On the origin of internal rotation in ammonia borane

doi:10.1007/s00894-014-2272-y

On the origin of internal rotation in ammonia borane

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On the origin of internal rotation in ammonia borane

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Bibliographic description

punktacja MEiN [2014 A]: 25

title:	On the origin of internal rotation in ammonia borane
author:	Parafiniuk Monika, Mitoraj Mariusz
journal title:	Journal of Molecular Modeling
volume:	20
issue:	6
date of publication :	2014
article ID:	2272
ISSN:	1610-2940
eISSN:	0948-5023
DOI:	10.1007/s00894-014-2272-y
URL:	https://link.springer.com/content/pdf/10.1007%2Fs00894-014-2272-y.pdf
date accessed:	2018-07-12
language:	English
journal language:	English
abstract in English:	The internal rotation in ammonia borane (AB) was studied on the basis of natural orbitals for chemical valence (NOCV) and eigenvectors for Pauli repulsion (NOPR). We found that the total hyperconjugation stabilization (ca. 5kcalmol − 1 ), based on the charge transfer from the occupied σ (B – H) orbitals into the empty σ *(N – H), slightly favors the staggered conformation over the eclipsed one; however, the barrier to internal rotation in ammonia borane can be understood predominantly in a ‘ classical ’ way, as originating from the steric (Pauli) repulsion contributions (of the kinetic origin) that act solely between N – HandB – H bonds. Repulsion be- tween the lone pair of ammonia and the adjacent B – H bonds was found to be dominant in absolute terms; however, it does not determine the rotational barrier. Similar conclusions on the role of CH ↔ HC repulsion appeared to be valid for isoelectronic ethane.
keywords in English:	ammonia borane, hyperconjugation, steric repulsion
affiliation:	Wydział Chemii : Zakład Metod Obliczeniowych Chemii
type:	journal article
subtype:	academic paper