SYNTHESIS OF MONOSUBSTITUTED PENTAKIS(2,6-DIETHYLPHENYLISO CYANIDE)- COBALT(I) COMPLEXES WITH BIDENTATE TERTIARY PHOSPHINE LIGANDS. I. MONOMETALLIC COMPLEXES

Abstract

Reaction of Co(CNC₆H₃Et₂-2,6)5]BF₄ with bidentate phosphines leads to monosubstituted Co(I) complexes, Co(CNC₆H₃Et₂-2,6)₄(L-L)]BF4, where L-L = Ph₂P(CH₂)n PPh₂, n = 1-4,6; Ph₂PCH₂-CH₂AsPh₂, Ph₂PC₆H₄PPh₂-p, Ph₂PCHdbnd]CHPPh₂-trans. Reaction conditions are such that disubstitution would be possible, but bidentate bridging to form bimetallic complexes is not favoured. Comparison of v(sbnd]N°C) IR, electronic spectra, and molar conductivities with values for Co(CNC₆H₃Et₂-2,6)4L]X, where X = ClO₄, BF₄; L = monodentate triarylphosphine; indicates that these new complexes must also be five-coordinate Co(I) complexes, in which the potentially bidentate phosphine ligands are coordinated through only one P atom. Structures are approximately trigonal bipyramidal in solution and the solid state, with the phosphine ligand occupying an axial position.