Equimolar mixtures of Me3M (M=Al, Ga, In) with five silylamines, N(SiMe3)3, HN(SiMe3)2, MeN(SiMe3)2, Me2NSiMe3, and HN(Me)SiMe3, were prepared in benzene-d6 and toluene-d8 solutions and variable temperature 1H- and 13C-NMR spectroscopy was utilized to deduce the capacity of these systems to form stable complexes under varying degrees of amine silylation. Approximate values for the cone angles of the bound amines are extrapolated from NMR data and from literature trends. The 1,2-elimination reactions of MMe3 with HN(Me)SiMe3 at 90°C (120°C for the Ga analogue) afford mixtures in solution of cis- and trans-[Me2MN(Me)SiMe3]2 which crystallizes in the trans form. In solution, the dimers equilibrate to mixtures of cis and trans geometrical isomers. The trans isomer is the predominant isomer for all three analogues. The equilibration process follows reversible first-order kinetics for each dimer. The thermodynamic and kinetic parameters for the trans to cis equilibration have been determined and are discussed in terms of an intramolecular ring opening mechanism. The molecular structure of trans-[Me2InN(Me)SiMe3]2 has been determined by a single crystal X-ray diffraction study. The molecule is dimeric and lies on a crystallographic center of symmetry. © 1999 Elsevier Science S.A.