CLUSTER CHEMISTRY .81. REACTIONS OF RU3(MU-DPPM)(CO)10 WITH C2(CO2ME)2 - X-RAY STRUCTURES OF RU3(MU-3-C4(CO2ME)4)(MU-DPPM)(CO)6, RU3(MU-H)2(MU-3-C2(CO2ME)2)(MU-DPPM)(CO)7 AND RU4(MU-3-H)(MU-4-C2(CO2ME)2)-(MU-PPH2CH2PPH(C6H4))(CO)9

Several complexes have been obtained from reactions between Ru3(mu-dppm)(CO)10 and C2(CO2Me)2, including Ru3{mu-3-C2(CO2Me)2}(mu-dppm)(mu-CO)(CO)7 (7), Ru3{mu-3-C4(CO2Me)4}(mu-dppm)(CO)6 (8), Ru4{mu-4-C2(CO2-Me)2}(mu-dppm)(CO)10 (11) and Ru4(mu-3-H){mu-4-C2(CO2Me)2}{mu-PPh2CH2PPh(C6H4)}(CO)9 (10). A complex related to 10, containing a C4(CO2Me)4 ligand, was obtained directly from Ru3(mu-3-PPhCH2PPh(C6H4)}(CO)9 and the alkyne. Ready replacement of CO by 2H occurred in the reaction of 7 with H-2, which afforded Ru-3(mu-H)2{mu-3-C2(CO2Me)2}(mu-dppm)(CO)7 (9). Complexes 8, 9 and 10 were characterised by single-crystal X-rav studies: in 8. the C4(CO2Me)4 ligand forms a ruthenacyclopentadiene system which interacts in the eta-4 mode with the second Ru atom, and via an ester CO group with the third Ru atom. In 9, the alkyne is attached to the RU3 cluster in the mu-3-eta-2-parallel-to mode, while in 10, it is incorporated into an octahedral C2Ru4 cluster; the metallated dppm ligand bridges an edge of one of the wings of the Ru4 butterfly. Complexes 10 and 11 were obtained in only 1% and 2% yield, respectively.