Ion-molecule reactions in mixtures of trimethylaluminum and methylamines

The ion-molecule reactions of mixtures of trimethylaluminum and methylamines, to serve as a model system for group 13–15 semiconductor fabrication, were examined by using Fourier transform ion cyclotron resonance mass spectrometry. Sequential ion-molecule reactions leading to formation of multiple adduets were observed for each of the reactant mixtures investigated. Collision-induced dissociation was used to probe the adduct structures. There is evidence for hydrogen bonding between the amines and aluminum in most of the adducts studied. Rearrangement of the aluminum/nitrogen skeletons was not observed, although the aluminum/nitrogen bonds appear to be relatively strong, so that stable adducts can be formed. The monomethylamine and dimethylamine readily produce gas-phase neutral adducts with trimethylaluminum, which can be related to the basicities of the methylamines.