New Pnictinogallanes [H2GaE(SiMe3)2]3 (E ) P, As)sFormation, Structural Characterization, and Thermal Decomposition to Afford Nanocrystalline GaP and GaAs

The new compounds [H2GaE(SiMe3)2]3 (E ) P (1), As (2)), the first authenticated examples of a phosphinogallane and an arsinogallane containing the GaH2 moiety, are prepared Via efficient dehydrosilylation from the respective combinations of H3Ga‚NMe3 and E(SiMe3)3 in diethyl ether or toluene. Compounds 1 and 2 are characterized by elemental analysis, NMR, IR, and mass spectrometry. Single-crystal X-ray structural studies show that the molecular structures of 1 and 2 feature a flattened six-member ring of alternating Ga and E centers. Both compounds are reasonably stable at -30 °C but spontaneously decompose at ambient temperatures, 2 noticeably faster than 1, with the evolution of HSiMe3, H2, and E(SiMe3)3. The pyrolysis of 1 yields nanocrystalline GaP while the pyrolysis of solids from decayed 2 results in nanocrystalline GaAs as determined from XRD studies. Under applied pyrolysis conditions, the thermally accelerated dehydrosilylation of the precursors is accompanied by a side-evolution of CH4 and retention of small quantities of amorphous Si/C phases.