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Conformational energies and rotational barriers in 3‐methyl‐1‐butene and 1‐butene: An ab initio and molecular mechanics study
Author(s) -
Pettersson Ingrid,
Gundertofte Klaus
Publication year - 1991
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.540120708
Subject(s) - ab initio , isopropyl , butene , 2 butene , chemistry , 1 butene , computational chemistry , ab initio quantum chemistry methods , rotation (mathematics) , internal rotation , alkyl , molecule , organic chemistry , ethylene , geometry , catalysis , mathematics , mechanical engineering , engineering
The calculated result obtained with MM2(87) for the rotation of the isopropyl group in 3‐methyl‐1‐butene is not in agreement with experimental data. In order to reparametrize the C sp 2‐C sp 3‐C sp ‐C sp 3 torsional angle, 3‐methyl‐1‐butene and 1‐butene have been studied by molecular mechanics (MM2(87)) and ab initio (MP2/6‐31G* and MP3/6‐31G*) calculations. The reparametrization of the torsional angle gives calculated results from MM2(87) in agreement with experimental data and ab initio calculations for both 3‐methyl‐1‐butene and 1‐butene. The calculated barriers for the rotation of alkyl groups in alkylbenzenes are improved with these new parameters.