TRIMETHYLALUMINIUM - SCRAMBLING OF METHYL GROUPS IN DIMER AND EXCHANGE WITH TRIMETHYLGALLIUM

Interchange of methyl groups between the bridging and terminal positions of trimethylaluminium dimer and exchange of methyl groups between trimethyl- aluminium and trimethylgallium in cyclopentane have been re-examined, again by means of proton magnetic resonance spectroscopy. Dissociation of the dimer is confirmed as the rate- determining step in both cases, but the rate of dissociation is much greater in toluene than in cyclopentane. The evidence previously put forward for a cage effect limiting the rate of exchange with trimethylgallium in cyclopentane is refuted and a revised mechanism for exchange is suggested. © 1969, CSIRO. All rights reserved.