SYNTHESIS, STRUCTURE AND REACTIVITY TOWARD TETRAFLUOROBORIC ACID OF ANEW HETEROBIMETALLIC RHENIUM-IRIDIUM POLYHYDRIDE COMPLEX, (CO)(PPH3)2RE(MU-H)3IRH(PPH3)2

The reaction of [K][ReH6(PPh3)2] with IrCl(CO)(PPh3)2 leads to formati on of the complex (CO)(PPh3)2-Re(mu-H)3IrH(PPh3)2 (1) in 36% yield. It s structure has been established by variable temperature H-1 and P-31 NMR and X-ray diffraction; it consists of two distorted octahedra shar ing a face containing three bridging hydrides. The iridium atom is bon ded to a terminal hydride and to two phosphine ligands. The position o f the hydrides has been calculated using the program HYDEX. Crystallog raphic data for 1: monoclinic C2h5-P2(1)/n, a = 14.818(3) angstrom, b = 20.750(2) angstrom, c = 21.693(3) angstrom; beta = 96.29(2)-degrees, V = 6629 (2) angstrom3, Z = 4; R= 0.0374, R(W) = 0.0435 for 3845 obse rvations and 406 variable parameters. The compound 1 reacts with HBF4. OMe2 to give [(CO)(PPh3)2HRe-(mu-H)3IrH(PPh3)2][BF4] which has been is olated as its tetraphenylborate salt and characterized by variable tem perature H-1 and P-31 NMR spectroscopy. Protonation has induced the fo rmation of rhenium-terminal hydride bond.