Several symmetrical 1,3,2dithiazoI-2-yl radicals have been examined that have in common nitrogen-containing substituents a t the 4-and 5-positions, namely 4,5-dicyano-l,3,2-dithiazol-2-yl, 1 "N, I-l,3,2-dithiazolo [4,5-61 pyrazin-2-yl and 1,3,2-dithiazoleo 14,541 quinoxalin-2-yl. The ESR spectrum of the 4,Sdicyano radical does not reveal any "N splittings from the cyanide groups; however, the pyrazine and the quinoxaline derivatives do have multi-lined well resolved spectra arising from substantial hypefine interactions with these nuclei. The interactions are sufficiently large to be observed in the powder spectra of the latter. The presence of proton hyperfine interactions shows that unpaired-electron spin density is delocalized over all the rings. It has been found that the radicals attached to pyrazine and quinoxaline can be incorporated into single crystals of naphthalene and phenazine, respectively.

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Multi-frequency relaxation studies combined with the 'two-step' and 'three-step' models for molecular motion have been applied to a range of anionic surfactant molecules. From the internal dynamic parameters (q and S) conclusions have been drawn about the dependence of surfactant molecular dynamics inside micelles on molecular structure, and two unusual conformations have been identified. Slow correlation time (2,) data have also been obtained for these compounds. Three deuteriated surfactant molecules were subjected to the 'three-step' model and data are presented showing how the dimensions of the non-spherical micelles vary with temperature. An ESR spin probe study has been carried out on the compounds giving probe rotational correlation times at various temperatures. Information on alkyl chain packing at or near the water/micelle interface can be obtained from the derived thermodynamic parameters.

A series of related dithiazolidin-2yl free radicals prepared from cyclic strained alkenes and tetrasulphur dinitride, and an attempt was made to relate the nitrogen and proton hyperfine coupling constants to the radical structures. The radical made from dimethoxybenzonorbornadiene was studied by ENDOR and it was found that isotopic substitution with "N gives well resolved ENDOR spectra; the TRIPLE measurements showed that the I4N coupling constants are positive whereas all the resolved proton coupling constants are negative.

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