A New Route To Tetra-Alkyltins And Some Novel Organostannate Complexes

This thesis is concerned with two aspects of organotin chemistry, namely the synthesis of organotin - compounds directly from free tin, and the formation of the organotin complexes known as organostannates. Initially, methods of forming tin-carbon bonds in single stage syntheses are reviewed. Subsequently, a reaction is described in which tin is reacted with alkyl halide in the presence of zinc and molten tetraalkylammonium iodide to produce tetraalkyltin and zinc chloride. The tetraalkyltin may be extracted from the mixture in yields of up to 34% on tin taken. Results are given for reaction of a number of organic halides. Chlorobenzene, which was the only aryl halide investigated, failed to react, while a series of alkyl chlorides containing branched alkyl groups underwent reaction, but failed to yield tetraalkyltin, the alkyl groups being lost from the reaction mixture as free radical rearrangement products. Much work was done on the reaction of butyl chloride to produce tetrabutyltin, a system which is of potential industrial importance. From the results of these studies, a mechanism has been proposed for the reaction, In addition to the work on the direct synthesis reaction, the chemistry, properties and applications of organostannate complexes are reviewed, and subsequently, the synthesis of twenty-two tetraalkylammonium di- and tri organohalogenostannate (IV) complexes is reported. Nineteen of these were new compounds. The Mossbauer spectra of these complexes have been studied, and the following definite structural assignments made on the basis of them: The pentacoordinate complexes had trigonal bipyramidal geometries, with in the case of the triorganostannates, axial halogens and equatorial organic groups, and in the case of the diorganostannates, axial halogens, and equatorial sites occupied by two organic groups and one halogen. The only hexacoordinate complexes which could be synthesised were diphenyltetra halogenostannates, and they had octahedral structures with trans axial phenyl -groups.