A NEW ROUTE TO BINUCLEAR AND TRINUCLEAR RUTHENIUM CARBONYL DERIVATIVES - STRUCTURES OF [RU3(CO)6(MU-PH2PCH2PPH2)3] AND ITS PROTON ADDUCT

Reduction of ruthenium(III) acetate, prepared in situ from RUCl3.3H2O and silver acetate, with NaBH4 in the presence of dppm = Ph2PCH2PPh2 a nd CO gives a good route to [Ru2(mu-CO)(CO)4(mu-dppm)2] (1) and also g ives [Ru3(CO)6(mu-dppm)3] (2) in low yield. Complex 2 is very readily protonated to give [Ru3(mu-H)(CO)6(mu-dppm)3]+ (3). The structures of both 2 and 3 have been determined by X-ray diffraction: 2, space group P2(1)/n, a = 24.984(3) angstrom, b = 19.433(3) angstrom, c = 14.724(2 ) angstrom, beta = 90.747(9)-degrees, Z = 4, R (R(w)) = 0.051 (0.040); (3)BF4.C2H4Cl2.1.5C5H12, space group P1BAR, a = 14.810(2) angstrom, b = 21.801(2) angstrom, c = 13.847(1) angstrom, alpha = 107.67(1)-degre es, beta = 91.54(4)-degrees, gamma = 89.86(1)-degrees, Z = 2, R (R(w)) = 0.075 (0.082). The hydride ligand in 3 is shown to be edge-bridging , and the cluster cation 3 is fluxional with the hydride migrating rap idly between edges and from side to side of the Ru3 triangle even at - 80-degrees-C.