NEW GENERAL SYNTHETIC STRATEGY OF FULVALENE HOMODINUCLEAR ZWITTERIONS- ELECTROCHEMICAL-BEHAVIOR OF (ETA(5)-ETA(5)-(C5H3CO2ME)(2))MO-2(CO)(6)R-2 (R = I, ME)

The reaction of Li-2[eta(5):eta(5);(C5H3CO2Me)(2))Mo-2(CO)(6)] (from t rans-(eta(5):eta(5)-(C5H3CO2Me)(2))Mo-2-(CO)(6)) (1) with MeI yields ( eta(5):eta(5)-(C5H3CO2Me)(2))Mo-2(CO)(6)Me-2 (3). The reaction of cis- (eta(5):eta(5)-(C5H3CO2Me)(2))Mo-2(CO)(6) (2) with I-2 leads to the fo rmation of (eta(5):eta(5)-(C5H3CO2Me)(2))Mo-2(CO)(6)I-2 (4). The X-ray structure of 4 has been determined; The reactions of 1 with P-donor n ucleophiles (PPhMe2, PPh2Me, P(n-Bu)(3), and PMe3) and (eta(5):eta(5)- (C10H8)M-2(CO)(6) (M = Mo and W) with PMe3, in the presence of 1 equiv of Me3NO, produce CO labilization and formation of the dinuclear zwit terions (eta(5):eta(5)-(C5H3CO2Me)(2))Mo-2(CO)(5)L-2 and (eta(5):eta(5 )-(C10H8)M-2(CO)(5)(PMe3)(2) (M = Mo and W) 5, 6, 7, 8, 9, and 10, res pectively). The dimer [(eta(5)-C5H4CO2Me)Mo(CO)(3)](2) (11) was obtain ed by reaction of Mo(CO)(6) with sodium carbomethoxy cyclopentadienide in THF followed by oxidation with ferric sulfate. The reaction of 11 with PPh2Me in the presence of 1 equiv of Me3NO gives the disproportio nation species )(2)(PPh2Me)(2)(+)][eta(5)-C5H4CO2Me)Mo(CO)(3)(-)] (12) . The electrochemical study of 3 and 4 is reported. Two distinct catho dic waves are observed in the voltammetric reduction of 4, the less ne gative one with a coupled anodic peak at high sweep rate in PC.