Direct Reduction/Ligand Substitution Reactions in Pentakis(aromatic isocyanide)cobalt(II)

摘要

Reactions of Co(CNR)5 X2#xB7;xH2O (R = aryl; X = ClO4) with excess trialkylphosphite, triarylphosphite, and triarylphosphine are investigated and compared to substitution reactions for Co(CNR)5 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 - (ClO4)2, which is expected to monosubstitute. Excellent yield of Co(CNPh)3{P(OPh)3}2 ClO4but only low yield of Co(CNC6H3-Me2-2,6)4P(OC6H4Cl-p)3 ClO4were obtained, and no product was recovered from P(OPh)3reactions expected to monosubstitute. Triarylphosphine reactions were exclusively disubstitutive, producing expected (e.g., Co(CNC6H4Me-p)3(PPh3)2 ClO4) and unexpected (e.g., Co(CNC6H3Et2-2,6)3(PPh3)2 ClO4) complexes in good yield. Disubstituted Co(I) complexes ofo-EtC6H4NC were prepared from Co(CNC6H4Et-o)5 X2, although Co(CNC6H4Et-o)5 X has not been isolated.