SYNTHESIS OF THE TETRANUCLEAR CLUSTERS RUM3H(C-CFC)(CO)(12) (M=RU, OS, FC EQUALS FERROCENYL), CONTAINING A FLUXIONAL MU(4)-ACETYLIDE LIGAND- STRUCTURE OF A MIXED-CRYSTAL CONTAINING TETRANUCLEAR (RU4H(C-CFC)(CO)(12)) AND TRINUCLEAR (RU3H(C-CFC)(CO)(9)) RUTHENIUM COMPLEXES

Reactions of acetylide clusters M3H(C=CFc)(CO)(9) (1a, M = Ru; 1b, M = Os; Fc = ferrocenyl) with Ru-3(CO)(12) in refluxing hexane yield the tetranuclear clusters RuM3H(C=CFc)(CO)(12) (2a,b) with a butterfly met al core. The mu(4)-acetylide ligand of these complexes undergoes migra tion, indicated by variable-temperature H-1 and C-13 NMR studies. Comp ounds 2a and 2b are relatively unstable in solution as well as in the solid state and decompose with formation of corresponding trinuclear a cetylide precursors and Ru-3(CP)(12). The molecular structures of la a nd 2a were established by the X-ray diffraction study of a mixed cryst al, which contains both clusters in a 1:1 ratio.