ANGEL LUIS ESTEBAN and ERNESTO D~Ez. Can. J. Chem. 58,2340Chem. 58, (1980. The 'H nmr spectrum of tetrahydrothiophene has been analyzed. The best set of coupling values (Hz) is: ,JA -,JB = 2.18, 3Ji = 5.53, 3Jfi = 7.31, ' J i e = 6.80, 3J19B = 6.37, 4 J i = -0.32, 4J6 = 0.25, 4JXB = 0.26, 4Jj,B = -0.47(A and B refer toa-and P-protons and c and t denote respectively the same and opposite sides of the ring). The variances observed between the values of this set and those reported by Lozach et al., particularly the interchange of the 4Ji and 4J6 couplings, are discussed and it is concluded that our set is the one that reproduces the most fine details of the spectrum profile. The proposed set has been selected as being the most physically meaningful, from amongst 24 equally valid sets of couplings, on the basis of a better agreement with the 3JB and 4JAB values calculated from a Karplus relationship and from the INDO-FPT method respectively. In these calculations it was assumed that the molecule was interconverting rapidly (on the nmr time scale) between two puckered conformations with C , symmetry. A detailed discussion of the dependence of the couplings on the height of the pseudorotational barrier and on the temperature indicate that the minimum values of the potential energy correspond to these conformations. Dans ces calculs, on afait I'hypothkse que la molCcule subit rapidement une interconversion (a I'echelle du temps de la rmn) entre deux conformations gauches avec une symetrie C , . Une discussion detaillee de I'effet de la hauteur de la barrikre pseudo-rotationnelle et de la temperature sur les couplages, indique que les valeurs minima de I'tnergie potentielle correspondent a ces conformations.[Traduit par le journal]