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Catenanes: A molecular mechanics analysis of the (C 13 H 26 ) 2 Structure 13‐13 D2
Author(s) -
Lii JennHuei,
Allinger Norman L.,
Hu ChingHan,
Schaefer Henry F.
Publication year - 2016
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.24193
Subject(s) - van der waals force , torsion (gastropod) , molecule , chemistry , crystallography , catenane , ring (chemistry) , van der waals radius , computational chemistry , medicine , surgery , organic chemistry
Molecular mechanics (MM4) studies have been carried out on the catenane (C 13 H 26 ) 2 , specifically 13‐13D2. The structure obtained is in general agreement with second‐order perturbation theory. More importantly, the MM4 structure allows a breakdown of the energy of the molecule into its component classical parts. This allows an understanding of why the structure is so distorted, in terms of CC bonding and nonbonding interactions, van der Waals repulsion, CCC and CCH angle bending, torsional energies, stretch‐bend, torsion‐stretch, and bend–torsion–bend interactions. Clearly, the hole in 113‐membered ring is too small for the other ring to fit through comfortably. There are too many atoms trying to fit into the limited space at the same time, leading to large van der Waals repulsions. The rings distort in such a way as to enlarge this available space, and lower the total energy of the molecule. While the distortions are spread around the rings, one of the nominally tetrahedral CCC bond angles in each ring is opened to 147.9° by MM4 (146.8° by MP2). The stability of the compound is discussed in terms of the strain energy. © 2015 Wiley Periodicals, Inc.