Synthesis of high nuclearity cluster alkynes under mild reaction conditions; the X-ray crystal structures of [Os6(CO)17(µ-H)(µ4-η-CCEt)], [Os6(CO)17(µ4-η2-HCCEt)], and [Os6(CO)16(µ3-η-MeCCEt)]

Abstract

Reaction of the labilised cluster [Os₆(CO)₁₇(NCMe)]with the terminal alkynes HCCR (R = Me, Et, or Ph) affords the isomeric alkyne substituted clusters [Os₆(CO)₁₇(µ-H)(µ₄-η-CCR)][R = Me (1), Et (3), or Ph (5)] and [Os₆(CO)₁₇(µ₄-η²-HCCR)][R = Me (2), Et (4), or Ph (6)], and under similar conditions the disubstituted alkynes RCCR′(R = Me or Ph; R′= Me, Ph, or Et) give [Os₆(CO)₁₆(µ₃-η-RCCR′)][R = R′= Me (7); R = R′= Ph (8); R = Me, R′= Et (9)] as the major product; the structures of complexes (3), (4), and (9) have been established by X-ray diffraction studies.