Syntheses, structures and electrochemical study of π-acetylene complexes of cobalt

Abstract

The preparation and characterisation of the complexes [Co 2(CO) 4(PMe 3) 2][Co 2(CO) 6](Me 3SiC 2C 2SiMe 3) ( 4), [Co 2(CO) 4(dppm)][Co 2(CO) 6](Me 3SiC 2C 2H) ( 5), [Co 2(CO) 4(dppa)][Co 2(CO) 6](Me 3SiC 2C 2SiMe 3) ( 6), [Co 2(CO) 4(dppm)] 2[Co 2(CO) 6](Me 3SiC 2CCC 2C 2SiMe 3) ( 7) and [{SiMe 3(Co 2(CO) 4(dppm))C 2} 2(HCC)(1,3,5-C 6H 3)] ( 8) are described. An electrochemical study of the complexes 5– 8 and of the related [Co 2(CO) 4(dppm)] 2(Me 3SiC 2(CC) 2C 2SiMe 3) ( 1), [Co 2(CO) 4(dppa)] 2(Me 3SiC 2C 2SiMe 3) ( 2) and [{SiMe 3(Co 2(CO) 4(dppm))C 2}(HCC) 2(1,3,5-C 6H 3)] ( 3) is presented by means of the cyclic and square-wave voltammetry techniques. Crystals of 8 suitable for single-crystal X-ray diffraction were grown and the molecular structure of this compound is discussed.