Group III Organometallic Derivatives

A number of studies have been carried out which establish that tri-methylaluminum exists as a dimer (77) having the structure 78, 145)  

While this suggests that there should be two resonance signals observed in the PMR spectrum, one corresponding to the bridge methyl groups and the other to the terminal methyl groups, the initial investigation of the PMR 

The second mechanism, Eq. (15), proceeds through a partial dissociation in which one of the Al—C bonds is broken, followed by rotation about the other, resulting in exchange. 

The bridge-terminal exchange can be accounted for by this process, where k l pkl, i.e., the rate-determining step is the dissociation of D to SCM and the activation energy for the process must be the dissociation energy corresponding to the process D - 2 SCM. In order to also account for the reaction with Ga(CH3)3 and In(CH3)3 in cyclopentane and toluene 

Rate Constants for Bridge-Terminal Exchange in A12(CH3)6 and for Methyl Exchange between A12(CH3)6 and Ga(CH3)3 in Cyclopentane and Toluene Solutions0 

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