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

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 -20degreesC. 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 350degreesC 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 350degreesC 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 350degreesC 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.