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Conformational Analysis of trans ‐2,11‐Dithia‐4e,5,6,7e,8,9‐hexahydro[3.3]paracyclophane Using VT‐NMR
Author(s) -
Yang YaChen,
Lin ChenHuei,
Lin LeeHuei,
Lin ShawTao
Publication year - 2012
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.201100514
Subject(s) - chemistry , conformational isomerism , chemical shift , crystallography , proton nmr , proton , molecule , stereochemistry , computational chemistry , organic chemistry , physics , quantum mechanics
The conformation of trans ‐2,11‐dithia‐4 e ,5,6,7 e ,8,9‐hexahydro[3.3]paracyclophanes ( 5 , t DTHHPCP) was investigated by using 1 H NMR analysis under variable‐temperature condition. Based on the dynamic 1 H NMR behavior along with a structure obtained from simulation using the MM2 method, it has been deduced that 5 occurs preferentially in conformer 5a in CD 2 Cl 2 solution, which the two sulfur atoms are situated as the chair form and cyclohexano unit as a distorted boat form. The energy barrier (ΔG‡) for the inversion of the bridge (‐CH 2 SCH 2 ‐) has been estimated to be 11.6 kcal mol ‐1 (600 MHz, Tc = ‐30 °C). The proton chemical shifts are assigned for the individual hydrogen according to the spectra obtained at ‐70 °C.