Išči

    Oksidacijsko stanje

    Oksidacijsko stanje je v kemiji indikator stopnje oksidacije atoma ali kemijske spojine. Formalno oksidacijsko stanje je hipotetični naboj, ki bi ga imel atom, če bi bile vse njegove vezi z drugimi atomi 100 % ionske. Oksidacijska stanja so izražena s pozitivnimi ali negativnimi celimi števili ali z ničlo (0).

    Naraščanje oksidacijskega stanja med kemijsko reakcijo imenujemo oksidacija, padanje oksidacijskega stanja pa redukcijo. V takšnih reakcijah pride do prenosa elektronov: sprejemanje elektronov je redukcija, oddajanje elektronov pa oksidacija. Elementi imajo oksidacijsko število nič (0).

    Definicija oksidacijskega stanja po pravilih IUPAC:[1]

    "Oksidacijsko stanje: merilo stopnje oksidacije atoma ali spojine. Oksidacijsko stanje je definirano kot naboj, ki bi ga imel atom, če bi elektrone šteli po naslednjih pravilih: (1) oksidacijsko stanje prostega (nevezanega) elementa je enako nič; (2) oksidacijsko stanje enostavnega (enoatomskega) iona je enako neto naboju tega iona; (3) vodik in kisik imata v večini spojin oksidacijski stanji +1 (vodik) oziroma -2 (kisik); izjeme so kovinski hidridi, na primer LiH, v katerem ima vodik oksidacijsko stanje -1, in peroksidi, na primer H2O2, v katerih ima kisik oksidacijsko stanje -1; (4) algebraična vsota oksidacijskih stanj vseh atomov v nevtralni molekuli je enaka nič (0); algebraična vsota nabojev vseh atomov v ionu je enaka naboju iona. Primeri: oksidacijska stanja žvepla v spojinah H2S, S8 (elementarno žveplo), SO2, SO3 in H2SO4 so -2, 0, +4, +6 in +6. Višje oksidacijsko stanje nekega atoma pomeni višjo stopnjo oksidacije, nižje oksidacijsko stanje pa pomeni višjo stopnjo redukcije."

    Vsebina

    Računanje formalnega oksidacijskega stanja

    Oksidacijsko stanje atoma ali spojine lahko izračunamo na dva načina. Prvi način se uporablja za molekule, ki so prikazane z Lewisovo (strukturno) formulo, ki se pogosto uporablja za zapis organskih spojin. Drugi način se uporablja za preproste spojine, ki ne potrebujejo strukturne formule.

    Ponovno je treba poudariti, da oksidacijsko stanje atoma ne predstavlja njegovega realnega naboja, kar je še posebno res pri visokih oksidacijskih stanjih. Ionizacijska energija, ki je potrebna za tvorbo multiplega pozitivnega iona je namreč mnogo večja od energije, ki je na razpolago v kemijskih reakcijah. Pripisovanje elektronov posameznim atomom pri računanju oksidacijskega stanja je čisti formalizem, ki pa je zelo uporaben za razumevanje mnogih kemijskih reakcij.

    Računanje oksidacijskega stanja iz strukturne formule

    Za molekule z znano strukturno formulo lahko oksidacijska stanja atomov izračunamo z računanjem razlike med številom valenčnih elektronov, ki bi jih imel nevtralen atom elementa in številom elektronov, ki mu »pripadajo« v Lewisovi strukturi. Pri računanju oksidacijskega stanja upoštevamo naslednje zakonitosti: (1) vezni elektroni med atomi različnih elementov pripadejo bolj elektronegativnemu atomu, (2) vezne elektrone med dvema enakima atomoma si atoma razdelita in (3) elektroni iz neveznih elektronskih parov pripadajo tistemu elementu, ki jim ima.

    Primer: etanojska (ocetna) kislina

    Acetic acid structures4.png

    V metilni skupini (-CH3) ima ogljikov atom 6 valenčnih elektronov iz vezi s tremi vodikovimi atomi, ker je bolj elektronegativen od vodika, en elektron pa mu pripada iz elektronskega para vezi C-C. Ogljik ima torej 7 valenčnih elektronov. Nevtralni ogljikov atom bi imel 4 valenčne elektrone, ker je v 4. (oziroma 14.) skupini periodnega sistema elementov. Razlika 4 - 7 = -3 je oksidacijsko stanje tega ogljikovega atoma. Izračun seveda sloni na predpostavki, da so vse vezi 100 % ionske, kar seveda ni res. Ogljikov »ion« bi tem primeru zapisali kot C3-.

    Če na enak način izračunamo oskidacijsko stanje ogljikovega atoma v karboksilni skupini (-COOH), dobimo rezultat +3, ker mu pripada en elektron iz vezi C-C, ostali vezni elektroni pa pripadejo bolj elektronegativnemu kisiku. Oba kisikova atoma imata oksidacijsko stanje -2, ker imata po 8 elektronov: 4 iz vezi z ogljikom oziroma ogljikom in vodikom (ker sta bolj elektro negativna) in 4 svoje nevezne elektrone, nevtralni kisik pa bi jih imel 6. Vodik ima oksidacijsko število vedno enako +1, ker so vsi elementi, s katerimi se veže, bolj elektronegativni od njega samega.

    Oksidacijska stanja so zelo uporabna pri uravnovešanju redoks reakcij, v katerih mora biti število prejetih in oddanih elektronov enako. Če vzamemo za primer oksidacijo etanala (acetaldehida) s Tollensovim reagentom v etanojsko (ocetno) kislino, vidimo, da je karbonilni C atom spremenil svoje oksidacijsko stanje iz +1 v +3 (oksidacija). Na ta račun sta se dva atoma Ag reducirala iz Ag+ v Ag0:

    Change in oxidation state in Tollens reaction

    Računanje brez strukturne formule

    Algebaična vsota oksidacijskih stanj vseh atomov v nevtralni molekuli mora biti enaka nič, algebraična vsota oksidacijskih stanj v ionu pa mora biti enaka naboju iona. To dejstvo in dejstvo, da imajo nekateri elementi skoraj vedno določena oksidacijska stanja, omogočajo enostaven izračun oksidacijskih stanj atomov v enostavnih spojinah. Za izračunavanje upoštevamo naslednjih nekaj pravil:

    Primer: v spojini Cr(OH)3 ima kisik oksidacijsko stanje -2 (v spojini ni niti fluora niti vezi O-O), vodik pa +1 (vezan na elektronegativni kisik). Tri hidroksidne skupine imajo skupaj naboj 3x(-2+1) = -3, torej ima krom oksdacijsko stanje +3.

    Elementi z več oksidacijskimi stanji

    Večina elementov ima več kot eno oksidacijsko stanje. Ogljik ima devet oksidacijskih stanj:

    1. –4: CH4

    2. –3: C2H6

    3. –2: CH3F

    4. –1: C2H2

    5. 0: CH2F2

    6. +1: C2H2F4

    7. +2: CHF3

    8. +3: C2F6

    9. +4: CF4

    Kisik ima osem oksidacijskih stanj:

    1. -2: v večini oksidov, na primer ZnO, CO2, H2O

    2. -1: v vseh peroksidih

    3. : v superoksidih, na primer v KO2

    4. -⅓: v ozonidih, na primer RbO3

    5. 0: O2

    6. : kot dioksigenil, na primer v O2+[AsF6]-

    7. +1: O2F2

    8. +2: OF2

    Ulomljena oksidacijska stanja

    Formalna oksidacijska stanja atomov v Lewisovi zgradbi bi morala biti vedno cela števila. Osidacijska stanja se kljub temu pogosto izražajo z ulomki, ki predstavljajo povprečno oksidacijsko stanje atomov in drugih struktur. Primer: v KO2 ima kisik povprečno oksidacijsko stanje -½, ker ima en kisikov atom stanje 0, drugi pa -1. V nekaterih primerih sta zaradi resonance oba atoma lahko enakovredna. V takih primerih enostavna Lewisova strukturna formula ni uporabna, ker je za tak prikaz potrebnih več struktur.

