Synthesis and molecular structures of new silylalkyne triosmium clusters

Abstract

Treatment of the functionalized cluster [Os₃(CO)₁₀(MeCN)₂] with trimethylsilylacetylene quantitatively affords [Os₃(CO)₁₀(HCCSiMe₃)]1 which in refluxing heptane undergoes decarbonylation and hydrogen migration yielding [Os₃H(CO)₉(CCSiMe₃)]2 the structure of which was determined by an X-ray study [triclinic, space group P, a= 9.201(2), b= 13.127(2), c= 9.118(7)Å, α= 107.31(3), β= 98.57(3), γ= 93.18(2)°, Z= 2]. Desilylation of 2 affording [Os₃H(CO)₉(C₂H)] takes place either on silica TLC plates or on stirring in hot methanol. The compound [Os₃H(CO)₁₀(CCSiMe₃)]3 has been prepared through two different routes: (i) reaction of [Os₃H(CO)₁₀Cl] with Li[CCSiMe₃]; (ii) reaction of [Os₃(CO)₁₁(MeCN)] with HCCSiMe₃. It has been characterized by X-ray diffraction studies [monoclinic, space group P2₁/c, a= 13.338(5), b= 9.141(4), c= 18.902(7)Å, β= 109.99(3)°, Z= 4]. On refluxing 3 in heptane, decarbonylation occurs with formation of 2.