Complete analysis of the ¹H nmr spectrum of tetrahydrothiophene

Abstract

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]

Gold and Silver Chains from Tetrahydrothiophenocucurbit[6]uril as Au or Ag-Nanoparticles

“…The chemical difference between the two glycoluril faces results in magnetic nonequivalence for the ether CH 2 resonances, which occurred as two doublets at 5.25 and 4.96 ppm (J = 12 Hz), with the remaining CH 2 resonance of the tetrahydrothiopheno ring occurring as a singlet at 3.45 ppm. The chemical shift of the latter resonance was found to be ∼0.7−0.8 ppm downfield compared to tetrahydrothiophene; 22 however, the inclusion of sulfur was supported by HR-ESIMS with an ion at m/z 307.0475 for C 10 H 12 O 4 N 4 NaS.…”

Vibrational contributions to vicinal proton–proton coupling constants3JHH

“…It should be realized that for a methyl group the three rotational isomers are equivalent with equal populations of 1/3, therefore, equation (17) may be a reasonable approximation. On the other hand, when populations of rotational isomers are different, such as in the case of 1,2-disubstituted ethanes, the situation is much more complicated and the contributions from the torsional vibrations can be important [9][10][11][30][31]. The problem of the conformational analysis is then involved and the energy levels and wave functions for the appropriate Hamiltonian for hindered 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 The importance of vibrational contributions T vib J computed for the J couplings of near rigid molecules and methyl protons shows that these contributions must be inclu...…”