    Oksidacijsko število

    Izraza osidacijsko stanje in oksidacijsko število sta pogosto zamenjljiva, če pa smo zelo natančni, se oksidacijsko število uporablja v kemiji kompleksnih (koordinacijskih) spojin in ima rahlo drugačen pomen. V kemiji kompleksov so namreč pravila za štetje elektronov drugačna: vsak elektron pripada ligandu skladno z njegovo elektronegativnostjo. Oksidacijska števila so običajno zapisana z rimskimi številkami, medtem ko so oksidacijska stanja zapisana z arabskimi številkami.

    Seznam oksidacijskih stanj elementov

    To je seznam znanih oksidacijskih stanje elementov, brez ulomljenih oksidacijskih stanj. Najpogostejše stanje je zapisano poudarjeno. Tabela temelji na Greenwood in Earnshaw,[2] z dodanimi komentarji. Vsak element obstaja v oksidacijskem stanju 0, medtem ko je čisti neioniziran element v katerikoli fazi. Stolpec oksidacijskega stanja 0 prikazuje le elemente za katere je znano da v spojinah obstajajo v oksidacijskem stanju 0.

      Žlahtni plin
    +1 Poudarjene vrednosti so glavna oksidacijska stanja
    Element Negativna stanja Pozitivna stanja Skupina Opombe
    −5 −4 −3 −2 −1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9
    Z
    1 vodik H −1 +1 1
    2 helij He 18
    3 litij Li +1 1 [3]
    4 berilij Be 0 +1 +2 2 [4][5]
    5 bor B −5 −1 0 +1 +2 +3 13 [6][7][8]
    6 ogljik C −4 −3 −2 −1 0 +1 +2 +3 +4 14
    7 dušik N −3 −2 −1 +1 +2 +3 +4 +5 15
    8 kisik O −2 −1 0 +1 +2 16
    9 fluor F −1 17
    10 neon Ne 18
    11 natrij Na −1 +1 1 [3]
    12 magnezij Mg +1 +2 2 [9]
    13 aluminij Al −2 −1 +1 +2 +3 13 [10][11][12]
    14 silicij Si −4 −3 −2 −1 0 +1 +2 +3 +4 14 [13]
    15 fosfor P −3 −2 −1 0 +1 +2 +3 +4 +5 15 [14]
    16 žveplo S −2 −1 0 +1 +2 +3 +4 +5 +6 16
    17 klor Cl −1 +1 +2 +3 +4 +5 +6 +7 17 [15]
    18 argon Ar 0 18 [16]
    19 kalij K −1 +1 1 [3]
    20 kalcij Ca +1 +2 2 [17]
    21 skandij Sc 0 +1 +2 +3 3 [18][19][20]
    22 titan Ti −2 −1 0 +1 +2 +3 +4 4 [21][22][23][24]
    23 vanadij V −3 −1 0 +1 +2 +3 +4 +5 5 [22]
    24 krom Cr −4 −2 −1 0 +1 +2 +3 +4 +5 +6 6 [22]
    25 mangan Mn −3 −2 −1 0 +1 +2 +3 +4 +5 +6 +7 7
    26 železo Fe −4 −2 −1 0 +1 +2 +3 +4 +5 +6 +7 8 [25][26][27]
    27 kobalt Co −3 −1 0 +1 +2 +3 +4 +5 9 [22]
    28 nikelj Ni −2 −1 0 +1 +2 +3 +4 10 [28]
    29 baker Cu −2 0 +1 +2 +3 +4 11 [27][29]
    30 cink Zn −2 0 +1 +2 12 [27][30][31]
    31 galij Ga −5 −4 −3 −2 −1 +1 +2 +3 13 [11][32][33]
    32 germanij Ge −4 −3 −2 −1 0 +1 +2 +3 +4 14 [34][13]
    33 arzen As −3 −2 −1 0 +1 +2 +3 +4 +5 15 [11][35][36][37]
    34 selen Se −2 −1 +1 +2 +3 +4 +5 +6 16 [38][39][40][41]
    35 brom Br −1 +1 +3 +4 +5 +7 17
    36 kripton Kr 0 +1 +2 18
    37 rubidij Rb −1 +1 1 [3]
    38 stroncij Sr +1 +2 2 [42]
    39 itrij Y 0 +1 +2 +3 3 [43][44][45]
    40 cirkonij Zr −2 0 +1 +2 +3 +4 4 [22][46][47]
    41 niobij Nb −3 −1 0 +1 +2 +3 +4 +5 5 [22][48][49]
    42 molibden Mo −4 −2 −1 0 +1 +2 +3 +4 +5 +6 6 [22]
    43 tehnecij Tc −3 −1 0 +1 +2 +3 +4 +5 +6 +7 7
    44 rutenij Ru −4 −2 0 +1 +2 +3 +4 +5 +6 +7 +8 8 [22][27]
    45 rodij Rh −3 −1 0 +1 +2 +3 +4 +5 +6 9 [22][50]
    46 paladij Pd 0 +1 +2 +3 +4 10 [51][52]
    47 srebro Ag −2 −1 +1 +2 +3 11 [27][53]
    48 kadmij Cd −2 +1 +2 12 [27][54]
    49 indij In −5 −2 −1 +1 +2 +3 13 [11][55][56]
    50 kositer Sn −4 −3 −2 −1 0 +1 +2 +3 +4 14 [11][57][58][13]
    51 antimon Sb −3 −2 −1 0 +1 +2 +3 +4 +5 15 [11][59][60][61][62]
    52 telur Te −2 −1 +1 +2 +3 +4 +5 +6 16 [11][63][64][65]
    53 jod I −1 +1 +3 +4 +5 +6 +7 17 [66][67]
    54 ksenon Xe 0 +1 +2 +4 +6 +8 18 [68][69][70]
    55 cezij Cs −1 +1 1 [3]
    56 barij Ba +1 +2 2 [71]
    57 lantan La 0 +1 +2 +3 n/a [43][72]
    58 cerij Ce +2 +3 +4 n/a
    59 praseodim Pr 0 +1 +2 +3 +4 +5 n/a [43][73][74][75]
    60 neodim Nd 0 +2 +3 +4 n/a [43][76]
    61 prometij Pm +2 +3 n/a [77]
    62 samarij Sm 0 +2 +3 n/a [43]
    63 evropij Eu 0 +2 +3 n/a [43]
    64 gadolinij Gd 0 +1 +2 +3 n/a [43]
    65 terbij Tb 0 +1 +2 +3 +4 n/a [43][77]
    66 disprozij Dy 0 +2 +3 +4 n/a [43][78]
    67 holmij Ho 0 +2 +3 n/a [43][77]
    68 erbij Er 0 +2 +3 n/a [43][77]
    69 tulij Tm 0 +2 +3 n/a [43]
    70 iterbij Yb 0 +2 +3 n/a [43]
    71 lutecij Lu 0 +2 +3 3 [43][77]
    72 hafnij Hf −2 0 +1 +2 +3 +4 4 [22][47][79]
    73 tantal Ta −3 −1 0 +1 +2 +3 +4 +5 5 [22][49]
    74 volfram W −4 −2 −1 0 +1 +2 +3 +4 +5 +6 6 [22]
    75 renij Re −3 −1 0 +1 +2 +3 +4 +5 +6 +7 7
    76 osmij Os −4 −2 −1 0 +1 +2 +3 +4 +5 +6 +7 +8 8 [27][80]
    77 iridij Ir −3 −1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 9 [81][82][83][84]
    78 platina Pt −3 −2 −1 0 +1 +2 +3 +4 +5 +6 10 [27][85][86]
    79 zlato Au −3 −2 −1 0 +1 +2 +3 +5 11 [27][87]
    80 živo srebro Hg −2 +1 +2 12 [27][88]
    81 talij Tl −5 −2 −1 +1 +2 +3 13 [11][89][90][91]
    82 svinec Pb −4 −2 −1 +1 +2 +3 +4 14 [11][92][93]
    83 bizmut Bi −3 −2 −1 +1 +2 +3 +4 +5 15 [94][95][96][97]
    84 polonij Po −2 +2 +4 +5 +6 16 [98]
    85 astat At −1 +1 +3 +5 +7 17
    86 radon Rn +2 +6 18 [99][100][101]
    87 francij Fr +1 1
    88 radij Ra +2 2
    89 aktinij Ac +3 n/a
    90 torij Th +1 +2 +3 +4 n/a [102][103]
    91 protaktinij Pa +3 +4 +5 n/a
    92 uran U +1 +2 +3 +4 +5 +6 n/a [104][105]
    93 neptunij Np +2 +3 +4 +5 +6 +7 n/a [106]
    94 plutonij Pu +2 +3 +4 +5 +6 +7 +8 n/a [107][108]
    95 americij Am +2 +3 +4 +5 +6 +7 n/a [109]
    96 kirij Cm +3 +4 +5 +6 n/a [110][111][112][113]
    97 berkelij Bk +2 +3 +4 +5 n/a [110][111][114][115][116]
    98 kalifornij Cf +2 +3 +4 +5 n/a [110][111]
    99 ajnštajnij Es +2 +3 +4 n/a [117]
    100 fermij Fm +2 +3 n/a
    101 mendelevij Md +2 +3 n/a
    102 nobelij No +2 +3 n/a
    103 lavrencij Lr +3 3
    104 raderfordij Rf +4 4
    105 dubnij Db +5 5 [118]
    106 siborgij Sg 0 +6 6 [119][120]
    107 borij Bh +7 7 [121]
    108 hasij Hs +8 8 [122]
    109 majtnerij Mt 9
    110 darmštatij Ds 10
    111 rentgenij Rg 11
    112 kopernicij Cn +2 12 [123]
    113 nihonij Nh 13
    114 flerovij Fl 14
    115 moskovij Mc 15
    116 livermorij Lv 16
    117 tenes Ts 17
    118 oganeson Og 18

