FORMATION AND REACTIONS OF A DIRHODIUM COMPLEX INCORPORATING A SECONDARY PHOSPHINE - INTRAMOLECULAR PROTON-TRANSFER, CNR ADDITION, AND CONVERSION TO THE TRINUCLEAR CLUSTER (ETA-C5H5)2RH2IR(MU-PPH2)(CO)2(CF3C2CF3)

The reaction of (eta-C5H5)2Rh2(mu-Co)(mu-eta2-CF3C2CF3) (1) with PPh2H at room temperature gives the new dinuclear species (eta-C5H5)2Rh2(CO)(PPh2H)(mu-eta1:eta1-CF3C2CF3) (2). In solution, or in the absence of an atmosphere of CO, facile conversion of 2 to (eta-C5H5)2Rh2(mu-PPh2){mu-eta1:eta2-C(CF3)C(CF3)H} (3) occurs via an intramolecular proton shift accompanied by decarbonylation. This process is irreversible. Complex 3 reacts with CNR (R = i-Pr, t-Bu) to produce the phosphaalkylidene species (eta-C5H5)2Rh2(CNR){PPh2C(CF3)C(CF3)H} (4), presumably via nucleophilic attack of CNR at a Rh center and migration of the alkylidene moiety to the mu-PPh2 group. Reaction of 2 with n-BuLi and subsequently [Ir(cod)Cl]2 yields the new heteronuclear cluster compound (eta-C5H5)2Rh2Ir(mu-PPh2)(CO)2(CF3C2CF3) (6), which was characterized by X-ray crystallography. Crystal data for 5: monoclinic, P2(1)/c, a = 9.728 (1) angstrom, b = 16.020 (2) angstrom, c = 17.649 (2) angstrom, beta = 91.95 (3)-degrees, Z = 4, final R = 0.041 for 5195 "observed" reflections.