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Conformational properties of disulphide bridges. 1. CS Rotational potential in ethyl hydrodisulphide
Author(s) -
Görbitz Carl Henrik
Publication year - 1993
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610061104
Subject(s) - chemistry , ab initio , electronic correlation , force field (fiction) , computational chemistry , conformational isomerism , ab initio quantum chemistry methods , potential energy , torsion (gastropod) , crystallography , molecule , atomic physics , organic chemistry , medicine , physics , surgery , artificial intelligence , computer science
The potential for CS rotation in ethyl hydrodisulphide, CH 3 CH 2 SSH, has been studied with ab initio methods. All stationary point structures were fully optimized at the HF/6–31G* and MP2/6–31G* levels. MP2/6–31G* molecular geometries were used in subsequent single‐point energy calculations with several basis sets and including various amounts of electron correlation up to the MP4SDQ/6–311+G(2d,p) level of theory. Zero‐point vibrational energies and thermal corrections were calculated and used to obtain relative values for Δ H 0 and Δ H 298 . The stability order for the three energy minima is gauche − ⩾ gauche + < trans (positive disulphide chirality, CSSH torsion ≈ 89°). The results have implications for force field calculations on disulphide bridge conformations in peptides and proteins.