    Zgodovina

    Koncept oksidacijskih stanj, kot ga poznamo danes, je vpeljal W.M. Latimer leta 1938. Oksidacijo kot tako je prvi študiral Antoine Lavoisier (1743–1794), ki je nanjo gledal kot na reakcijo elementov s kisikom in je bil prepričan, da kemijske vezi v vseh soleh temeljijo na kisiku.[124]

    Viri

    Sklici

    1. IUPAC Gold Book
    2. Predloga:Greenwood&Earnshaw
    3. 3,0 3,1 3,2 3,3 3,4 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.
    4. Be(0) has been observed; see "Beryllium(0) Complex Found". Chemistry Europe. 13 June 2016.
    5. Be(I) has been observed in beryllium monohydride (BeH); see Shayesteh, A.; Tereszchuk, K.; Bernath, P. F.; Colin, R. (2003). "Infrared Emission Spectra of BeH and BeD" (PDF). J. Chem. Phys. 118 (3): 1158. Bibcode:2003JChPh.118.1158S. doi:10.1063/1.1528606. Arhivirano iz prvotnega spletišča (PDF) dne 2007-12-02. Pridobljeno dne 2007-12-10. and in [(CAAC)2Be]+• [CAAC = cyclic (alkyl)(amino)carbene], see Wang, Guocang; Walley, Jacob E.; Dickie, Diane E.; Pan, Sudip; Frenking, Gernot; Gilliard Jr., Robert G. (2020). "A Stable, Crystalline Beryllium Radical Cation". J. Am. Chem. Soc. 142 (10): 4560–4. doi:10.1021/jacs.9b13777. Pridobljeno dne 2020-11-17.
    6. B(−5) has been observed in Al3BC, see Schroeder, Melanie. "Eigenschaften von borreichen Boriden und Scandium-Aluminium-Oxid-Carbiden" (nemščina). str. 139.
    7. B(−1) has been observed in magnesium diboride (MgB2), see Keeler, James; Wothers, Peter (2014). Chemical Structure and Reactivity: An Integrated Approach. Oxford University Press. ISBN 9780199604135.
    8. B(0) has been observed in diborynes, see Braunschweig, H.; Dewhurst, R. D.; Hammond, K.; Mies, J.; Radacki, K.; Vargas, A. (2012). "Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond". Science. 336 (6087): 1420–2. Bibcode:2012Sci...336.1420B. doi:10.1126/science.1221138. PMID 22700924.
    9. Low valent magnesium compounds with Mg(I) have been obtained using bulky ligands; see Green, S. P.; Jones C.; Stasch A. (December 2007). "Stable Magnesium(I) Compounds with Mg-Mg Bonds". Science. 318 (5857): 1754–1757. Bibcode:2007Sci...318.1754G. doi:10.1126/science.1150856. PMID 17991827.
    10. Al(II) has been observed in aluminium(II) oxide (AlO); see Tyte, D.C. (1964). "Red (B2Π–A2σ) Band System of Aluminium Monoxide". Nature. 202 (4930): 383–384. Bibcode:1964Natur.202..383T. doi:10.1038/202383a0, and in dialanes (R2Al—AlR2); see Uhl, Werner (2004). "Organoelement Compounds Possessing Al—Al, Ga—Ga, In—In, and Tl—Tl Single Bonds". Advances in Organometallic Chemistry. 51: 53–108. doi:10.1016/S0065-3055(03)51002-4.
    11. 11,0 11,1 11,2 11,3 11,4 11,5 11,6 11,7 11,8 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 phases, see: Riedel, Erwin, ur. (2007). Moderne Anorganische Chemie (nemščina). str. 259, and "Vorlesung Intermetallische Phasen § 6.2 Binäre Zintl-Phasen" (nemščina).
    12. Al(−2) has been observed in Sr14[Al4]2[Ge]3, see Wemdorff, Marco; Röhr, Caroline (2007). "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 (nemščina). 62 (10): 1227. doi:10.1515/znb-2007-1001.
    13. 13,0 13,1 13,2 "New Type of Zero-Valent Tin Compound". Chemistry Europe. 27 August 2016.
    14. P(0) has been observed, see Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; King, R. Bruce; Schaefer, Iii; Schleyer, Paul v. R.; Robinson, Gregory H. (2008). "Carbene-Stabilized Diphosphorus". Journal of the American Chemical Society. 130 (45): 14970–1. doi:10.1021/ja807828t. PMID 18937460.
    15. The equilibrium Cl2O6⇌2ClO3 is mentioned by Greenwood and Earnshaw, but it has been refuted, see Lopez, Maria; Juan E. Sicre (1990). "Physicochemical properties of chlorine oxides. 1. Composition, ultraviolet spectrum, and kinetics of the thermolysis of gaseous dichlorine hexoxide". J. Phys. Chem. 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 (1994). "Chlorine Trioxide: Spectroscopic Properties, Molecular Structure, and Photochemical Behavior". Angew. Chem. Int. Ed. 33 (14): 1482–1484. doi:10.1002/anie.199414821.
    16. Ar(0) has been observed in argon fluorohydride (HArF) and ArCF22+, see Lockyear, J.F.; Douglas, K.; Price, S.D.; Karwowska, M.; et al. (2010). "Generation of the ArCF22+ Dication". Journal of Physical Chemistry Letters. 1: 358. doi:10.1021/jz900274p. Neznan parameter |name-list-style= ni upoštevan (pomoč)
    17. Ca(I) has been observed; see Krieck, Sven; Görls, Helmar; Westerhausen, Matthias (2010). "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. 132 (35): 12492–501. doi:10.1021/ja105534w. PMID 20718434.
    18. Sc(0) has been observed; see F. Geoffrey N. Cloke; Karl Khan; Robin N. Perutz (1991). "η-Arene complexes of scandium(0) and scandium(II)". J. Chem. Soc., Chem. Commun. (19): 1372–1373. doi:10.1039/C39910001372. Neznan parameter |name-list-style= ni upoštevan (pomoč)
    19. Sc(I) has been observed; see Polly L. Arnold; F. Geoffrey; N. Cloke; Peter B. Hitchcock; John F. Nixon (1996). "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. 118 (32): 7630–7631. doi:10.1021/ja961253o. Neznan parameter |name-list-style= ni upoštevan (pomoč)
    20. Sc(II) has been observed; see Woen, David H.; Chen, Guo P.; Ziller, Joseph W.; Boyle, Timothy J.; Furche, Filipp; Evans, William J. (January 2017). "Solution Synthesis, Structure, and CO Reduction Reactivity of a Scandium(II) Complex". Angewandte Chemie International Edition. 56 (8): 2050–2053. doi:10.1002/anie.201611758. PMID 28097771.
    21. Ti(I) has been observed in [Ti(η6-1,3,5-C6H3iPr3)2][BAr4] (Ar = C6H5, p-C6H4F, 3,5-C6H3(CF3)2); see Calderazzo, Fausto; Ferri, Isabella; Pampaloni, Guido; Englert, Ulli; Green, Malcolm L. H. (1997). "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. 16 (14): 3100–3101. doi:10.1021/om970155o.
    22. 22,00 22,01 22,02 22,03 22,04 22,05 22,06 22,07 22,08 22,09 22,10 22,11 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 [1], p. 4 (in German); [2], pp. 97–100; [3], p. 239
    23. Ti(−1) has been reported in [Ti(bipy)3], but was later shown to be Ti(+3); see Bowman, A. C.; England, J.; Sprouls, S.; Weihemüller, T.; Wieghardt, K. (2013). "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. 52 (4): 2242–56. doi:10.1021/ic302799s. PMID 23387926. However, Ti(−1) occurs in [Ti(η-C6H6] and [Ti(η-C6H5CH3)], see Bandy, J. A.; Berry, A.; Green, M. L. H.; Perutz, R. N.; Prout, K.; Verpeautz, J.-N. (1984). "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. 52 (4): 729–731. doi:10.1039/C39840000729.
