Preparation, and Structural and Spectroscopic Characterization of Cobalt(III) Phosphine Complexes of the Type, [Co(CN)4−2<i>n</i>(acac)<i>n</i>(P)2](<i>n</i>−1)+ (acac=Acetylacetonate Ion, <i>n</i>=0,1,2, and P=P(CH3)<i>x</i>(C6H5)3−<i>x</i>, <i>x</i>=0,1,2,3)

Abstract

Abstract A series of the complexes, [Co(CN)4−2n(acac)n(P)2](n−1)+ (acac=acetylacetonate ion, P=P(CH3)x(C6H5)3−x) and several related complexes were prepared. For [Co(acac)2(P)2]+, the P(CH3)3 and P(CH3)(C6H5)2 complexes afford only the cis and the trans isomers, respectively, while the P(CH3)2(C6H5) complex forms both cis and trans isomers. No P(C6H5)3 ligand gave the bis(acac)-type complex. The trans isomers show a strong absorption band in the region of the first absorption band, which is assumed to involve charge transfer transitions between the cobalt(III) ion and a phosphine, while the cis isomers give usual absorption spectra, exhibiting the first d-d absorption band of medium intensity. The methyl and phenyl groups on a phosphorus atom in both cis and trans isomers show triplet signals in the 1H and 13C NMR spectra due to virtual coupling. A trans(P,P) configuration was assigned to all the complexes of [Co(CN)2(acac)(P)2] on the basis of the NMR and electronic spectra. For [Co(CN)4(P)2]−, a trans configuration was assigned from the electronic spectra.