The adducts (Me,N),C:NH,AIX, (X = Me or Et), from (Me,N),C:NH + 3 (or more) AI,X6 in hexane, are monomeric in dilute benzene solution and are believed to have a structure co-ordinated through the imino-nitrogen. They lose XH when heated, forming [(Me,N),C:NAIX,J,. for which four-membered ring structures are suggested. Although the adduct (Me,N),C:NH,AICI, does not similarly afford [(Me2N),C:NAICI,], when heated, the latter can be prepared from (Me,N),C:NLi and AICI,.1.r. spectroscopic details are given for all these new compounds.Also discussed are the l H n.m.r. spectra of the alkylaluminium compounds and the mass spectra of (Me,N),C:NH,-AICI, and [(Me,N),C:NAlEt,],.1,1,3,3-TETRAMETHYLGUANIDINE (Me,N),C:NH (I) has three potential donor sites of two distinct types, vix., the two dimethylamino-nitrogens and one imino-nitrogen.The object of this study of its interaction with some aluminium compounds was to investigate whether incorporating other potential donor sites in a molecule containing the imino-group )C=NH affected the manner of its interaction with aluminium Lewis acids. In an earlier study using diphenylketimine Ph2C:NH, ad-