    24. Jilek, Robert E.; Tripepi, Giovanna; Urnezius, Eugenijus; Brennessel, William W.; Young, Victor G. Jr.; Ellis, John E. (2007). "Zerovalent titanium–sulfur complexes. Novel dithiocarbamato derivatives of Ti(CO)6: [Ti(CO)4(S2CNR2)]". Chem. Commun. (25): 2639–2641. doi:10.1039/B700808B. PMID 17579764.
    25. Fe(VII) has been observed in [FeO4]; see Lu, Jun-Bo; Jian, Jiwen; Huang, Wei; Lin, Hailu; Zhou, Mingfei (2016). "Experimental and theoretical identification of the Fe(VII) oxidation state in FeO4". Physical Chemistry Chemical Physics. 18 (45): 31125–31131. Bibcode:2016PCCP...1831125L. doi:10.1039/C6CP06753K. PMID 27812577.
    26. Fe(VIII) has been reported; see Yurii D. Perfiliev; Virender K. Sharma (2008). "Higher Oxidation States of Iron in Solid State: Synthesis and Their Mössbauer Characterization – Ferrates – ACS Symposium Series (ACS Publications)". Platinum Metals Review. 48 (4): 157–158. doi:10.1595/147106704X10801. However, its existence has been disputed.
    27. 27,0 27,1 27,2 27,3 27,4 27,5 27,6 27,7 27,8 27,9 Fe(−4), Ru(−4), and Os(−4) have been observed in metal-rich compounds containing octahedral complexes [MIn6−xSnx]; Pt(−3) (as a dimeric anion [Pt–Pt]6−), 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]2− for Zn, Cd, Hg, but later shown to be [T–T]4− for all these elements) in La2Pt2In, La2Cu2In, Ca5Au3, Ca5Ag3, Ca5Hg3, Sr5Cd3, Ca5Zn3(structure (AE2+)5(T–T)4−T2−⋅4e), Yb3Ag2, Ca5Au4, and Ca3Hg2; Au(–3) has been observed in ScAuSn and in other 18-electron half-Heusler compounds. See Changhoon Lee; Myung-Hwan Whangbo (2008). "Late transition metal anions acting as p-metal elements". Solid State Sciences. 10 (4): 444–449. Bibcode:2008SSSci..10..444K. doi:10.1016/j.solidstatesciences.2007.12.001. and Changhoon Lee; Myung-Hwan Whangbo; Jürgen Köhler (2010). "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. 636 (1): 36–40. doi:10.1002/zaac.200900421.
    28. Ni(−2) has been observed in Li2[Ni(1,5-COD)2], see Jonas, Klaus (1975). "Dilithium-Nickel-Olefin Complexes. Novel Bimetal Complexes Containing a Transition Metal and a Main Group Metal". Angew. Chem. Int. Ed. 14 (11): 752–753. doi:10.1002/anie.197507521. and Ellis, John E. (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–86. doi:10.1021/ic052110i. PMID 16602773.
    29. Cu(0) has been observed in Cu(tris[2-(diisopropylphosphino)- phenyl]borane), see Moret, Marc-Etienne; Zhang, Limei; Peters, Jonas C. (2013). "A Polar Copper–Boron One-Electron σ-Bond". J. Am. Chem. Soc. 135 (10): 3792–3795. doi:10.1021/ja4006578. PMID 23418750.
    30. Zn(0) has been observed; see Singh, Amit Pratap; Samuel, Prinson P.; Roesky, Herbert W.; Schwarzer, Martin C.; Frenking, Gernot; Sidhu, Navdeep S.; Dittrich, Birger (2013). "A Singlet Biradicaloid Zinc Compound and Its Nonradical Counterpart". J. Am. Chem. Soc. 135 (19): 7324–9. doi:10.1021/ja402351x. and Soleilhavoup, Michèle; Bertrand, Guy (2015). "Cyclic (Alkyl)(Amino)Carbenes (CAACs): Stable Carbenes on the Rise". Acc. Chem. Res. 48 (2): 256–266. doi:10.1021/ar5003494.
    31. Zn(I) has been observed in decamethyldizincocene (Zn25–C5Me5)2); see Resa, I.; Carmona, E.; Gutierrez-Puebla, E.; Monge, A. (2004). "Decamethyldizincocene, a Stable Compound of Zn(I) with a Zn-Zn Bond". Science. 305 (5687): 1136–8. Bibcode:2004Sci...305.1136R. doi:10.1126/science.1101356. PMID 15326350.
    32. Ga(−2), Ga(−4), and Ga(−5) have been observed in the magnesium gallides MgGa, Mg2Ga, and Mg5Ga2, respectively; see Patrick Hofmann. "Colture. Ein Programm zur interaktiven Visualisierung von Festkörperstrukturen sowie Synthese, Struktur und Eigenschaften von binären und ternären Alkali- und Erdalkalimetallgalliden" (PDF) (nemščina). str. 72.
    33. Ga(−3) has been observed in LaGa, see Dürr, Ines; Bauer, Britta; Röhr, Caroline (2011). "Lanthan-Triel/Tetrel-ide La(Al,Ga)x(Si,Ge)1-x. Experimentelle und theoretische Studien zur Stabilität intermetallischer 1:1-Phasen" (PDF). Z. Naturforsch. (nemščina). 66b: 1107–1121.
    34. Ge(−1), Ge(−2), and Ge(−3) have been observed in germanides; see Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1995). "Germanium". Lehrbuch der Anorganischen Chemie (nemščina) (101 izd.). Walter de Gruyter. str. 953–959. ISBN 978-3-11-012641-9.
    35. As(0) has been observed; see Abraham, Mariham Y.; Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; Shaefer III, Henry F.; Schleyer, P. von R.; Robinson, Gregory H. (2010). "Carbene Stabilization of Diarsenic: From Hypervalency to Allotropy". Chemistry: a European Journal. 16 (2): 432–5. doi:10.1002/chem.200902840.
    36. As(I) has been observed in arsenic(I) iodide (AsI); see Ellis, Bobby D.; MacDonald, Charles L. B. (2004). "Stabilized Arsenic(I) Iodide: A Ready Source of Arsenic Iodide Fragments and a Useful Reagent for the Generation of Clusters". Inorganic Chemistry. 43 (19): 5981–6. doi:10.1021/ic049281s. PMID 15360247.
    37. As(IV) has been observed in arsenic(IV) hydroxide (As(OH)4) and HAsO-; see Kläning, Ulrik K.; Bielski, Benon H. J.; Sehested, K. (1989). "Arsenic(IV). A pulse-radiolysis study". Inorganic Chemistry. 28 (14): 2717–24. doi:10.1021/ic00313a007.
    38. Se(−1) has been observed in diselenides(2−) (Se22−).
    39. Se(I) has been observed in selenium(I) chloride (Se2Cl2); see "Selenium: Selenium(I) chloride compound data". WebElements.com. Pridobljeno dne 2007-12-10.
    40. Se(III) has been observed in Se2NBr3; see Lau, Carsten; Neumüller, Bernhard; Vyboishchikov, Sergei F.; Frenking, Gernot; Dehnicke, Kurt; Hiller, Wolfgang; Herker, Martin (1996). "Se2NBr3, Se2NCl5, Se2NCl6: New Nitride Halides of Selenium(III) and Selenium(IV)". Chemistry: A European Journal. 2 (11): 1393–1396. doi:10.1002/chem.19960021108.
    41. Se(V) has been observed in SeO2- and HSeO2-; see Kläning, Ulrik K.; Sehested, K. (1986). "Selenium(V). A pulse radiolysis study". Inorganic Chemistry. 90 (21): 5460–4. doi:10.1021/j100412a112.
