuma, Mitsuharu; Jansen, Martin. An experimental proof for negative oxidation states of platinum: ESCA-measurements on barium platinides. Chemical Communications. 2006, (8): 838–840. PMID 16479284. doi:10.1039/b514631c.
^Au(0)已被觀察到,參見:Mézaille, Nicolas; Avarvari, Narcis; Maigrot, Nicole; Ricard, Louis; Mathey, François; Le Floch, Pascal; Cataldo, Laurent; Berclaz, Théo; Geoffroy, Michel. Gold(I) and Gold(0) Complexes of Phosphinine‐Based Macrocycles. Angewandte Chemie International Edition. 1999, 38 (21): 3194–3197. PMID 10556900. doi:10.1002/(SICI)1521-3773(19991102)38:21<3194::AID-ANIE3194>3.0.CO;2-O.
^Hg(IV)曾被報告發現存在於四氟化汞(HgF4)中,參見:Xuefang Wang; Lester Andrews; Sebastian Riedel; Martin Kaupp. Mercury Is a Transition Metal: The First Experimental Evidence for HgF4. Angew. Chem. Int. Ed. 2007, 46 (44): 8371–8375. PMID 17899620. doi:10.1002/anie.200703710.但之後的實驗無法證實該發現,參閱:Is mercury a transition metal?互联网档案馆的存檔,存档日期2016-10-12.
^Tl(−5)已在Na23K9Tl15.3中觀察到,參見:Dong, Z.-C.; Corbett, J. D. Na23K9Tl15.3: An Unusual Zintl Compound Containing Apparent Tl57−, Tl48−, Tl37−, and Tl5− Anions. Inorganic Chemistry. 1996, 35 (11): 3107–12. PMID 11666505. doi:10.1021/ic960014z.
^Tl(−1)已在鉈化銫(CsTl)中觀察到,參見:King, R. B.; Schleyer, R. Theory and concepts in main-group cluster chemistry. Driess, M.; Nöth, H. (编). Molecular clusters of the main group elements. Wiley-VCH, Chichester. 2004: 19. ISBN 978-3-527-61437-0.
^Tl(+2)已在四(超甲矽烷基)二鉈([(Me3Si)Si]2Tl—Tl[Si(SiMe3)]2)中觀察到,參見:Sonja Henkel; Dr. Karl Wilhelm Klinkhammer; Dr. Wolfgang Schwarz. Tetrakis(hypersilyl)dithallium(Tl—Tl): A Divalent Thallium Compound. Angew. Chem. Int. Ed. 1994, 33 (6): 681–683. doi:10.1002/anie.199406811.
^Pb(−2)已在BaPb中觀察到,參見:Ferro, Riccardo. Nicholas C. Norman , 编. Intermetallic Chemistry. Elsevier. 2008: 505. ISBN 978-0-08-044099-6. and Todorov, Iliya; Sevov, Slavi C. Heavy-Metal Aromatic Rings: Cyclopentadienyl Anion Analogues Sn56− and Pb56− in the Zintl Phases Na8BaPb6, Na8BaSn6, and Na8EuSn6. Inorganic Chemistry. 2004, 43 (20): 6490–94. doi:10.1021/ic000333x.
^Bi(I)已在一溴化鉍(BiBr)及一碘化鉍(BiI)中觀察到,參見:Godfrey, S. M.; McAuliffe, C. A.; Mackie, A. G.; Pritchard, R. G. Nicholas C. Norman , 编. Chemistry of arsenic, antimony, and bismuth. Springer. 1998: 67–84. ISBN 978-0-7514-0389-3.
^Bi(IV)已被觀察到,參見:A. I. Aleksandrov, I. E. Makarov. Formation of Bi(II) and Bi(IV) in aqueous hydrochloric solutions of Bi(III). Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science. 1987, 36 (2): 217–220. S2CID 94865394. doi:10.1007/BF00959349.
^Po(V)已在dioxidopolonium(1+)(PoO+ )中觀察到,參見:Thayer, John S. Relativistic Effects and the Chemistry of the Heavier Main Group Elements. Relativistic Methods for Chemists. Challenges and Advances in Computational Chemistry and Physics 10. 2010: 78. ISBN 978-1-4020-9974-8. doi:10.1007/978-1-4020-9975-5_2.
