III/V PRECURSORS WITH P-H OR AS-H BONDS - A LOW-TEMPERATURE ROUTE TO GALLIUM-ARSENIDE AND GALLIUM-PHOSPHIDE

The trimers [t-Bu2Ga(mu-EH2)]3 (E = P, As) have been prepared via the reaction of t-Bu3Ga with EH3 at low temperatures. The structure of [t-Bu2Ga(mu-PH2)]3 has been established by X-ray crystallography. These are the first mu-PH2 and mu-AsH2 derivatives of gallium to be reported. Both compounds react with H2O to give the hydroxygallium trimer [t-Bu2Ga(mu-OH)]3. The structure of [t-Bu2Ga(mu-PH2)]3 features a planar six-membered Ga3P3 ring. Crystal data for [t-Bu2Ga(mu-PH2)]3: C24H60Ga3P3, M(n) = 650.83, hexagonal, space group P6BAR2m (No. 189), a = 11.127 (4) angstrom, c = 16.506 (6) angstrom, V = 1769.7 (5) angstrom 3, Z = 3, D(calc) = 0.867 g cm-3, mu(Mo K-alpha) = 13.4 cm-1, 880 unique reflections measured over the range 3.0 less-than-or-equal-to 2-theta less-than-or-equal-to 55.0-degrees (theta-2-theta scan mode), 446 reflections with I > 3-sigma(I) used in the refinements to give R and R(w) = 0.064 and 0.075, respectively. Thermal decomposition studies in solution and in the solid state show that both compounds afford the corresponding III/V semiconductor material at a relatively low temperature. [t-Bu2Ga(mu-PH2)]3 produces GaP at 248-degrees-C in the solid state and at 110-degrees-C when heated in toluene solution. [t-Bu2Ga(mu-AsH2)]3 gives GaAs at 250-degrees-C in the solid state and slowly at room temperature in hexane but more rapidly at 110-degrees-C when heated in toluene solution. The products are polycrystalline, as shown by X-ray powder diffraction studies.