    42. Sr(I) has been observed in strontium monofluoride (SrF); see P. Colarusso; Guo, B.; Zhang, K.-Q.; Bernath, P.F.; et al. (1996). "High-Resolution Infrared Emission Spectrum of Strontium Monofluoride" (PDF). Journal of Molecular Spectroscopy. 175 (1): 158–171. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019. Arhivirano iz prvotnega spletišča (PDF) dne 2012-03-08.
    43. 43,00 43,01 43,02 43,03 43,04 43,05 43,06 43,07 43,08 43,09 43,10 43,11 43,12 43,13 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 Cloke, F. Geoffrey N. (1993). "Zero Oxidation State Compounds of Scandium, Yttrium, and the Lanthanides". Chem. Soc. Rev. 22: 17–24. doi:10.1039/CS9932200017. and Arnold, Polly L.; Petrukhina, Marina A.; Bochenkov, Vladimir E.; Shabatina, Tatyana I.; Zagorskii, Vyacheslav V.; Cloke (2003-12-15). "Arene complexation of Sm, Eu, Tm and Yb atoms: a variable temperature spectroscopic investigation". Journal of Organometallic Chemistry. 688 (1–2): 49–55. doi:10.1016/j.jorganchem.2003.08.028.
    44. Y(I) has been observed in yttrium(I) bromide (YBr); see "Yttrium: yttrium(I) bromide compound data". OpenMOPAC.net. Arhivirano iz prvotnega spletišča dne 2011-07-23. Pridobljeno dne 2007-12-10.
    45. Y(II) has been observed in [(18-crown-6)K][(C5H4SiMe3)3Y]; see MacDonald, M. R.; Ziller, J. W.; Evans, W. J. (2011). "Synthesis of a Crystalline Molecular Complex of Y2+, [(18-crown-6)K][(C5H4SiMe3)3Y]". J. Am. Chem. Soc. 133 (40): 15914–17. doi:10.1021/ja207151y. PMID 21919538.
    46. Zr(−1) has been reported in [Zr(bipy)3] (see Predloga:Greenwood&Earnshaw and Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1995). "Zirconium". Lehrbuch der Anorganischen Chemie (nemščina) (101 izd.). Walter de Gruyter. str. 1413. ISBN 978-3-11-012641-9.), but was later shown to be Zr(+4); see Bowman, A. C.; England, J.; Sprouls, S.; Weihemüller, T.; Wieghardt, K. (2013). "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. 52 (4): 2242–56. doi:10.1021/ic302799s. PMID 23387926.
    47. 47,0 47,1 Zr(0) and Hf(0) occur in (η6-(1,3,5-tBu)3C6H3)2M (M=Zr, Hf) and [(η5-C5R5M(CO)4], see Chirik, P. J.; Bradley, C. A. (2007). "4.06 - Complexes of Zirconium and Hafnium in Oxidation States 0 to ii". Comprehensive Organometallic Chemistry III. From Fundamentals to Applications. 4. Elsevier Ltd. str. 697–739. doi:10.1016/B0-08-045047-4/00062-5.
    48. Complexes of Nb(0) and Ta(0) have been observed, see Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (2003). "4.5.7. Niobium(0) and Tantalum(0)". V J. A. McCleverty; T.J. Meyer (ur.). Comprehensive Coordination Chemistry II: From Biology to Nanotechnology. 4 (2 izd.). Newnes. str. 297–299. ISBN 978-0-08-091316-2.
    49. 49,0 49,1 Nb(I) and Ta(I) occur in CpNb(CO)4 and CpTa(CO)4, see Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1995). "Tantal". Lehrbuch der Anorganischen Chemie (nemščina) (101 izd.). Walter de Gruyter. str. 1430. ISBN 978-3-11-012641-9. and King, R. Bruce (1969). Transition-Metal Organometallic Chemistry: An Introduction. Academic Press. str. 11. ISBN 978-0-32-315996-8.
    50. George, G.N.; Klein, S.I.; Nixon, J.F. (1984). "Electron paramagnetic resonance spectroscopic studies on the zero-valent rhodium complex [Rh(P(OPri)3)4] at X-and Q-band frequencies". Chemical Physics Letters. 108 (6): 627–630. Bibcode:1984CPL...108..627G. doi:10.1016/0009-2614(84)85069-1.
    51. Pd(I) has been observed; see Crabtree, R. H. (2002). "CHEMISTRY: A New Oxidation State for Pd?". Science. 295 (5553): 288–289. doi:10.1126/science.1067921. PMID 11786632.
    52. Pd(III) has been observed; see Powers, D. C.; Ritter, T. (2011). Palladium(III) in Synthesis and Catalysis (PDF). Top. Organomet. Chem. Topics in Organometallic Chemistry. 35. str. 129–156. Bibcode:2011hoso.book..129P. doi:10.1007/978-3-642-17429-2_6. ISBN 978-3-642-17428-5. PMC 3066514. PMID 21461129. Arhivirano iz prvotnega spletišča (PDF) dne June 12, 2013.
    53. The Ag ion has been observed in metal ammonia solutions: see Tran, N. E.; Lagowski, J. J. (2001). "Metal Ammonia Solutions: Solutions Containing Argentide Ions". Inorganic Chemistry. 40 (5): 1067–68. doi:10.1021/ic000333x.
    54. Cd(I) has been observed in cadmium(I) tetrachloroaluminate (Cd2(AlCl4)2); see Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). "Cadmium". Lehrbuch der Anorganischen Chemie (nemščina) (91–100 izd.). Walter de Gruyter. str. 1056–1057. ISBN 978-3-11-007511-3.
    55. In(–5) has been observed in La3InGe, see Guloy, A. M.; Corbett, J. D. (1996). "Synthesis, Structure, and Bonding of Two Lanthanum Indium Germanides with Novel Structures and Properties". Inorganic Chemistry. 35 (9): 2616–22. doi:10.1021/ic951378e.
    56. In(−2) has been observed in Na2In, see [4], p. 69.
    57. Sn(−3) has been observed in [Sn2]6−, e.g. in (Ba2)4+(Mg4)8+Sn4−(Sn2)6−Sn2− (with square (Sn2−)n sheets), see Papoian, Garegin A.; Hoffmann, Roald (2000). "Hypervalent Bonding in One, Two, and Three Dimensions: Extending the Zintl–Klemm Concept to Nonclassical Electron-Rich Networks". Angew. Chem. Int. Ed. 2000 (39): 2408–2448. doi:10.1002/1521-3773(20000717)39:14<2408::aid-anie2408>3.0.co;2-u. Pridobljeno dne 2015-02-23.
    58. Sn(I) and Sn(III) have been observed in organotin compounds
    59. Sb(−2) has been observed in [Sb2]4−, e.g. in RbBa4[Sb2][Sb][O], see Boss, Michael; Petri, Denis; Pickhard, Frank; Zönnchen, Peter; Röhr, Caroline (2005). "Neue Barium-Antimonid-Oxide mit den Zintl-Ionen [Sb]3−, [Sb2]4− und 1[Sbn]n− / New Barium Antimonide Oxides containing Zintl Ions [Sb]3−, [Sb2]4− and 1[Sbn]n−". Zeitschrift für Anorganische und Allgemeine Chemie (nemščina). 631 (6–7): 1181–1190. doi:10.1002/zaac.200400546.
    60. Sb(0) has been observed, see Anastas Sidiropoulos. "Studies of N-heterocyclic Carbene (NHC) Complexes of the Main Group Elements" (PDF). str. 39.
    61. Sb(I) and Sb(II) have been observed in organoantimony compounds; for Sb(I), see Šimon, Petr; de Proft, Frank; Jambor, Roman; Růžička, Aleš; Dostál, Libor (2010). "Monomeric Organoantimony(I) and Organobismuth(I) Compounds Stabilized by an NCN Chelating Ligand: Syntheses and Structures". Angewandte Chemie International Edition. 49 (32): 5468–5471. doi:10.1002/anie.201002209. PMID 20602393.
    62. Sb(IV) has been observed in [SbCl]2−, see Nobuyoshi Shinohara; Masaaki Ohsima (2000). "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. 73 (7): 1599–1604. doi:10.1246/bcsj.73.1599.
