SYNTHESES AND CRYSTALLOGRAPHIC CHARACTERIZATIONS OF RU4(CO)8(MU-3-C6H2R2O2)2 (R=H,T-BU), COMPLEXES CONTAINING 1,2-SEMIQUINONE LIGANDS WHICH BRIDGE THROUGH OXYGEN AND ETA(6)-C6 RINGS

The reactions of Ru3(CO)12 with catechol and with 3,5-di-tert-butyl-1,2-benzoquinone yield the three clusters Ru4(CO)8(mu3-O2C6H2R2)2 (R = H, t-Bu) which differ in the arrangement of metal atoms but which all contain mu3-semiquinone ligands coordinated via terminal and bridging O atoms and a pi-eta6-C6 ring. The substitution products Ru4(O2CrH2(t-Bu)2)2(CO)7L (L = THF, NCMe, PPh3, C2Ph2) were prepared from one isomer.