SYNTHESIS, CHARACTERIZATION AND CRYSTAL-STRUCTURES OF A SERIES OF RUTHENIUM MU(4)-NITRENE CARBONYL CLUSTERS

Methylation of [Ru-3(CO)(10)(NO)](-) anion has led to the isolation of H)(CO)(16)(mu-CO)(mu(4)-NH){mu(3)-eta(2)-C(O)OMe}] 1 in addition to t he major product [Ru-3(CO)(10)(NOMe)] 2. Hydrogenation of 2 in refluxi ng hexane gave [Ru-3(mu-H)(2)(CO)(9)(NH)] 3 and [Ru-3(mu-H)(2)(CO)(9)( NOMe)] 4 in moderate yields, but in the presence of [Ru-3(CO)(12)] it gave [Ru-6(mu-H)(CO)(16)(mu-CO)(2)(mu(4)-NH)(mu-OMe)] 5 and [Ru-5(mu-H )(3)(CO)(13)(mu(4)-NH)(mu(3)-OMe)] 6 in addition. Thermolysis of 2 in toluene at 90 degrees C for 3 h yielded [Ru-4(CO)(12)(mu(4)-N)(mu-OMe) ] 7 and [Ru-6(CO)(16)(mu-CO)(2)(mu(4)-NH)(mu-OMe)(2)] 8. Pyrolysis of 4 at 140 degrees C for 2 h afforded O)(2)(mu(4)-NH)(mu-OMe){mu(3)-eta( 2)-N(H)C(O)OMe}] 9, mu-H)(2)(CO)(14)(mu-CO)(2){mu(5)-eta(2)-NC(O)OMe}] 10 and [Ru-6(CO)(16)(mu-CO)(2)(mu(4)-NH)(mu-OMe)(mu-NCO)] 11 together with the known clusters [Ru4H2(CO)(13)] and [Ru-3(mu-H)(CO)(10)(NH2)] . The crystal structures of 1 and 3-11 have been determined. Clusters 1, 5, 6, 8, 9 and 11 consist of a square-pyramidal 'Ru-4(CO)(8)(mu(4)- NH)' moiety with four ruthenium atoms forming a square-planar base whi ch is capped by a quadruply bridging nitrene ligand. For 1, 5, 8, 9 an d 11, two additional ruthenium fragments bridge the opposite edges of the Ru-4(CO)(8)(mu(4)-NH) metal core to give 'boat' form hexaruthenium nitrene compounds. Compound 6 also has a Ru-4(CO)(8)(mu(4)-NH) moiety , but with only one bridging Ru(CO)(4) fragment at one of the Ru-Ru ed ges of the tetraruthenium plane while the remaining three are bridged by hydrides. Compound 10 comprises a square-pyramidal array of five ru thenium atoms with a Ru(CO)(3) unit bridging one of the Ru-Ru edges of the base. The other side of the square plane is quadruply capped by t he nitrogen atom of a NC(O)OMe ligand with oxygen atom of the acyl gro up bonded to the apical Ru(CO)(3) unit. Compound 7 possesses a butterf ly arrangement of four Ru atoms with the methoxy group bridging the hi nge.