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Intramolecular interactions in sterically crowded hydrocarbon molecules
Author(s) -
Meitei Oinam Romesh,
Heßelmann Andreas
Publication year - 2017
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.24908
Subject(s) - steric effects , intramolecular force , chemistry , chemical physics , molecule , computational chemistry , density functional theory , interaction energy , london dispersion force , hydrocarbon , stereochemistry , organic chemistry , van der waals force
A molecular fragmentation method has been used to analyze the intramolecular interactions in the three molecules coupled diamantane, hexaphenylethane, and all‐meta‐ tert ‐butyl substituted hexaphenylethane. The significance of these systems lies in the fact, that steric crowding effects enable a stabilization of the central carbon bond that possesses an extended length (1.6 to 1.7 Å) beyond conventional carbon‐carbon bonds due to the steric repulsion of the attached hydrocarbon groups. The total stability of these molecules therefore depends on a delicate balance between attractive interaction forces on the one hand and on repulsive forces on the other hand. We have quantified the different interaction energy contributions using symmetry‐adapted perturbation theory based on a density functional theory description of the monomers. It has been found that the attractive dispersion interactions increase more strongly with the level of crowding in the systems than the counteracting exchange interactions. This shows that steric crowding effects can have a significant impact on the structure and stability of large and branched molecules. © 2017 Wiley Periodicals, Inc.