    63. Te(I) has been observed in tellurium iodide (TeI), see "Tellurium: tellurium iodide". WebElements.com. Pridobljeno dne 2015-02-23.
    64. Te(III) has been observed in [Te(N(SiMe3)2)2]+, see Heinze, Thorsten; Roesky, Herbert W.; Pauer, Frank; Stalke, Dietmar; Sheldrick, George M. (1991). "Synthesis and Structure of the First Tellurium(III) Radical Cation". Angewandte Chemie International Edition. 30 (12): 1678. doi:10.1002/anie.199116771. Pridobljeno dne 2015-02-23.
    65. 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 (Te2F10) is actually bis(pentafluorotelluryl) oxide, F5TeOTeF5: see Watkins, P. M. (1974). "Ditellurium decafluoride - A Continuing Myth". Journal of Chemical Education. 51 (9): 520–521. Bibcode:1974JChEd..51..520W. doi:10.1021/ed051p520. However, Te(V) has been observed in HTeO-, TeO-, HTeO2-, and TeO3-; see Kläning, Ulrik K.; Sehested, K. (2001). "Tellurium(V). A Pulse Radiolysis Study". The Journal of Physical Chemistry A. 105 (27): 6637–45. Bibcode:2001JPCA..105.6637K. doi:10.1021/jp010577i.
    66. I(IV) has been observed in iodine dioxide (IO2); see Pauling, Linus (1988). "Oxygen Compounds of Nonmetallic Elements". General Chemistry (3rd izd.). Dover Publications, Inc. str. 259. ISBN 978-0-486-65622-9.
    67. I(VI) has been observed in IO3, IO42−, H5IO6, H2IO52−, H4IO62−, and HIO53−; see Kläning, Ulrik K.; Sehested, Knud; Wolff, Thomas (1981). "Laser flash photolysis and pulse radiolysis of iodate and periodate in aqueous solution. Properties of iodine(VI)". J. Chem. Soc., Faraday Trans. 1. 77 (7): 1707–18. doi:10.1039/F19817701707.
    68. Xe compounds: see Xenon
    69. Xe(0) has been observed in tetraxenonogold(II) (AuXe42+).
    70. Xe(I) has been reported in xenon hexafluoroplatinate and xenon hexafluororhodate (see Pauling, Linus (1988). General Chemistry (3rd izd.). Dover Publications, Inc. str. 250. ISBN 978-0-486-65622-9.), however these compounds were later found to contain Xe(II).
    71. Ba(I) has been observed in barium monofluoride (BaF); see P. Colarusso; Guo, B.; Zhang, K.-Q.; Bernath, P.F.; et al. (1995). "High-Resolution Fourier Transform Infrared Emission Spectrum of Barium Monofluoride" (PDF). Journal of Molecular Spectroscopy. 170: 59. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019. Arhivirano iz prvotnega spletišča (PDF) dne 2005-03-10.
    72. La(I) has been observed in lanthanum monohydride (LaH); see Ram, R. S.; Bernath, P. F. (1996). "Fourier Transform Emission Spectroscopy of New Infrared Systems of LaH and LaD" (PDF). Journal of Molecular Spectroscopy. 104 (17): 6444. Bibcode:1996JChPh.104.6444R. doi:10.1063/1.471365. Arhivirano iz prvotnega spletišča (PDF) dne 2005-03-10.
    73. Pr(I) has been observed in [PrB4]; see Chen, Xin; Chen, Teng-Teng; Li, Wang-Lu; Lu, Jun-Bo; Zhao, Li-Juan; Jian, Tian; Hu, Han-Shi; Wang, Lai-Sheng; Li, Jun (2018-12-13). "Lanthanides with Unusually Low Oxidation States in the PrB3 and PrB4 Boride Clusters". Inorganic Chemistry. 58 (1): 411–418. doi:10.1021/acs.inorgchem.8b02572. PMID 30543295.
    74. Pr(V) has been observed in [PrO2]+; see Zhang, Qingnan; Hu, Shu-Xian; Qu, Hui; Su, Jing; Wang, Guanjun; Lu, Jun-Bo; Chen, Mohua; Zhou, Mingfei; Li, Jun (2016-06-06). "Pentavalent Lanthanide Compounds: Formation and Characterization of Praseodymium(V) Oxides". Angewandte Chemie International Edition. 55 (24): 6896–6900. doi:10.1002/anie.201602196. ISSN 1521-3773. PMID 27100273.
    75. Hu, Shu-Xian; Jian, Jiwen; Su, Jing; Wu, Xuan; Li, Jun; Zhou, Mingfei (2017). "Pentavalent lanthanide nitride-oxides: NPrO and NPrO− complexes with N≡Pr triple bonds". Chemical Science (angleščina). 8 (5): 4035–4043. doi:10.1039/C7SC00710H. ISSN 2041-6520. PMC 5434915. PMID 28580119.
    76. Nd(IV) has been observed in unstable solid state compounds; see Predloga:Holleman&Wiberg
    77. 77,0 77,1 77,2 77,3 77,4 All the lanthanides (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 Predloga:Holleman&Wiberg) and (except Pm) in organometallic molecular complexes, see Lanthanides Topple Assumptions and Meyer, G. (2014). "All the Lanthanides Do It and Even Uranium Does Oxidation State +2". Angewandte Chemie International Edition. 53 (14): 3550–51. doi:10.1002/anie.201311325. PMID 24616202.. Additionally, all the lanthanides (La–Lu) form dihydrides (LnH2), dicarbides (LnC2), monosulfides (LnS), monoselenides (LnSe), and monotellurides (LnTe), but for most elements these compounds have Ln3+ ions with electrons delocalized into conduction bands, e. g. Ln3+(H)2(e).
    78. Dy(IV) has been observed in unstable solid state compounds; see Predloga:Holleman&Wiberg
    79. Hf(I) has been observed in hafnium monobromide (HfBr), see Marek, G.S.; Troyanov, S.I.; Tsirel'nikov, V.I. (1979). "Кристаллическое строение и термодинамические характеристики монобромидов циркония и гафния / Crystal structure and thermodynamic characteristics of monobromides of zirconium and hafnium". Журнал неорганической химии / Russian Journal of Inorganic Chemistry (ruščina). 24 (4): 890–893.
    80. Os(−1) has been observed in Na[Os(CO)13]; see Krause, J.; Siriwardane, Upali; Salupo, Terese A.; Wermer, Joseph R.; Knoeppel, David W.; Shore, Sheldon G. (1993). "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. 454: 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. (1982). "Mononuclear hydrido alkyl carbonyl complexes of osmium and their polynuclear derivatives". Inorganic Chemistry. 21 (11): 3955–3960. doi:10.1021/ic00141a019.
    81. Ir(−3) has been observed in Ir(CO)33−; see Predloga:Greenwood&Earnshaw
    82. Ir(VII) has been observed in [(η2-O2)IrO2]+; see C&EN: Iridium dressed to the nines.
    83. Ir(VIII) has been observed in iridium tetroxide (IrO4); see Gong, Yu; Zhou, Mingfei; Kaupp, Martin; Riedel, Sebastian (2009). "Formation and Characterization of the Iridium Tetroxide Molecule with Iridium in the Oxidation State +VIII". Angewandte Chemie International Edition. 48 (42): 7879–7883. doi:10.1002/anie.200902733. PMID 19593837.
    84. Ir(IX) has been observed in IrO+
      4
      ; see Wang, Guanjun; Zhou, Mingfei; Goettel, James T.; Schrobilgen, Gary G.; Su, Jing; Li, Jun; Schlöder, Tobias; Riedel, Sebastian (21 August 2014). "Identification of an iridium-containing compound with a formal oxidation state of IX". Nature. 514 (7523): 475–477. Bibcode:2014Natur.514..475W. doi:10.1038/nature13795. PMID 25341786.
