The conformational equilibrium of N,N '-bis[(S)-1-phenylethyl]-thiourea and its solvent dependence, studied by NMR and CD spectra and by X-ray crystallography

摘要

Favoured conformations of N,N'-bis[(S)-1-phenylethyl]thiourea (1) have been predicted by empirical force-field calculations, and the corresponding rotational strengths for the important transitions in the near UV region have been calculated. Experimental studies by H-1 NMR, IR, UV, and CD spectroscopy have permitted the assignment of a conformation denoted E,Za to the conformer, which dominates in nonpolar solvents, while hydroxylic solvents were found to favour conformations of Z,Za type. The E,Za conformer is also predicted by force-field calculations to be the most stable one. [References: 56]