Alkynyl cobalt complexes. An electrochemical study

The preparation and characterisation of the complexes Co-2(CO)(5)(PMe3)(mu- eta (2)-Me3SiC2C=CSiMe3) (2) and Co-2(CO)(4)(PMe3)(2)(mu-eta (2)-Me3SiC2C=C SiMe3) (3) are described. A comparative electrochemical study of the comple xes Co-2(CO)(6-n)L-n(mu-eta (2)-Me3SiC2C=CSiMe3) (n = 0 (1); n = 1, L = PMe 3 (2); n = 2, L = PMe3 (3), PPh2Me (4), dppa (5), dppm (6)) is presented by means of the cyclic and square-wave voltammetry techniques. Substitution o f CO by phosphine ligands transforms the Co2C2 redox centre from a readily reducible to an easily oxidisable centre and contributes to the stabilisati on of the Go-Co bond increasing the lifetime of the radical cations and ani ons. (C) 2001 Elsevier Science B.V. All rights reserved.