Cyclic imino derivatives of aluminium, gallium, and indium dialkyls

Abstract

A series of volatile cyclic imino-compounds, [[graphic omitted]·MR₂]_n, (x= 1, 2, 3, or 4; M = Al, Ga, or In; R = Me, Et, or Buⁱ) has been prepared and characterized by elemental analysis molecular-weight determinations, and ¹H n.m.r. and mass spectroscopic measurements. The effects of varying x, M, and R on the degree of association, n, of the monomer units have been studied. In all cases with x= 1 and R = Me the compounds are trimeric. Replacement of methyl groups in the aziridino-derivatives by ethyl groups yields a dimeric product for the gallium compound but the bulkier isobutyl groups are required to effect a similar change in association for the aluminium derivative. When x= 2, 3, or 4 dimeric compounds were obtained with the one exception of azetidino-aluminium dimethyl. For this compound a novel equilibrium between trimer and dimer was evident in benzene solution. Thermodynamic parameters for this equilibrium have been obtained from ¹H n.m.r. measurements taken over a range of temperatures.