Preparation, crystal structure, and reactivity of bis {tris(trimethylsilyl) methyl} magnesium

Abstract

Heating of the lithium magnesate [Li(THF) 2(μ-Br) 2Mg(Tsi)(THF)] (Tsi = (Me 3Si) 3C) under vacuum gives the dialkylmagnesium compound Mg(Tsi) 2, the first two-coordinate magnesium derivative to have been structurally characterized in the solid state. The compound is remarkably thermally stable, not decomposing (or melting) when heated to 350°C. It has a very low reactivity, failing to react in toluene with, for example, CO 2, Me 3SiCl, Me 2SiHCl, MeI, BCl 3 or CH 3COCl, and even with neat CH 3COCl at its boiling point. It does react, though fairly slowly, with I 2 in toluene to give TsiI, and more rapidly with Br 2 to give TsiBr, and with an excess of PhSO 2Cl in toluene at 1OO°C to give TsiCl. It decomposes quickly in the air, and reacts readily with MeOH in toluene to give TsiH without formation of detectable amounts of the intermediate TsiMgOMe, and with O 2 in toluene.