DIRECT REDUCTION-LIGAND SUBSTITUTION-REACTIONS IN PENTAKIS(AROMATIC ISOCYANIDE)COBALT(II)

Reactions of [Co(CNR)5] X2•xH20 (R = aryl; X = CIO4, BF4) with excess trialkylphosphite, triarylphosphite, and triaryl-phosphine are investigated and compared to substitution reactions for [Co(CNR)s| X with phosphorus ligands. Direct reduction/ligand substitution reactions strongly favor disubstitution. Reaction with trialkylphosphite produced disubstituted products in satisfactory to good yields, but no crystalline product was obtained from [Co (CNC6H3Et2~2,6) 5] - (CIO4)2> which is expected to monosubstitute. Excellent yield of [Co(CNPh)3{P(OPh)3)2! CIO4 but only low yield of [Co(CNC6H3-Me2-2,6) 4P (OCglCl-p) 3] CIO4 were obtained, and no product was recovered from P(0Ph)3 reactions expected to monosubstitute. Triarylphosphine reactions were exclusively disubstitutive, producing expected (e.g., [CoCCNCgiMe-p) 3 (PPI13)2] CIO4) and unexpected (e.g, [Co(CNC6H3Et2-2,6)3(PPh3)2] CIO4) complexes in good yield. Disubstituted Co(I) complexes of o-EtCgH4NC were prepared from [Co(CNC6H4Et-o)5] X2, although [Co(CNC6H4Et-o) 5] X has not been isolated. © 1979, Taylor & Francis Group, LLC. All rights reserved.