Synthesis, Characterization and Electrochemical Properties of Substituted Half-Sandwich Cobalt(I) Complexes

Organocobalt compounds C 5 H 4 RCoLL' (2a),(2b), (2b') and (2c) (L = CO, L' = PR 3 ; a, R = -COOC(CH 3 )˭CH 2 ; b, R = -COOCH 2 C 6 H 5 ; c, R = -COOCH 2 CH˭CH 2 .) were prepared and characterized. The electronic spectra and the electrochemical properties of compounds (2a), (2b), (2b'), (2c) and their analogues (la), (lb), (lc), (ld) (L = L'˭CO; d, R = -CH 2 COOCH 2 CH˭CH 2 ) and (3) (L = L' = PR 3 , R = -COOCH 2 C 6 H 5 ) were also studied. It was found that (2a), (2b), (2b'), (2c) exhibited two reversible peaks during electrochemical oxidation which were attributed to the formation of two reaction intermediates. Their dicarbonyl or bis(phosphine) analogues did not show such reversible peaks during electrochemical oxidation. The compounds (2a), (2b), (2b') and (2c) exhibited the best ability of anti-oxidation among the three types of the organocobalt compounds.