THE CHEMISTRY OF DIPHENYLPHOSPHINE ADDUCTS OF TRIS(NEOPENTYL) AND TRIS(TRIMETHYLSILYLMETHYL)GALLIUM AND TRIS(TRIMETHYLSILYLMETHYL)INDIUM INCLUDING THE CRYSTAL AND MOLECULAR-STRUCTURE OF (ME3CCH2)3GA.P(H)PH2

The adducts (Me3CCH2)3Ga·P(H)Ph2 and (Me3SiCH2)3Ga·P(H)Ph2 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 Ga(CH2CMe3)3 is a stronger Lewis acid than Ga(CH2SiMe3)3. An X-ray structural study defined the nature of (Me3CCH2)3Ga·P(H)Ph2 in the solid state. The colourless crystal contains two discrete molecules in each unit cell. The compound crystallizes in the triclinic space group P1 with unit cell dimensions of a = 9.564(8), b = 12.208(5), c = 12.946(9) Å, α = 100.00(5), β = 100.41(8), γ = 102.97(7)° and Dcalc = 1.10 g cm-3. The adduct has a relatively long GaP distance of 2.683(5) Å and the α-carbon atoms of the substituents on gallium and phosphorus are essentially but not perfectly eclipsed. The syntheses of (Me3CCH2)3In·P(H)Ph2 and (Me3SiCH2)3In·P(H)Ph2 were attempted but room temperature elimination reactions, which produced CMe4 and SiMe4, respectively, and the appropriate organoindium phosphides, precluded the isolation of adducts. Simple kinetic studies revealed that In(CH2CMe3)3-P(H)Ph2 eliminated CMe4 at 17°C significantly faster than In(CH2SiMe3)3-P(H)Ph2 produced SiMe4. © 1990.