CLUSTER CHEMISTRY .80. REACTIONS OF RU5(MU-5-C2PPH2)(MU-PPH2)(CO)13 WITH 1,3-BUTADIENE - ADDITION TO C-ALPHA AND FORMATION OF A MU-4-CYCLOHEXENYNE COMPLEX - X-RAY STRUCTURES OF RU5(MU-4-CC(PPH2)CH2-ETA-3-CHCHCH2)(MU-PPH2)(MU-CO)(CO)11, RU5(MU-4-CC(PPH2)CHCH=CHME)(MU-PPH2)(MU-CO)2(CO)9 AND RU5(MU-4-C6H6)(MU-PPH2)2(CO)11

Reactions between Ru5(mu(5)-C2PPh2)(mu-PPh2)(CO)13 (1) and 1,3-butadiene have given Ru5-{mu(4)-CC(PPh2)CH2-eta(3)-CHCHCH2}(mu-PPh2)(mu-CO)(CO)11, (7), Ru5{mu(4)-CC(PPh2)CHCH = CHMe}(mu-PPh2)(mu-CO)2(CO)9 (8), and Ru5(mu(4)-C6H6)(mu-PPh2)2(CO)11 (9), in addition to the previously described metallated benzoyldiphenylphosphine derivative, Ru4{mu(4)-C6H3C(O)PPh2}(mu-PPh2)(CO)9(eta(3)-C4H7) (6). Complexes 7 and 8 contain isomeric tertiary phosphine ligands formed by addition of the 1,3-diene to C(alpha) of the C2PPh2 ligand in 1. The metal cores are based on square pyramidal Ru5 clusters, but in 7, two apical-basal Ru-Ru vectors are long, formally 1-e, bonds. In 9, the cluster is an Ru-capped C2Ru4 octahedron, the two carbons forming part of a cyclohex-1-en-4-yne ligand generated by cycloaddition of the diene to a C2 fragment with concomitant P-C bond cleavage. Complexes 7, 8 and 9 were fully characterised by single crystal X-ray studies.