Synthesis,Characterization, and Electrochemical Properties of ORganotransition Metal Fullerene Derivatives Containing dppf Ligands.Crystal Structures of fac-Mo(CO)_3(dppf)(CH_3CN),W(CO)_4(dppf), and mer-W(CO)_3(dppf)(#eta#~2-C_(60))

摘要

Reaction of Mo(CO)3(CH3CN)3 with an equimolar amount of 1,1 '-bis(diphenylphosphino)- ferrocene (dppf) in refluxing acetonitrile gives rise to fac-Mo(CO)3(dppf)(CH3CN) (I) in 51 % yield. While I reacts with [60]fullerene in chlorobenzene at about 90 °C to produce an isomeric mixture offacfmer-Mo(CO)3 (dppf)(1J2_C60)(2) in 21% yield, th-e photolysis of Mo(CO)4(dppf) and [60]fullerene in chlorobenzene at ambient temperature affords 2 in 87% yield. Similarly, mer-W(CO)3(dppf)(1J2_C60) (3), [mer-W(CO)3(dppf)]2(1J2,1J2_C60) (4), mer-W(CO)3(dppf) (1J2-C70) (5), and [mer-W(CO)3 (dpPf)]2(1J2,1J2_C70) (6) can be prepared by photolysis of W(CO)4(dppf) with [60]- or [70]fullerene in 87%, 13%,51%, and 48% yields, respectively. While all the new compounds 1-6 have been characterized by elemental analyses and spectroscopic techniques, the structures of I, W(CO)4(dppf), and 3 have been confirmed by single-crystal X-ray diffraction analyses. The cyclic voltammetric responses of 2 and 3 show that their sequential fullerene-centered reductions are shifted toward more negative potential values by about 0.2 V with respect to those of free C6o. Such a negative shift is quite similar to that previously observed for the related complexes W(CO)3(dppb)(1J2_C60) and Mo(CO)3(dppe)(1J2- C6o). Moreover, the fullerene-centered reductions of 5 are negatively shifted by about 0.1 V with respect to free C7o, thus supporting that the 1J2-coordination of the W(CO)3(dppf) fragment to fullerenes causes a higher electronic interaction with C6o than with C7o.