Date of Award
Chemistry and Biochemistry
Macdonald, Charles (Chemistry and Biochemistry)
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This thesis concerns the synthesis and study of the phenomenal ligand properties of crown ethers and glymes in stabilizing germanium and tin complexes in low oxidation states supported by either chlorides or triflates as the counter-anions. The abbreviated nomenclature for the ligands presented can be generalized by the form [x]crown-y, where [x] describes the total number of atoms and y, the total number of donor atoms of the ligand. Four differently-sized crown ethers, crown-4, crown-5, crown-6 and benzocrown-6 have been used in this dissertation. Crowned Ge(II) and Sn(II) complexes exhibit several unprecedented structural motifs that depend both on the size of the crown ether and the nature of the counter anions. Triglyme and tetraglyme have been used to stabilize Sn(II) complexes. The crowned Ge(II) molecules were characterized in the solid state by single crystal X-ray diffraction, NMR spectroscopy and IR spectroscopy. The Sn(II) complexes were characterized by a variety of methods including M÷ssbauer spectroscopy, Solid State NMR spectroscopy, and electrochemical studies. Extensive use of M÷ssbauer spectroscopy was also employed to gain insight into the s-character of the lone-pair on the tin centers. Subtle changes in ligands showed a pronounced effect on the symmetry of the complexes. To compare the results obtained from the observations and from experimental investigations, a series of density functional theory calculations are done on all the crowned Ge(II) and Sn(II) complexes in order to assess whether the structural features that are observed for the cationic fragments experimentally are consistent with the minimum energy structures in their gas phase.
RoyChowdhury, Rajoshree, "Stabilization of low-valent group 14 element" (2012). Electronic Theses and Dissertations. 397.