Other oxidation states of Co

The formal oxidation state —1 may be recognized in the tetrahedral molecule Co(CO)3NO (p. 772). Little appears to be known about the structures of compounds of Co(0). 

Co(iii). With very few exceptions, such as the heteropolyacid ion (C0W12O40) (p. 436), the bond arrangement is octahedral. We deal separately with examples of the extremely numerous cobaltammines. High-spin Co(iii), d , is rare it occurs in K3C0F5 but not in Co(NH3)3p3 or most cobaltammines. 

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