NMR, X-ray and Mass-spectrometry: characterization of some heteroleptic aluminium alkoxide complexes

Among the synthesized (CH3)2AlOR compounds (R=CH2CH2OCH3 (1), CH(CH3)CH2OCH3 (2), CH2CH2OCH(CH3)2 (3), CH(CH3)CH2OC(CH3)3 (4)), 2 and 4 have been characterized by 1H and 27Al NMR spectroscopy and X-ray diffraction, while 1, 2 and 3 have been analysed by mass spectrometric measurements with a mass spectrometer equipped with a special designed input system imitating a CVD reactor. While in the solid state it is unequivocally clear that the compounds are present in the form of an oxygen-bridged dimer with a five-coordinated aluminum center, in solution an equilibrium exists between two fluxional species containing tetra and penta coordinated Al atoms respectively.