Dimeric and Tetrameric Magnesium Acetylide Complexes. Unique Diorganomagnesium Aggregates and Structural Analogy with Organolithium Aggregates

Treatment of [CpMgMe(Et2O)]2 with phenylacetylene and ferrocenylacetylene at ambient temperature in diethyl ether afforded the tetrameric acetylide complexes [CpMg(μ3-C⋮CPh)]4 and [CpMg(μ3-C⋮CC5H4FeC5H5)]4, respectively. Treatment of [CpMg(μ3-C⋮CPh)]4 with tetrahydrofuran afforded the dimeric acetylide complex [CpMg(μ2-C⋮CPh)(THF)]2. These are the first diorganomagnesium compounds to have close structural analogies with organolithium compounds.