Syntheses of tris(t-butylisocyanide)bis(tri-p-dimethyl- aminophenylphosphine)cobalt(I) and cobalt(II) perchlorates: a reversal of the usual stabilities of cobalt oxidation states

The complexes [Co(CNCMe₃)₃{P(C₆H₄NMe₂-p)₃}₂](ClO₄)₂ and [Co(CNCMe₃)₃{P(C₆H₄NMe₂ -p)₃}₂]ClO₄ are reported. The Co(II) complex, formed by reaction of excess triarylphos-phine with the alkylisocyanide Co(II) complex, is stable and the favoured product. The Co(I) complex, formed by hydrazine reduction of the Co(II) complex, has limited stability in solution, readily oxidizing to the Co(II) species. Upon prolonged irradiation of the Co(II) complex in acetone, [Co{OP(C₆H₄NMe₂-p)₃}₄](ClO₄)₂ is produced.