    85. Pt(−1) and Pt(−2) have been observed in the barium platinides Ba2Pt and BaPt, respectively: see Karpov, Andrey; Konuma, Mitsuharu; Jansen, Martin (2006). "An experimental proof for negative oxidation states of platinum: ESCA-measurements on barium platinides". Chemical Communications (8): 838–840. doi:10.1039/b514631c. PMID 16479284.
    86. Pt(I) and Pt(III) have been observed in bimetallic and polymetallic species; see Kauffman, George B.; Thurner, Joseph J.; Zatko, David A. (1967). Ammonium Hexachloroplatinate(IV). Inorganic Syntheses. 9. str. 182–185. doi:10.1002/9780470132401.ch51. ISBN 978-0-470-13240-1.
    87. Au(0) has been observed, see Mézaille, Nicolas; Avarvari, Narcis; Maigrot, Nicole; Ricard, Louis; Mathey, François; Le Floch, Pascal; Cataldo, Laurent; Berclaz, Théo; Geoffroy, Michel (1999). "Gold(I) and Gold(0) Complexes of Phosphinine‐Based Macrocycles". Angewandte Chemie International Edition (21): 3194–3197. doi:10.1002/(SICI)1521-3773(19991102)38:21<3194::AID-ANIE3194>3.0.CO;2-O.
    88. Hg(IV) has been reported in mercury(IV) fluoride (HgF4); see Xuefang Wang; Lester Andrews; Sebastian Riedel; Martin Kaupp (2007). "Mercury Is a Transition Metal: The First Experimental Evidence for HgF4". Angew. Chem. Int. Ed. 46 (44): 8371–8375. doi:10.1002/anie.200703710. PMID 17899620. However, it could not be confirmed by later experiments; see Is mercury a transition metal? Arhivirano 2016-10-12 na Wayback Machine.
    89. Tl(−5) has been observed in Na23K9Tl15.3, see Dong, Z.-C.; Corbett, J. D. (1996). "Na23K9Tl15.3: An Unusual Zintl Compound Containing Apparent Tl57−, Tl48−, Tl37−, and Tl5− Anions". Inorganic Chemistry. 35 (11): 3107–12. doi:10.1021/ic960014z.
    90. Tl(−1) has been observed in caesium thallide (CsTl); see King, R. B.; Schleyer, R. (2004). "Theory and concepts in main-group cluster chemistry". V Driess, M.; Nöth, H. (ur.). Molecular clusters of the main group elements. Wiley-VCH, Chichester. str. 19. ISBN 978-3-527-61437-0.
    91. Tl(+2) has been observed in tetrakis(hypersilyl)dithallium ([(Me3Si)Si]2Tl—Tl[Si(SiMe3)]2), see Sonja Henkel; Dr. Karl Wilhelm Klinkhammer; Dr. Wolfgang Schwarz (1994). "Tetrakis(hypersilyl)dithallium(Tl—Tl): A Divalent Thallium Compound". Angew. Chem. Int. Ed. 33 (6): 681–683. doi:10.1002/anie.199406811.
    92. Pb(−2) has been observed in BaPb, see Ferro, Riccardo (2008). Nicholas C. Norman (ur.). Intermetallic Chemistry. Elsevier. str. 505. ISBN 978-0-08-044099-6. and Todorov, Iliya; Sevov, Slavi C. (2004). "Heavy-Metal Aromatic Rings: Cyclopentadienyl Anion Analogues Sn56− and Pb56− in the Zintl Phases Na8BaPb6, Na8BaSn6, and Na8EuSn6". Inorganic Chemistry. 43 (20): 6490–94. doi:10.1021/ic000333x.
    93. Pb(+1) and Pb(+3) have been observed in organolead compounds, e.g. hexamethyldiplumbane Pb2(CH3)6; for Pb(I), see Siew-Peng Chia; Hong-Wei Xi; Yongxin Li; Kok Hwa Lim; Cheuk-Wai So (2013). "A Base-Stabilized Lead(I) Dimer and an Aromatic Plumbylidenide Anion". Angew. Chem. Int. Ed. 52 (24): 6298–6301. doi:10.1002/anie.201301954. PMID 23629949.
    94. Bi(−2) and Bi(−1) occur in Zintl phases, e.g. (Ca2+)22[Bi4]4−([Bi2]4−)4[Bi3−]8; see Ponou, Siméon (2006). "Germanides, Germanide-Tungstate Double Salts and Substitution Effects in Zintl Phases". Technische Universität München. Lehrstuhl für Anorganische Chemie mit Schwerpunkt Neue Materialien. str. 68.
    95. Bi(I) has been observed in bismuth monobromide (BiBr) and bismuth monoiodide (BiI); see Godfrey, S. M.; McAuliffe, C. A.; Mackie, A. G.; Pritchard, R. G. (1998). Nicholas C. Norman (ur.). Chemistry of arsenic, antimony, and bismuth. Springer. str. 67–84. ISBN 978-0-7514-0389-3.
    96. Bi(+2) has been observed in dibismuthines (R2Bi—BiR2), see Arthur J. Ashe III (1990). Thermochromic Distibines and Dibismuthines. Advances in Organometallic Chemistry. 30. str. 77–97. doi:10.1016/S0065-3055(08)60499-2. ISBN 9780120311309.
    97. Bi(IV) has been observed; see A. I. Aleksandrov, I. E. Makarov (1987). "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. 36 (2): 217–220. doi:10.1007/BF00959349.
    98. Po(V) has been observed in dioxidopolonium(1+) (PoO+); see Thayer, John S. (2010). "Relativistic Effects and the Chemistry of the Heavier Main Group Elements". Relativistic Methods for Chemists. str. 78. doi:10.1007/978-1-4020-9975-5_2. ISBN 978-1-4020-9974-8.
    99. Rn(II) has been observed in radon difluoride (RnF2); see Stein, L. (1970). "Ionic Radon Solution". Science. 168 (3929): 362–4. Bibcode:1970Sci...168..362S. doi:10.1126/science.168.3929.362. PMID 17809133. and Kenneth S. Pitzer (1975). "Fluorides of radon and element 118". J. Chem. Soc., Chem. Commun. (18): 760b–761. doi:10.1039/C3975000760b.
    100. Rn(IV) is reported by Greenwood and Earnshaw, but is not known to exist; see Sykes, A. G. (1998). "Recent Advances in Noble-Gas Chemistry". Advances in Inorganic Chemistry. 46. Academic Press. str. 91–93. ISBN 978-0-12-023646-6. Pridobljeno dne 22 November 2012.
    101. Rn(VI) is known in radon trioxide (RnO3); see Sykes, A. G. (1998). "Recent Advances in Noble-Gas Chemistry". Advances in Inorganic Chemistry. 46. Academic Press. str. 91–93. ISBN 978-0-12-023646-6. Pridobljeno dne 22 November 2012.
    102. Th(I) is known in thorium(I) bromide (ThBr); see Wickleder, Mathias S.; Fourest, Blandine; Dorhout, Peter K. (2006). "Thorium". V Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean (ur.). The Chemistry of the Actinide and Transactinide Elements (PDF). 3 (3rd izd.). Dordrecht, the Netherlands: Springer. str. 52–160. doi:10.1007/1-4020-3598-5_3. ISBN 978-1-4020-3555-5. Arhivirano iz prvotnega spletišča (PDF) dne 2016-03-07.
    103. Th(II) and Th(III) are observed in [ThII{η5-C5H3(SiMe3)2}3] and [ThIII{η5-C5H3(SiMe3)2}3], see Langeslay, Ryan R.; Fieser, Megan E.; Ziller, Joseph W.; Furche, Philip; Evans, William J. (2015). "Synthesis, structure, and reactivity of crystalline molecular complexes of the {[C5H3(SiMe3)2]3Th}1− anion containing thorium in the formal +2 oxidation state". Chem. Sci. 6 (1): 517–521. doi:10.1039/C4SC03033H. PMC 5811171. PMID 29560172.
