City Research Online

Abstract

A series of normal and complex tin (II) carboxylates are prepared and fully characterised by infrared and Mossbauer spectroscopy, differential thermal analysis, thermogravimetric analysis ad chemical analyses. Crystal structure determinations are carried out on two of these compounds, viz. potassium [hydrogen-bis-(maleato)] – stannate (II)and tin (II) malonate. Noth structures show unusual features , the maleato complex has Sn in a trigonal pyramidal environment but contains two types of maleate ligands and the malonate has tin in a site intermediate between the common trigonal- and square- pyramidal environments.

The catalytic activity of the tin (II) carboxylates I s tested in a number of polymerisation systems and the results obtained compared with those achieved using known catalysts. In all cases, the tin (II) species performed well. Mechanisms for the polymerisation systems are postulated on the basis of analytical measurements on the systems. In the case of propylene oxide polymerisation, both crystalline and amorphous polymers are obtained via cationic and anionic mechanisms, respectively. In the polymerisation of trioxane, the reaction pathway is cationic. A study of the curing of a commercial silicone resin shows that the cure time is dependent on (1) the catalyst used, (2) its concentration and (3) temperature, but is independent of the solvent used.

The spectroscopic characterisation of a series of diorganotin (IV) oxycarbonates provides evidence that they adopt a polymeric structure and four membered Sn2O2 rings. The solid and gaseous thermal decomposition pathways determined. The final solid residue is normally a dark coloured powder whose major component is tin (IV) oxide.

For the SnFs:MoS2 system, the removal of the distortion effects of the tin (II) lone pair electrons is shown to occur via the donation of the %s electrons is shown to occur via the donation of the %s electrons into conduction bands. Similar results are obtained for the tin (II) Halide-tin (IV) sulphide systems.

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

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