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Description
This dissertation details the syntheses and structures of novel main group metal nitrogen compounds which are accessed through reaction of stannylamines with anionic metal halides. A brief review of nitrogen compounds of the group 13 metals is presented in Chapter 1, focusing on their synthesis, structure, and application as precursors to nitride semiconductors. Chapter 2 focuses on the synthesis of unassociated μ₃-nitrogen compounds of gallium. Reaction of [GaCl₄]⁻ salts with (Me₃Sn)₃N afforded the novel salts (Me₄N)₂[(X₃Ga)₂NSnMe₃] and (Ph₄P)₂[(X₃Ga)₂NSnMe₃] (X = Cl, Br). These are the first reported species containing a Ga₂(μ₃-N)Sn core and were shown to decompose at 150 °C in the solid state with the release of Me₃SnCl. Reaction of (Me₄N)[GaCl₄] with Cl₃Ga⋅N(SnMe₃)₃ afforded (Me₄N)₃[(Cl₃Ga)₃N], the first reported molecule in which nitrogen is ligated solely by gallium atoms. Chapter 3 focuses on the synthesis and characterization of [(ClIn)₆(NSnMe₃)₅(μ-Cl)₃]⁻. This anion, with its In₆N₅ core, is the highest nuclearity indium-nitrogen cluster or cage compound yet characterized. Molecules with preformed indium-nitrogen bonds are of interest as low temperature precursors to indium nitride semiconductors. Metal-nitrogen clusters, which in a sense are small fragments of the bulk nitrides, could potentially act as nucleation sites in colloidal nanoparticle synthesis. Mass spectrometry and NMR data for [(ClIn)₆(NSnMe₃)₅(μ-Cl)₃]⁻ indicates some stability in solution while solid state reactions show decomposition at 150°C with the release of Me₃SnCl. Chapter 4 discusses the synthesis of μ₄-nitrogen compounds of gallium. Reaction of [MCl₄]⁻ salts with Cl₃M⋅N(SnMe₃)₃ afforded the anions [(Cl₃M)₂N(SnMe₃)₂]⁻ (M = Ga, In). These molecules join the small family of μ₄-nitrides of the p-block metals of which only 16 examples had been previously identified. Additionally [(Cl₃Ga)₂N(SnMe₃)₂]⁻ is the first species with a Ga₂NSn₂ core. Elimination of [Me₃SnX₂]⁻ (X = Cl, Br) from highly concentrated reactions of [GaCl₄]⁻ and (Me₃Sn)₃N was exploited to produce the polynuclear clusters, [(Cl₂GaNSnMe₃)₃(SnMe₂Cl)]²⁻ and [Ga₃(NSnMe₃)₃(SnMe₂MeBr₅]⁻. These clusters provide crystallographic evidence for methyl-halogen exchange in the [GaCl₄]⁻/(Me₃Sn)₃N system. Finally Chapter 5 discusses the application of methods described in chapters 2-4 to the synthesis of bismuth-nitrogen clusters. Reaction of [Bi₄Cl₉]³⁻ with (Me₃Sn)₃N afforded the anion [Bi₄(NSnMe₃)₄(μ-Cl)₆]²⁻ which has a Bi₄N₄ cubane core structure. This molecule is only the second such Bi₄N₄ cubane, and is the first example of a bismuth-nitrogen compound in which nitrogen is bonded only to metals. Appendix A details the structures of 7 previously unreported [Me₃SnX₂]⁻ (X = Cl, Br) salts characterized during the course of our research. Appendix B details the syntheses of metal halide salts used as reactants in this work.
