Reactions between organogallium compounds and nitriles

The systems RCN–GaR3′(R = Me, Ph, or But; R′= Me or Et) and Cl3CCN–GaMe3 have been studied, and the new adducts PhCN,GaMe3; ButCN,GaMe3; MeCN,GaEt3; PhCN,GaEt3; and ButCN,GaEt3 prepared and characterised. All tend to dissociate into the components under reduced pressure, particularly when heated gently, but when heated in closed vessels MeCN,GaMe3 gives methane and polymers, PhCN,GaMe3 gives 2,4,6-triphenyltriazine Ph3C3N3, and PhCN,GaEt3 and ButCN,GaEt3 lose ethylene to form the azomethine derivatives (PhCH:N·GaEt2)2 and (ButCH:N·GaEt2)2, respectively. Features of the infrared spectra of these compounds are discussed, and when compared with those of their boron and aluminium analogues provide further evidence that the acceptor properties of organo-derivatives of Group III elements decrease in the sequence R3Al > R3Ga > R3B.