A conformational study of aromatic N-sulfinylamines

Electric dipole moments and PMR spectra of a series of substituted N-sulfinylanilines, Ar-N=S=O, indicate that these compounds adopt preferentially a cis or syn structure (Z-configuration) with respect to the central -N=S- bond. Direction and magnitude of the group moment of the NSO group are evaluated. From an analysis of the partial moments of the constituent atoms and groups, it appears that the lone pair of electrons in the non-bonding sp2 orbital of sulfur contributes 1.8-2.1 D to the total electric moment. In the light of the results obtained it seems likely that an analogous isomeric or rotameric form prevails in the corresponding aliphatic NSO compounds.