1H, 13C and 29Si NMR study of acetylide and parallel alkyne substituted Ru3 and Os3 clusters derived from HC?CR (R=SiMe3, SiPh3 and CMe3). X-ray crystallographic study of [(?-H)M3(CO)9(CCR)] (M=Ru, R=SiMe3, SiPh3; M=Os, R=SiPh3, CMe3) and [Ru3(?-CO)(CO)9(HCCR)] (R=CMe3)

A series of alkyne parallel ?3-?2-(//) substituted trinuclear cluster derivatives has been synthesized, containing the alkynes (HC?CR, R=SiMe3, SiPh3 and tBu) coordinated to Ru3 and Os3 units and then converted into the corresponding chemically related acetylide derivatives. A 1H, 13C and 29Si NMR study was carried out for all the complexes and the results are also analyzed in comparison with results of Extended Hückel Molecular Orbital calculations carried out on the complexes and the free alkynes. In the acetylide derivatives, 13C?1H and 187Os?1H couplings involving the hydride, were measured. The 13C?29Si couplings for all the derivatives which contain silicon shows the changes in hybridization of the C?. The structures of [(?-H)Ru3(CO)9(CCR)] (R=SiMe3 and SiPh3) and [(?-H)Os3(CO)9(CCR)] (R=SiPh3 and CMe3) and [Ru3(CO)10(HCCR)] (R=CMe3) were determined by single crystal X-ray diffraction methods.