    104. U(I) has been observed in uranium monofluoride (UF) and uranium monochloride (UCl), see Sykes, A. G. (1990). "Compounds of Thorium and Uranium". Advances in Inorganic Chemistry. 34. Academic Press. str. 87–88. ISBN 978-0-12-023634-3. Pridobljeno dne 22 March 2015.
    105. U(II) has been observed in [K(2.2.2-Cryptand)][(C5H4SiMe3)3U], see MacDonald, Matthew R.; Fieser, Megan E.; Bates, Jefferson E.; Ziller, Joseph W.; Furche, Filipp; Evans, William J. (2013). "Identification of the +2 Oxidation State for Uranium in a Crystalline Molecular Complex, [K(2.2.2-Cryptand)][(C5H4SiMe3)3U]". J. Am. Chem. Soc. 135 (36): 13310–13313. doi:10.1021/ja406791t. PMID 23984753.
    106. Np(II), (III) and (IV) have been observed, see Dutkiewicz, Michał S.; Apostolidis, Christos; Walter, Olaf; Arnold, Polly L (2017). "Reduction chemistry of neptunium cyclopentadienide complexes: from structure to understanding". Chem. Sci. 8 (4): 2553–2561. doi:10.1039/C7SC00034K. PMC 5431675. PMID 28553487.
    107. Pu(II) has been observed in {Pu[C5H3(SiMe3)2]3}−; see 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. (2017). "Identification of the Formal +2 Oxidation State of Plutonium: Synthesis and Characterization ofref name="curium5" {PuII[C5H3(SiMe3)2]3}−". J. Am. Chem. Soc. 139 (11): 3970–3973. doi:10.1021/jacs.7b00706. PMID 28235179.
    108. Pu(VIII) has been observed in PuO4; see Nikonov, M. V.; Kiselev, Yu. M.; Tananaev, I. G.; Myasoedov, B. F. (March 2011). "Plutonium volatility in ozonization of alkaline solutions of Pu(VI) hydroxo complexes". Doklady Chemistry. 437 (1): 69–71. doi:10.1134/S0012500811030104. Also see Kiselev, Yu. M.; Nikonov, M. V.; Dolzhenko, V. D.; Ermilov, A. Yu.; Tananaev, I. G.; Myasoedov, B. F. (17 January 2014). "On existence and properties of plutonium(VIII) derivatives". Radiochimica Acta. 102 (3). doi:10.1515/ract-2014-2146.
    109. Am(VII) has been observed in AmO5-; see 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 Predloga:Greenwood&Earnshaw
    110. 110,0 110,1 110,2 Cm(V), Bk(V), and Cf(V) have been observed in BkO2+, CfO2+, CmO2(NO3)2, BkO2(NO3)2, and CfO2(NO3)2; see Dau, Phuong Diem; Vasiliu, Monica; Peterson, Kirk A; Dixon, David A; Gibsoon, John K (October 2017). "Remarkably High Stability of Late Actinide Dioxide Cations: Extending Chemistry to Pentavalent Berkelium and Californium". Chemistry - A European Journal. 23 (68): 17369–17378. doi:10.1002/chem.201704193. PMID 29024093.
    111. 111,0 111,1 111,2 Kovács, Attila; Dau, Phuong D.; Marçalo, Joaquim; Gibson, John K. (2018). "Pentavalent Curium, Berkelium, and Californium in Nitrate Complexes: Extending Actinide Chemistry and Oxidation States". Inorg. Chem. American Chemical Society. 57 (15): 9453–9467. doi:10.1021/acs.inorgchem.8b01450. PMID 30040397.
    112. Cm(VI) has been observed in curium trioxide (CmO3) and dioxidocurium(2+) (CmO2+); see Domanov, V. P.; Lobanov, Yu. V. (October 2011). "Formation of volatile curium(VI) trioxide CmO3". Radiochemistry. 53 (5): 453–6. doi:10.1134/S1066362211050018.
    113. Cm(VIII) has been reported to possibly occur in curium tetroxide (CmO4); see Domanov, V. P. (January 2013). "Possibility of generation of octavalent curium in the gas phase in the form of volatile tetraoxide CmO4". Radiochemistry. 55 (1): 46–51. doi:10.1134/S1066362213010098. However, new experiments seem to indicate its nonexistence: Zaitsevskii, Andréi; Schwarz, W H Eugen (April 2014). "Structures and stability of AnO4 isomers, An = Pu, Am, and Cm: a relativistic density functional study". Physical Chemistry Chemical Physics. 2014 (16): 8997–9001. Bibcode:2014PCCP...16.8997Z. doi:10.1039/c4cp00235k. PMID 24695756.
    114. Peterson, J. R.; Hobart, D. E. (1984). "The Chemistry of Berkelium". V Emeléus, Harry Julius (ur.). Advances in inorganic chemistry and radiochemistry. 28. Academic Press. str. 29–64. doi:10.1016/S0898-8838(08)60204-4. ISBN 978-0-12-023628-2.
    115. Peterson 1984, str. 55.
    116. Sullivan, Jim C.; Schmidt, K. H.; Morss, L. R.; Pippin, C. G.; Williams, C. (1988). "Pulse radiolysis studies of berkelium(III): preparation and identification of berkelium(II) in aqueous perchlorate media". Inorganic Chemistry. 27 (4): 597. doi:10.1021/ic00277a005.
    117. Es(IV) is known in einsteinium(IV) fluoride (EsF4); see Kleinschmidt, P (1994). "Thermochemistry of the actinides". Journal of Alloys and Compounds. 213–214: 169–172. doi:10.1016/0925-8388(94)90898-2.
    118. Db(V) has been observed in dubnium pentachloride (DbCl5); see H. W. Gäggeler (2007). "Gas Phase Chemistry of Superheavy Elements" (PDF). Paul Scherrer Institute. str. 26–28. Arhivirano iz prvotnega spletišča (PDF) dne 2012-02-20.
    119. Sg(VI) has been observed in seaborgium oxide hydroxide (SgO2(OH)2); see Huebener, S.; Taut, S.; Vahle, A.; Dressler, R.; Eichler, B.; Gäggeler, H. W.; Jost, D.T.; Piguet, D.; et al. (2001). "Physico-chemical characterization of seaborgium as oxide hydroxide" (PDF). Radiochim. Acta. 89 (11–12_2001): 737–741. doi:10.1524/ract.2001.89.11-12.737. Arhivirano iz prvotnega spletišča (PDF) dne 2014-10-25.
    120. Sg(0) has been observed in seaborgium hexacarbonyl (Sg(CO)6); see Even, J.; Yakushev, A.; Dullmann, C. E.; Haba, H.; Asai, M.; Sato, T. K.; Brand, H.; Di Nitto, A.; Eichler, R.; Fan, F. L.; Hartmann, W.; Huang, M.; Jager, E.; Kaji, D.; Kanaya, J.; Kaneya, Y.; Khuyagbaatar, J.; Kindler, B.; Kratz, J. V.; Krier, J.; Kudou, Y.; Kurz, N.; Lommel, B.; Miyashita, S.; Morimoto, K.; Morita, K.; Murakami, M.; Nagame, Y.; Nitsche, H.; et al. (2014). "Synthesis and detection of a seaborgium carbonyl complex". Science. 345 (6203): 1491–3. Bibcode:2014Sci...345.1491E. doi:10.1126/science.1255720. PMID 25237098.
    121. Bh(VII) has been observed in bohrium oxychloride (BhO3Cl); see "Gas chemical investigation of bohrium (Bh, element 107)" Arhivirano 2008-02-28 na Wayback Machine., Eichler et al., GSI Annual Report 2000. Retrieved on 2008-02-29
    122. Hs(VIII) has been observed in hassium tetroxide (HsO4); see "Chemistry of Hassium" (PDF). Gesellschaft für Schwerionenforschung mbH. 2002. Pridobljeno dne 2007-01-31.
    123. Cn(II) has been observed in copernicium selenide (CnSe); see "Annual Report 2015: Laboratory of Radiochemistry and Environmental Chemistry" (PDF). Paul Scherrer Institute. 2015. str. 3.
    124. The Origin of the Oxidation-State, Concept William B. Jensen, J. Chem. Educ. 2007, 84, 1418