City Research Online

Abstract

X-ray diffraction and Moessbauer spectroscopy were used to study lone-pair effects in some tin(ll) materials. The crystal structure of seven tin(ll) complexes were determined viz. (Mathematical equations exclusive to the thesis, please refer to the thesis). In addition the crystal structure of calcium tin(ll) malonate was also attempted and the tin environment determined. The tin atoms in all cases are in distorted trigonal pyramidal environments except for (please refer to thesis), where the tin atoms are in square pyramidal environments. These two environments feature a stereocheraically active lone-pair of electrons which prevents the closer approach of atoms along the direction in which the orbital points and are the most common configurations found in tin(ll) chemistry and this was verified by a survey undertaken of the most recent tin(ll) structures published in the literature.

A review of the tin-tin distances in all the known tin(ll) crystal structures showed that a short distance between two tin atoms could arise from the presence of bridging groups bringing the two tin atoms closer together or as result of the interaction of lone-pair orbitals pointing toward empty orbitals on adjacent tin atoms.

Thiourea complexes of some tin(ll) compounds were prepared and analysed by infrared spectroscopy, x-ray powder diffraction and Moessbauer spectroscopy. The Moessbauer spectra showed quadrupole splitting in all cases but for the complex (please refer to thesis). This is in contrast to earlier reported results that the complexes possessed no splitting. The thermal decomposition of the complexes were studied by simultaneous DTA and TG analysis, gas-cell infrared spectroscopy, mass spectroscopy and x-ray powder diffractometry and showed two patterns of results. The thiourea complexes with tin(ll) carboxylates decomposed to produce SnO as the main component, whilst in all other cases (please refer to thesis) was produced. The main gaseous products of thermal decomposition were (please refer to thesis) in all cases.

Publication Type:	Thesis (Masters)
Subjects:	Q Science Q Science > QD Chemistry
Departments:	School of Science & Technology School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

Export

Downloads