^U(II)已在[K(2.2.2-Cryptand)][(C5H4SiMe3)3U]中觀察到,參見:MacDonald, Matthew R.; Fieser, Megan E.; Bates, Jefferson E.; Ziller, Joseph W.; Furche, Filipp; Evans, William J. Identification of the +2 Oxidation State for Uranium in a Crystalline Molecular Complex, [K(2.2.2-Cryptand)][(C5H4SiMe3)3U]. J. Am. Chem. Soc. 2013, 135 (36): 13310–13313. PMID 23984753. doi:10.1021/ja406791t.
^Pu(II)已在{Pu[C5H3(SiMe3)2]3}−中觀察到,參見:Windorff, Cory J.; Chen, Guo P; Cross, Justin N; Evans, William J.; Furche, Filipp; Gaunt, Andrew J.; Janicke, Michael T.; Kozimor, Stosh A.; Scott, Brian L. Identification of the Formal +2 Oxidation State of Plutonium: Synthesis and Characterization ofref name="curium5" {PuII[C5H3(SiMe3)2]3}−. J. Am. Chem. Soc. 2017, 139 (11): 3970–3973. PMID 28235179. doi:10.1021/jacs.7b00706.
^Pu(VIII)已在PuO 4中觀察到,參見:Nikonov, M. V.; Kiselev, Yu. M.; Tananaev, I. G.; Myasoedov, B. F. Plutonium volatility in ozonization of alkaline solutions of Pu(VI) hydroxo complexes. Doklady Chemistry. March 2011, 437 (1): 69–71. S2CID 95951175. doi:10.1134/S0012500811030104.,以及 Kiselev, Yu. M.; Nikonov, M. V.; Dolzhenko, V. D.; Ermilov, A. Yu.; Tananaev, I. G.; Myasoedov, B. F. On existence and properties of plutonium(VIII) derivatives. Radiochimica Acta. 17 January 2014, 102 (3): 227–237. S2CID 100915090. doi:10.1515/ract-2014-2146.
^Am(VII)已在AmO− 5中觀察到,參見:Americium (页面存档备份,存于互联网档案馆), 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, N. N.; Earnshaw, A. Chemistry of the Elements 2nd. Oxford:Butterworth-Heinemann. 1997: 1265. ISBN 0-7506-3365-4.
^ 137.0137.1137.2Kovács, Attila; Dau, Phuong D.; Marçalo, Joaquim; Gibson, John K. Pentavalent Curium, Berkelium, and Californium in Nitrate Complexes: Extending Actinide Chemistry and Oxidation States. Inorg. Chem. (American Chemical Society). 2018, 57 (15): 9453–9467. OSTI 1631597. PMID 30040397. S2CID 51717837. doi:10.1021/acs.inorgchem.8b01450.
^Cm(VI)已在三氧化鋦(CmO3)及二氧化鋦(2+)離子(CmO+ 2)中觀察到,參見:Domanov, V. P.; Lobanov, Yu. V. Formation of volatile curium(VI) trioxide CmO3. Radiochemistry. October 2011, 53 (5): 453–6. S2CID 98052484. doi:10.1134/S1066362211050018.
^Cm(VIII)曾被報告可能存在於四氧化鋦(CmO4)中,參閱:Domanov, V. P. Possibility of generation of octavalent curium in the gas phase in the form of volatile tetraoxide CmO4. Radiochemistry. January 2013, 55 (1): 46–51. S2CID 98076989. doi:10.1134/S1066362213010098.然而,後續的實驗顯示該物質似乎不存在:Zaitsevskii, Andréi; Schwarz, W H Eugen. Structures and stability of AnO4 isomers, An = Pu, Am, and Cm: a relativistic density functional study. Physical Chemistry Chemical Physics. April 2014, 2014 (16): 8997–9001. Bibcode:2014PCCP...16.8997Z. PMID 24695756. doi:10.1039/c4cp00235k.
^Sullivan, Jim C.; Schmidt, K. H.; Morss, L. R.; Pippin, C. G.; Williams, C. Pulse radiolysis studies of berkelium(III): preparation and identification of berkelium(II) in aqueous perchlorate media. Inorganic Chemistry. 1988, 27 (4): 597. doi:10.1021/ic00277a005.