Oxidative Addition Reactions of Low-Valent Gallium Compounds with Primary Phosphanes

Abstract

Oxidative addition reactions of (Dipp2NacNac)Ga with the primary silylphosphanes R2R'Si-PH2 in toluene led to the phospha-gallanes (Dipp2NacNac)GaH(PHSiR2R’); R=R’=Me (1), R=Me, R’=Thex (2), R=R’=iPr (3) and R=Ph, R’=tBu (4). The same reaction starting from the diphosphane iPr2Si(PH2)2 yields the digallane {(Dipp2NacNac)GaH(PH)}2(SiiPr2) (5 a). In contrast, reaction with the hypersilylphosphane resulted in the elimination of (Me3Si)3SiH and formation of the diphospha-gallane (Dipp2NacNac)Ga(PH2)(PHSi(SiMe3)3) (6). The primary organo-phosphane tBuPH2 shows a similar reaction behavior in toluene though both the di- and monophospha-gallanes (Dipp2NacNac)GaX(PHtBu) (7 a: X=PH2, 7 b: X=H) occur. In a row of used solvents, only pyridine led selective to the formation of 7 b thus we tested the influence of this solvent on the reaction of iPr2Si(PH2)2 with only one equivalent (Dipp2NacNac)Ga which yields the compound (Dipp2NacNac)GaH(PHSiiPr2PH2) (5 b). Additionally, a derivative of compound 3, (Dipp2NacNac)GaCl(PHSiiPr3) (8), with an Cl atom bond to gallium instead of a hydrogen was obtained by the reaction of (Dipp2NacNac)GaCl2 with iPr3SiPHLi.