Gas Electron Diffraction Study Of The Vapour Over Dimethylamine-Gallane Leading To An Improved Structure For Dimeric Dimethylamidogallane, [Me2ngah2](2): A Cautionary Tale

Dimethylamine-gallane is relatively slow to decompose in a closed system and vaporises at low temperature primarily as Me-2(H)N center dot GaH3 molecules which can be trapped in a solid Ar matrix and characterised by their IR spectrum. Under the conditions needed to secure a useful gas electron diffraction ( GED) pattern, however, the vapour was found to consist of dimeric dimethylamidogallane molecules, [Me2NGaH2](2), formed from the secondary amine adduct by elimination of H-2, and the most reliable structure for which has been determined. Salient structural parameters (r(hl) structure) were found to be: r(Ga - N) 202.6(2), r(Ga - H) 155.6(8), r(N - C) 148.0(3), r(C - H) 111.2(6) pm; Ga - N - Ga 90.7(1), C - N - C 109.3(5), N - C - H 109.9(10) and H - Ga - H 119.4(42)degrees.