Alkynyl cobalt complexes. An electrochemical study

Abstract

The preparation and characterisation of the complexes Co 2(CO) 5(PMe 3)(μ-η 2-Me 3SiC 2CCSiMe 3) ( 2) and Co 2(CO) 4(PMe 3) 2(μ-η 2-Me 3SiC 2CCSiMe 3) ( 3) are described. A comparative electrochemical study of the complexes Co 2(CO) 6− n L n (μ-η 2-Me 3SiC 2CCSiMe 3) ( n=0 ( 1); n=1, L=PMe 3 ( 2); n=2, L=PMe 3 ( 3), PPh 2Me ( 4), dppa ( 5), dppm ( 6)) is presented by means of the cyclic and square-wave voltammetry techniques. Substitution of CO by phosphine ligands transforms the Co 2C 2 redox centre from a readily reducible to an easily oxidisable centre and contributes to the stabilisation of the Co–Co bond increasing the lifetime of the radical cations and anions.