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

Oxidative addition reactions of (Dipp(2)NacNac)Ga with the primary silylphosphanes R2R'Si-PH2 in toluene led to the phospha-gallanes (Dipp(2)NacNac)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 iPr(2)Si(PH2)(2) yields the digallane {(Dipp(2)NacNac)GaH(PH)}(2)(SiiPr(2)) (5 a). In contrast, reaction with the hypersilylphosphane resulted in the elimination of (Me3Si)(3)SiH and formation of the diphospha-gallane (Dipp(2)NacNac)Ga(PH2)(PHSi(SiMe3)(3)) (6). The primary organo-phosphane tBuPH(2) shows a similar reaction behavior in toluene though both the di- and monophospha-gallanes (Dipp(2)NacNac)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 iPr(2)Si(PH2)(2) with only one equivalent (Dipp(2)NacNac)Ga which yields the compound (Dipp(2)NacNac)GaH(PHSiiPr(2)PH(2)) (5 b). Additionally, a derivative of compound 3, (Dipp(2)NacNac)GaCl(PHSiiPr(3)) (8), with an Cl atom bond to gallium instead of a hydrogen was obtained by the reaction of (Dipp(2)NacNac)GaCl2 with iPr(3)SiPHLi.