Redox behavior of the molybdenum and tungsten metallafullerenes Mo(CO)3(dppe)(η2-C60) (dppe=bis-(1,2-diphenylphosphino)ethane) and W(CO)3(dppb)(η2-C60) (dppb=bis-(1,2-diphenylphosphino)benzene)

Electrochemistry of M(CO)3(diphosphine)(η2-C60) (M=W, diphosphine=1,2-bis(diphenylphosphino)benzene (1); Mo, diphosphine=1,2-bis(diphenylphosphino)ethane (2)) shows that they undergo reversibly three fullerene-centred reductions at potential values which are more negative by about 0.2 V with respect to the corresponding steps in free C60. EPR measurements on the electro-generated monoanions [1]− and [2]− seem to support that the unpaired electron, although delocalized on the fullerene moiety, assumes a non-negligible metallic character, thus suggesting that the LUMOs of the two complexes might be significantly contributed to by the metallic fragments.