REACTIVITY OF RUTHENIUM AND NIOBIUM TRIHYDRIDES WITH GOLD FRAGMENTS - CRYSTAL-STRUCTURE OF THE HEXANUCLEAR RAFT CLUSTER [AU3NB3(MU-H)6 (ETA-C5H4SIME3)6]

The reactions of [MH3(L)L'][M = Ru, L = eta-C5Me5, L' = P (C6H11)3 1; M = Nb, L = L' = eta-C5H4SiMe3 2; M = Nb, L = L' = eta-C5H3(SiMe3)2-1,3 3] with [Au(PPh3)]PF6 produce the trinuclear clusters [L(L')M(mu-H)2{Au(PPh3)}2]PF6[L = eta-C5Me5, L' = P(C6H11)3, M = Ru 4;L = L' = eta-C5H4SiMe3, M = Nb 5; L = L' = eta-C5H3(SiMe3)2, M = Nb 6]. Complex 1 also reacts with one or two equivalents of [Au{N(SiMe3)2}(PPh3)] to yield respectively the neutral derivatives [(eta-C5Me5){(C6H11)3P}Ru(mu-H)2-Au(PPh3)] 7 and [(eta-C5Me5){(C6H11)3P}Ru(mu-H){Au(PPh3)}2] 8. The same reaction with [NbH3(eta-C5H4SiMe3)2] yields the novel hexanuclear raft cluster [Au3Nb3(mu-H)6(eta-C5H4SiMe3)6] 9. Spectroscopic (IR and NMR) data are provided for all the compounds. Crystals of 9 are triclinic, space group P1BAR, with a = 14.927(2), b = 15.083(2), c = 15.632(2) angstrom, alpha = 103.81(1), beta = 99.20(1), gamma = 112.55(1)-degrees, and Z = 2. The molecule consists of a central almost equilateral triangle of gold atoms, with each Au-Au bond bridged by a niobium atom which completes its co-ordination sphere with two eta-C5H4SiMe3 groups. Additionally, each Au-Nb is bridged by one hydride ligand. The most interesting feature of this molecule is the planarity of the six metal atoms.