SYNTHESIS OF TRIRUTHENIUM CLUSTERS CONTAINING MIXED BRIDGING PHOSPHIDO LIGANDS - X-RAY CRYSTAL-STRUCTURES OF [RU-3(CO)(7)(MU-H)(MU-PBU2T)(MU-PCY2)(2)] AND THE ELECTRON-DEFICIENT COMPLEX (MU-CO)(CO)(5)(MU-H)(2)(MU-PBU2T)(2)((BU2PH)-P-T)]

The reaction of the triruthenium cluster [Ru-3(CO)(8)(mu-H)(2)(mu-PBu2 t)(2)] (1) with Cy2PH has been investigated. Complex 1 reacts spontane ously with the phosphine in toluene at room temperature. Subsequent he ating under reflux for a short time affords the two novel mixed phosph ido-bridged complexes [Ru-3(CO)(7)(mu-H)(mu-PBu2t)(mu-PCy2)(2)] (2) an d [Ru-3(CO)(8)(mu-H)(2)(mu-PBu2t)(mu-PCy2)] (3) in good yields beside the electron-deficient 46-electron cluster (mu-CO)(CO)(5)(mu-H)(2)(mu- PBu2t)(2)((Bu2PH)-P-t)] (4) as minor product. Compound 1 reacts with s toichiometric amounts of (Bu2PH)-P-t to give 4 in nearly quantitative yield. The metal cluster 2 was also synthesized directly by reaction o f [Ru-3(CO)(8)(mu-H)(2)(mu-PCy2)(2)] (5) With (Bu2PH)-P-t in refluxing toluene. 5 reacts with Ph2PCH2PPh2 (dppm) in toluene under reflux to give [Ru-3(CO)(6)(mu-H)(2)(mu-PCy2)(2)(mu-dppm)] (6), but is formed on ly in traces under these conditions. The characterization of the compo unds 2, 3 and 4 was carried out by spectroscopic means and the X-ray c rystal structures of 2 and 4 are reported. (C) 1998 Elsevier Science S .A.