Lewis Acid−Base Studies of Triorganogallium Compounds with Organophosphines

The relative Lewis acidities of the series of triorganogallium compounds GaR 3 (R = Me, Et, CH 2 CMe 3, CH 2 SiMe 3, CH 2 CMe 2 Ph, C 6 H 2 Me 3 ) toward the common Lewis base HPPh 2 and the relative Lewis basicities of a series of organophosphines which incorporate an acidic hydrogen HPRR‘ (PRR‘ = PPh 2, P(C 6 H 11 ) 2, PEt 2, P(H)(C 6 H 11 )) toward the common Lewis acid Ga(CH 2 CMe 3 ) 3 have been investigated and compared. Cryoscopic molecular weight data permitted an evaluation of the equilibrium constant for the dissociation of each of the adducts. The 31 P NMR spectral data, which were consistent with the molecular weight data, were also used to study the relative rates of hydrocarbon elimination reactions to form (R 2 GaPRR‘) 2 .