Doctor of Philosophy
Kim M. Baines
In this thesis, the potential utility of solid-state NMR spectroscopy to provide insights into the structure and bonding of organogermanium and tin compounds is examined. Germanium-73 is an extremely challenging nucleus to examine due to multiple unfavourable NMR properties. However, the great utility of silicon-29 NMR spectroscopy suggests that 73Ge could be a valuable tool for structural characterization.
Initial investigations focused on a series of simple organogermanes as benchmarks for future investigations. Compounds with known X-ray structures were used to determine an effective method for density functional theory calculations. That methodology was then further employed to propose structures for several less well characterized compounds.
73Ge NMR spectroscopy was used, in conjunction with 35Cl and 79Br NMR spectroscopy, to characterize the novel germanium(I) halides, GeCl and GeBr. As the monohalides are amorphous, glasslike compounds, methods for structural characterization are limited. Calculation of the NMR parameters for a series of model compounds was used to propose a structure.
35Cl NMR spectroscopy was explored as a potential source of indirect information about germanium. There appears to be a relationship between the oxidation state at germanium and the shape of the 35Cl NMR signal. Additionally, a correlation between the NMR parameters of germanium(II) chlorides and Ge–Cl bond lengths was established.
119Sn NMR spectroscopy is better developed than 73Ge or 35Cl NMR spectroscopy. However, it is often difficult to obtain a 119Sn signal in solution at moderate magnetic field. A series of cationic tin(II) cryptand complexes were examined in the solid state. The 119Sn NMR parameters were used to describe the structure of a compound for which X-ray quality single crystals could not be grown. Additionally, several ambiguities about the bonding of a second compound were resolved.
Hanson, Margaret A., "Structural Insights into Group 14 Compounds from Solid-State NMR Spectroscopy" (2012). Electronic Thesis and Dissertation Repository. 1032.