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Bay‐type H···H “bonding” in cis‐2‐butene and related species: QTAIM versus NBO description
Author(s) -
Weinhold Frank,
Schleyer Paul von Ragué,
McKee William Chadwick
Publication year - 2014
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.23654
Subject(s) - natural bond orbital , chemistry , steric effects , atoms in molecules , interpretation (philosophy) , crystallography , chemical physics , computational chemistry , molecule , density functional theory , stereochemistry , organic chemistry , philosophy , linguistics
We use comparative natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) methods to analyze the proximal bay‐type H···H interactions in cis‐2‐butene and related species, which lead to controversial interpretation as attractive “HH bonding” in the QTAIM framework. We address the challenging questions concerning well established structural, conformational, and vibrational properties of such species that appear to be sharply at odds with the QTAIM interpretation. In contrast to the purported “HH bonding” of QTAIM theory, NBO‐based evaluation of steric (donor–donor) and hyperconjugative (donor–acceptor) interactions unambiguously portrays such H···H contacts as dominated by steric clashes that are only partially softened by weak secondary hyperconjugative interactions, contributing negligibly ( b HH < 0.01) to H···H bond order. Additional details of NBO‐based versus QTAIM‐based description are provided by natural bond critical point analysis of topological bond critical point properties, which further emphasizes the contrast between the problematic bay‐type H···H contacts and remaining noncontroversial (consensus) chemical bonds. NBO analysis is thereby shown to be fully consistent with the traditional physical organic concept of repulsive bay‐type H···H contacts, including the corollary array of structural, conformational, and vibrational properties. © 2014 Wiley Periodicals, Inc.