Donald C. Bradley, Ian S. Harding, Izaque A. Maia and Majid Motevalli
Dialkylaluminium µ-dialkylamido compounds of formula (R12AlNR22)2 (R1 = Me, Et, Pri, Bui or But; R2 = Me, Et, Pri, Bui or Ph) were synthesized by alkane or arene elimination from the corresponding adduct of formula R13Al·NHR22. The crystal structures of the following dimeric compounds were determined: (Me2AlNEt2)2, (Me2AlNBui2)2, (Et2AlNPri2)2, (Pri2AlNMe2)2, (Pri2AlNEt2)2, (Bui2AlNMe2)2, (Bui2AlNEt2)2 and also the mononuclear compound Et2Al(OEt2)NPh2. The general trends identified in these structures suggest that the environments around aluminium and nitrogen are affected primarily by their closest alkyl groups, i.e. R1 and R2 respectively, but that loss of a centre of symmetry is dependent only on R2. Infrared data can also show the presence of a molecular centre of symmetry. Mass spectroscopic data suggest that dimers are present in the gas phase but they are partially dissociated into monomers which in turn fragment into the more stable species [R1AlNR22]+. The NMR data show that aromatic solvents shield the R2 protons causing downfield chemical shifts. Low-pressure (10-2 Torr) thermal decomposition (500–600 °C) to produce films of aluminium nitride was studied.