Crystal structures and unusual solution behaviour of diastereomeric aluminium and gallium complexes of chiral amines [Me3M · RR*NH]

Six highly air and moisture sensitive diastereomeric adducts of trimethylaluminium and gallium have been formed from reaction with the three commonly used chiral secondary amines; ((S)-Ph(Me)CH)(PhCH2)NH, (R,R)-Ph(Me)CH2NH and (S)-Ph(Me)CH(CH2CHCH2)NH, and their structures determined by single crystal X-ray diffraction. They were all found to be four coordinate monomers crystallising in the space group P212121. Investigation of their solution structures by multinuclear and variable temperature NMR indicated that in contrast to the others (S,R)-[Me3Al · HN(CHMePh)(CH2Ph)] appeared to form two different isomers in toluene solution.