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The proton magnetic resonance spectrum and the barrier to internal rotation for benzeneselenol in solution

1977; Elsevier BV; Volume: 66; Issue: 3 Linguagem: Inglês

10.1016/0022-2852(77)90303-4

1096-083X

William J. E. Parr, Ted Schaefer,

Advanced NMR Techniques and Applications

Abstract The analysis of the proton magnetic resonance spectrum of a 5 mole% solution of benzeneselenol in CCl4 at 305K yields −0.45 Hz for the spin-spin coupling over six bonds between the sidechain proton and the ring proton in the para position. Comparison with the analogous couplings in phenol and in benzenethiol suggests that it is transmitted via a σ-π mechanism. Solution of the hindered rotor problem and allowance for error in measurement entails a two-fold barrier to internal rotation of 0.35 ± 0.25 kcal/mole for benzeneselenol. It would be of interest to compare this value to the as yet unknown barrier in the gas phase.