| New developments in the synthesis and structural characterization of framework carbon-nitride compounds such as the stoichiometric cyanides of beryllium, magnesium and boron are presented. Preliminary high-pressure experiments indicate that boron tricyanide can be used as a starting material for high-pressure synthesis of pure and crystalline boron-carbon-nitride with a graphite-like structure. Preparation and structures of pyridine-coordinated Lewis acid-base complexes of main group cyanides of beryllium, boron, and gallium are also presented. Additionally, crystalline, air-stable, oxide-free main-group metal cyanamide compounds, such as beryllium carbodiimide with composition BeCN 2 and the ternary lithium-aluminum cyanamide (LiAlC2N 4) analog, have been prepared as bulk powders. In particular, efforts to prepare 3-D BeCN2 as a potential direct bandgap semiconductor is presented. These new crystalline solids are promising precursors that may ultimately lead to novel phases with structures related to silicon nitride (Si3N4), diamond and graphite.; Rational chemical vapor deposition (CVD) precursor design and synthesis of Group III and IV hydrides is very useful toward the development of engineered materials with a wide range of technological applications. The utility of metal borohydrides (metal = aluminum, zirconium and hafnium), disilylcyanamide (H3Si-N=C=N-SiH3), and group IV heteronuclear hydrides, such as germylsilane (H3GeSiH3) and digermylsilane (H 3GeSiH2GeH3) toward the synthesis of potentially hard film coatings and group IV infrared optoelectronic semiconductors are presented. Additionally, syntheses of related hydrides have been developed, such as germylsilyl triflate (H3GeSiH2OSO2CF 3), which is a potentially useful precursor for the synthesis of heteronuclear group IV hydrides. Unimolecular CVD precursors such as these are excellent candidates for thin film synthesis due to the exclusive loss of hydrogen during the growth process. |
