The study of liquid solution and solid phase systems: I. Reactions and thermodynamics of alkyl halides. II. Structures and energetics of group 13-15 compounds

Electronic structure methods are very powerful in that insight into a wide variety of systems and diverse chemical phenomena may be gained by their application. The diversity of electronic structure methods is manifest in this thesis. A variety of methods are used to compute a number of different properties for a variety of systems in the gas, solution, and solid phases. In Part I of this thesis, electronic structure methods were employed to study the reactions and thermodynamics of alkyl halides. Initially, a methodology appropriate to study such reactions was developed by the optimization of a DFT method. Once a suitable level of theory was established, it was applied to allyl chloride identity nucleophilic substitution reactions to investigate the effects of solvation and methylation on the gas phase reactions. Then, the information gleaned from these studies was used to obtain high-quality estimates for the enthalpies of formation of a series of alkyl fluorides, which have proven difficult to obtain experimentally. In Part II of this thesis, electronic structure methods are employed to study compounds containing Group 13 and Group 15 elements. The first study in this section is an investigation of the effects on pi-bonding and negative hyperconjugation of a series of compounds as a function of the number of amino groups and the changing Group 13 element. The remaining studies are investigations to gain insight into gallium nitride compounds. A series of GaN rods formed by stacking cyclotrigallazane rings are studied, and a comparison of their energetics as well as geometric and electronic structures to isoelectronic GeC rods is performed. Then, an investigation of GaN sheets in several distinct conformations, formed by adding concentric cyclotrigallazane rings about a central ring is performed. The energetics and geometric and electronic structures for these sheets are compared to a number of isoelectronic species, including SiC, GeC, SiSi, and GeGe, and a correlation between the energetics of these sheets and those of the rods is proposed.