Stepwise synthesis of [Os 3(CO) 8(R 2C 2)(R′ 2C 2)] from [Os 3(CO) 10(R 2C 2)] under mild conditions, x-ray crystal structure of [Os 3(CO) 8(Ph 2C 2) 2]; a bis(alkyne) without an osmacyclopentaidiene ring

Abstract

Treatment of a solution of [Os 3(CO) 10(R 2C 2)] (R = Me ( 1, R = Ph ( 2)) in CH 2Cl 2 with Me 3No/MeCN in the presence of R′ 2C 2 affords the new organometallic cluster [Os 3(CO) 8(R 2C 2)(R′ 2C 2)] (R = R′ = Me ( 3), R = R′ = Ph ( 4) and R = Ph, R′ = Me ( 5)). A single crystal X-ray analysis of compound 4 has established a triangular metal framework with both the alkyne units coordinated in a μ 3-η 2-‖-mode. In toluene, at 80°C, compound 4 undergoes rearrangement to the known compound, [Os 3H(CO) 8(Ph)C 2(C 6H 4))] ( 6) in which CC bond formation has occurred to produce an osmacyclopentadiene ring.