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

Treatment of [CpMgMe(Et 2 O)] 2 with phenylacetylene and ferrocenylacetylene at ambient temperature in diethyl ether afforded the tetrameric acetylide complexes [CpMg(μ 3 -C⋮CPh)] 4 and [CpMg(μ 3 -C⋮CC 5 H 4 FeC 5 H 5 )] 4, respectively. Treatment of [CpMg(μ 3 -C⋮CPh)] 4 with tetrahydrofuran afforded the dimeric acetylide complex [CpMg(μ 2 -C⋮CPh)(THF)] 2 . These are the first diorganomagnesium compounds to have close structural analogies with organolithium compounds.