Amidomagnesium cations.

We report the synthesis, structure and reactivity of molecular amidomagnesium cations bearing tris{2-(dimethylamino)-ethyl}amine (Me6TREN). Me6TREN binds to the cationic magnesium centre exhibiting κ4 and κ3 coordination modes in [Me6TREN-Mg-N(SiHMe2)2]+ and [Me6TREN-Mg-N(SiMe3)2]+ respectively. [Me6TREN-Mg-N(SiHMe2)2]+ reacts with benzophenone resulting in the insertion of the carbonyl group across β-SiH bond. The reaction between [Me6TREN-Mg-N(SiMe3)2]+ and CO2 leads to [Me6TREN-Mg-OSiMe3]+, while the reaction with H2O results in [Me6TREN-Mg-OH]22+. Attempts to prepare hydridomagnesium cations from [Me6TREN-Mg-N(SiMe3)2]+ using KH resulted in the precipitation of MgH2 and the isolation of [(Me6TREN)K(THF)3]+.