Some aspects of the chemistry of sulphur-hetrocycles and related compounds.

3-Substituted thietane 1-oxides have been investigated by proton, carbon-13, and lanthanide induced shift, magnetic resonance studies, and for the two isomers of 3-p-bromophenylthietane 1-oxide, by X-ray crystallography. It has been concluded that it is reasonable to interpret the physical properties of a solution of the cis-isomers in terms of the single conformer in which both substituents occupy equatorial positions, and those of the trans-isomers in terms of approximately equal amounts of both possible conformers. cis and trans-3-Methylthietane 1-oxide react with toluene-p- -sulphonyl isocyanate to give the thietane imides with epimerisation. In polar solvents the reaction involves prior equilibration of the sulphoxides, but in non-polar solvents this does not occur. Pentamethyl-1-phenylphosphetan 1-oxides react with toluene-p- -sulphonyl isocyanate to give the phosphetan imides with retention of configuration. The reaction has been shown to be first order in both reactants. Optically active acyclic phosphine oxides however react to give racemic phosphine imides. The first step of this reaction involves racemisation of the phosphine oxide. Kinetic studies have shown this process to be first order in phosphine oxide and second order in isocyanate. Investigations suggest that if a reaction involves putting a formal positive charge on sulphur in a thietane or its 1-oxide, and if there is a good nucleophile in solution, then nucleophilic attack will occur at the a-carbon and ring opened products will result. The photolysis and flash thermolysis of a series of 4?-electron cyclic sulphones have been investigated. These reactions are thought to involve an unsaturated sulphene which rearranges to give a series of cyclic sulphinate esters. In the thermolysis reaction these then fragment. A number of novel organo-platinum complexes have been prepared and their structures have been determined by n.m.r. and infrared spectroscopy. Attempts to generate stable sulphene-metal complexes by rearrangement of the above complexes induced by thermal, photochemical, and chemical means, have not been successful.