A study on the thermal properties and the solid state pyrolysis of the Lewis acid/base adducts [X3M·N(SnMe3)3] (X = Cl, Br; M = Al, Ga, In) and [Cl2MeM·N(SnMe3)3] (M = Al, Ga) as molecular precursors for group 13 nitride materials

Abstract

The Lewis acid/base adducts [X₃M·N(SnMe₃)₃] (1–3: X = Cl, Br; M = Al, Ga, In) and [Cl₂MeM·N(SnMe₃)₃] (4: M = Al, 5: M = Ga) were studied as precursors for group 13 nitride materials. The compounds were prepared by the 1∶1 mole reaction of MX₃ and MCl₂Me with N(SnMe₃)₃ at room temperature in diethyl ether and crystallised from CH₂Cl₂ at −20 °C. As shown by thermal analysis and the analysis of the volatile by-products, the precursors of the type [X₃M·N(SnMe₃)₃] decompose between 100 and 350 °C predominantly in two steps via dehalostannylation by partly releasing Me₃SnCl. Polycrystalline powders of AlN, GaN and InN were obtained after prolonged pyrolysis under inert conditions (argon, and in vacuo) above 350 °C and were contaminated with metallic tin according to the X-ray powder diffraction patterns. The pyrolysis of the organometallic precursors [Cl₂MeM·N(SnMe₃)₃] (4, 5) yielded tin-free nitride materials at temperatures below 350 °C due to the parallel elimination of SnMe₄ and Me₃SnCl, as evidenced by X-ray powder diffraction, elemental analysis, NMR and IR spectroscopy of the products.