Reaction of [Os3H2(CO)10] with the diyne Me3SiC2C2SiMe3 and the reactivity of the products towards [Co2(CO)8]: the X-ray structures of [Os3(μ-H)(CO)10{μ-η1-η2-HC2(SiMe3)C2(SiMe3)}], [Os3(μ-CO)(CO)9{μ3-η2-Me3SiC2C2SiMe3}] and [Os3(μ-H)(CO)9{μ3-η1:η2-;μ-η2-

The reaction of [Os3H2(CO)10] with Me3SiC2C2SiMe3 affords both [Os3(μ-H) (CO)10{μ-η1-η2-HC2(SiMe3)C2(SiMe3)}] (1) and [Os3(μ-CO)(CO)9(μ3-η2-Me3SiC2C2SiMe3)] (2) in good yield, 2 being favoured with an excess of diyne. In 1, one edge of the triosmium unit is bridged by the vinyl moiety of a transformed bis(trimethylsilyl)-1,4-butadiyne ligand that has undergone a hydride transfer and a 1,2-trimethylsilyl shift. Compound 2 is selectively desilylated in methanol to produce a single isomer of the known cluster [Os3(μ-CO)(CO)9{μ3-η2-HC2C2SiMe3}] (3). Whereas reaction of 3 with [Co2(CO)8] results in the production of the previously reported cluster [Os3{μ3-η2-:μ-η2-(Me3SiC2C2H)[Co2(CO)6]}(μ-CO)(CO)9] (4) and a second product [Os3(μ-H)(CO)9{μ3-η1:η2-;μ-η2-Me3SiC2C2[Co2(CO)6]}] (5), the reaction of 1 and 2 results in recovery of the starting material or transfer of the alkyne ligand to the Co2 unit. Compound 4 undergoes a transformation to 5 in visible light. All the cluster complexes have been characterized spectroscopically, and the solid-state structures of 1, 2 and 5 have been determined by single-crystal X-ray diffraction.