Some amino-alkylmagnesium complexes: evidence for three-co-ordinate magnesium

Abstract

Dimethylamine yields the insoluble presumed polymeric amide [(Me₂N)₂Mg]_x on reaction with diethylmagnesium in 1 : 1 molar ratio. Diethyl- and di-isopropyl-amine yield ethylmagnesium derivatives, (EtMgNR₂)_n, from which ether or tetrahydrofuran could not be separated. Insoluble, evidently polymeric, ether-free products, (EtMgNPh₂)_x and (PrⁱMgNPh₂)_x are formed from diphenylamine, and crystalline bis-ether complexes of these are also described. Di-isopropylmagnesium gives a dimeric product, (PrⁱMgNPrⁱ₂)₂, on reaction with di-isopropylamine. Similar crystalline dimers are formed from diethylmagnesium and 2,2,6,6-tetramethylpiperidine, and by the addition of diethylmagnesium to benzylideneaniline.

Di-isopropylmagnesium forms a crystalline t-butyl cyanide complex, (Pr₂ⁱMg·NCBu^t), whereas diethylmagnesium adds to t-butyl and to phenyl cyanide giving products containing azomethine bonds.