Cobalt through Meitnerium

Abstract

Oxidation numbers: (−I) in [Co(CO)₄]– (II) in Co²⁺, (III) in Co³⁺ and (IV) in CoO₂. In [Co(CO)₃(NO)] (from a non-aqueous source) we could, without further structural information, classify Co as Co⁰ but might also well see it as [Co–(CO)₃(NO⁺)] in spite of the electronegativities (because NO⁺ is isoelectronic with the very stable N₂ and CO), or as [Co+(NO^–)(CO)₃], assigning the metal as usual a positive oxidation state. (These assignments, within molecules, are partly but not entirely arbitrary.) Various experiments and calculations, not described here, also reveal NO both as a primarily neutral radical, e.g., in [Ir³⁺(Cl^–)₅(NO⁺)] and as NO⁺ in [Ru³⁺(Cl^–)₅(NO⁺)]. See 6.1.2 and 8.1.2 Oxidized nitrogen also.