Organoaluminium compounds. XIV. Evidence for association through unlike bridging groups

Abstract

Proton magnetic resonance spectroscopy has revealed the formation of Me₂AlXYAlMe₂ from Me₂AIX₂Me₂ and Me₂AlY₂AlMe₂, where X and Y are bridging groups. In the cases studied, X = Cl, Y = Me, Br, or PhCC; X = Br, Y = Ph, PhCC, or OPr¹; and X = PhCC, Y = Opr¹. The position of equilibrium varies widely from one case to another. Formation of Me₂AlXYAlMe₂ is rapid except when dimethylaluminium isopropoxide is one of the reactants. The variation with temperature of the spectra of methylaluminium sesquibromide, methylaluminium sesquichloride, and mixtures of the latter with dimethylaluminium chloride has been examined and interpreted in terms of facile dissociation of the double halogeno bridge with a low probability of reassociation by way of methyl bridges.