Oxidative addition of an imidazolium cation to an anionic gallium(I) N-heterocyclic carbene analogue: Synthesis and characterisation of novel gallium hydride complexes

The reactions of N-heterocyclic carbenes and imidazolium salts towards an anionic gallium(I) heterocycle, [:Ga{[N(Ar)C(H)]2}]−, Ar=C6H3Pr2i-2,6, have been studied. No reactions with N-heterocyclic carbenes were observed, though the reaction of the gallium heterocycle with the imidazolium salt, [HC{N(Mes)C(H)}2]Cl, IMesHCl, Mes = C6H2Me3-2,4,6, led to oxidative insertion of the Ga(I) centre into the imidazolium C–H bond and formation of the gallium hydride complex, [HGa{[N(Ar)C(H)]2}(IMes)]. When this reaction was carried out in the presence of traces of water, partial hydrolysis of [HGa{[N(Ar)C(H)]2}(IMes)] resulted in the formation of the hydroxy-bridged, anionic gallium hydride complex, [{HGa[N(Ar)C(H)]2}2OH][(IMes)2H]. Both compounds have been spectroscopically and structurally characterised.

Graphical abstractThe reaction of an anionic gallium(I) heterocycle, [:Ga{[N(Ar)C(H)]2}]−, Ar=C6H3Pr2i-2,6, with an imidazolium salt, [HC{N(Mes)C(H)}2]Cl, IMesHCl, Mes = C6H2Me3-2,4,6, leads to oxidative insertion of the gallium(I) centre into the imidazolium C–H bond and the formation of an N-heterocyclic carbene coordinated gallium hydride complex.Figure optionsDownload full-size imageDownload as PowerPoint slide