Thiomethylmagnesium Chlorides: Synthesis via Hg–Mg Transmetallation and Crystallization of a Grignard Compound as 1/1 Adduct of [Mg(CH2SPh)2(thf)3] and [MgCl2(thf)4]

Thiomethylmercury chlorides 2 Hg(CH₂SMe)Cl · HgCl₂ and Hg(CH₂SPh)Cl react with magnesium in thf to give the Grignard compounds Mg(CH₂SR)Cl (R = Me ( 1 ), Ph ( 2 )) in nearly quantitative yields. From thf/n‐hexane solutions of 2 precipitate at –40 °C colorless crystals of the composition Mg(CH₂SPh)Cl · 3.5 thf ( 2 ′). X‐ray structure determination revealed, that the unit cell contains separated molecules of [Mg(CH₂SPh)₂(thf)₃] and [MgCl₂(thf)₄]. In the [Mg(CH₂SPh)₂(thf)₃] molecules magnesium is distorted trigonal‐bipyramidally coordinate. Two PhSCH₂ and one thf ligand occupy the equatorial positions and two further thf ligands the apical ones. In the [MgCl₂(thf)₄] molecules Mg displays an octahedral coordination with chloro ligands in mutual trans position. Temperature dependent NMR measurements of 2 reveal that in thf the Schlenk equilibrium operates; the composition of the equilibrium mixture at room temperature was estimated to be 89% Mg(CH₂SPh)Cl and 11% Mg(CH₂SPh)₂.