Aminoalane dimers of the formula [R2AlN(CH2Ph)2]2, where R = Prn, Bun, and Bui, were synthesized by thermolysis of the corresponding 1:1 mixtures of the trialkylaluminum and dibenzylamine at 120 °C. The 1H and 13C NMR spectra of the series [R2AlN(CH2Ph)2]2, where R = Me (1), Et (2), Prn (3), Bun (4), and Bui (5), were fully assigned using a combination of 1-D and 2-D NMR techniques. This series was also characterized by electron impact (EI) mass spectrometry and fragmentation patterns are discussed. The single-crystal X-ray structural data of [Et2AlN(CH2Ph)2]2 and [Bu2nAlN(CH2Ph)2]2 were determined and the data compared with those of [Me2AlN(CH2Ph)2]2 to identify any structural trends in the series with respect to R. The structural data for these three compounds are also compared with data for [MeAlN(H)CH2Ph]2, [RAlN(CH2Ph)-μ-(CH2C6 H4)]2, and Me3Al· HN(CH2Ph)2. Finally, the molecular structure data of [Me2MN(CH2Ph)2]2 and Me3M·HN(CH2Ph)2, where M = Al, Ga and In, are discussed in terms of the influence of the Group 13 metal. © 2002 Elsevier Science Ltd. All rights reserved.