Bis-NHC Aluminium and Gallium Dihydride Cations [(NHC)2EH2]+ (E = Al, Ga)

Abstract

The NHC alane and gallane adducts (NHC)·AlH2I (NHC = Me2ImMe 7, iPr2Im 8, iPr2ImMe 9) and (NHC)·GaH2I (NHC = Me2ImMe 10, iPr2ImMe 11, Dipp2Im 12; R2Im = 1,3-di-organyl-imidazolin-2-ylidene; Dipp = 2,6-diisopropylphenyl; iPr = isopropyl; Me2ImMe = 1,3,4,5-tetra-methyl-imidazolin-2-ylidene) were prepared either by the simple yet efficient reaction of the NHC adduct (NHC)·AlH3 with elemental iodine or by the treatment of (NHC)·GaH3 with an excess of methyl iodide at room temperature. The reaction of one equivalent of the group 13 NHC complexes with an additional equivalent of the corresponding NHC afforded cationic aluminium and gallium hydrides [(NHC)2·AlH2]+I− (NHC = Me2ImMe 13, iPr2Im 14, iPr2ImMe 15) and [(NHC)2·GaH2]+I− (NHC = Me2ImMe 16, iPr2ImMe 17) and the normal and abnormal NHC coordinated compound [(Dipp2Im)·GaH2(aDipp2Im)]+I− 18. Compounds 7–18 were isolated and characterized by means of elemental analysis, IR and multinuclear NMR spectroscopy and by X-ray diffraction of the compounds 7, 9, 10, 15, 16 and 18.