The Chemistry of Diphenylphosphine Adducts of Tris(Neopentyl)-and Tris(Trimethylsilylmethyl)-Gallium and -Indium Including the Crystal and Molecular Structure of (Me3CCH2)3Ga.P(H)Ph2

The adducts Me3CCH23Ga.PHPh2 and Me3SiCH23Ga.PHPh2 have been prepared as crystalline solids at room temperature and characterized by cryoscopic molecular weight measurements in benzene solution and 1H NMR, 31P NMR and IR spectroscopic data. The molecular weight studies demonstrate that both adducts are extensively dissociated in solution and that GaCH2CMe33 is a stronger Lewis acid than GaCH2SiMe3. An X-ray structural study defined the nature of Me3CCH23Ga.PHPh2 in the solid state. The colorless crystal contains two discrete molecules in each unit cell. The compound crystallizes in the triclinic space group P1. The adduct has a relatively long G-P distance fo 2.6835A and the alpha-carbon atoms of the substituents on gallium and phosphorus are essentially but not perfectly eclipsed. The syntheses of Me3CCH23In.PHPh2 and Me3SiCH23In.PHPh2 were attempted but room temperature elimination reactions, which produced CMe4 and SiMe4, respectively, and the appropriate organoindium phosphides, precluded and isolation of adducts.