Synthesis and characterization of aluminum-pnicogen, gallium-antimony, and indium-antimony compounds; thermolysis of single-source precursors to gallium and indium antimonide

Over the past decade, there has been considerable research interest in the chemistry of compounds that contain a direct bond between elements of group 13 and group 15. This interest stems from the potential use of such compounds as single-source precursors to 13-15 (III-V) semiconducting materials, since the current methods of production of these materials are plagued by safety issues. Despite the volume of research performed in this area, only a small subset has addressed the chemistry of aluminum in these systems, and essentially no studies have examined the incorporation of antimony as the pnicogen.; In an effort to explore these neglected areas, the work presented herein focuses first on the synthesis and characterization of several new aluminum-phosphorus and -arsenic potential precursor compounds containing the (trimethylsilyl)methyl and neo-pentyl ligands, such as the dimer [(Me₃SiCH ₂)₂AlAs(SiMe₃)₂]₂ ( 9). These studies were conducted in order to examine what effect these larger alkyl groups might have in the aluminum system, and resulted in the formation of dimeric compounds similar to those previously observed in gallium and indium chemistry. In addition, the synthesis of compounds containing, gallium-antimony and indium-antimony bonds has also been examined, and it has been found that in most cases, the chemistry of antimony in these systems parallels that of both phosphorus and arsenic. This has allowed for the preparation of several compounds containing novel structural features never before observed in the antimony system, such as the mixed-pnicogen compound $Et2GaAsSi\; Me32GaEt2SbSiMe32$ (21). This work has resulted in the synthesis and characterization of twenty-three new compounds, fifteen of which have been characterized in the solid state by means of single crystal X-ray crystallography. These new potential precursors have been prepared using three main methods: (1) simple Lewis acid-base adduct formation; (2) dehalosilylation; (3) lithium halide elimination.; The thermolysis of several of these new precursors has also been examined, and both gallium antimonide and indium antimonide have been produced through a β-hydride elimination pathway, with particle sizes of the resultant materials falling within the nanocrystalline regime. The high volatility of several of these compounds also suggests they might be useful for the deposition of thin films under CVD conditions, and preliminary studies of [Et₂GaSb(SiMe ₃)₂]₂ (17) seem to support this view.