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Hydrogen-Bond Acceptor Properties of Nitro-O Atoms : A Combined Crystallographic Database and Ab Initio Molecular Orbital Study

Allen, Frank H. ; Baalham, Christine A. ; Lommerse, Jos P.M. ; Raithby, Paul R. and Sparr, Emma LU (1997) In Acta Crystallographica Section B: Structural Science 53(6). p.1017-1024
Abstract

Crystallographic data for 620 C - nitro-O⋯H - N,O hydrogen bonds, involving 560 unique H atoms, have been investigated to the van der Waals limit of 2.62 Å. The overall mean nitro-O⋯H bond length is 2.30 (1) Å, which is much longer (weaker) than comparable hydrogen bonds involving >C=O acceptors in ketones, carboxylic acids and amides. The donor hydrogen prefers to approach the nitro-O atoms in the C - NO2 plane and there is an approximate 3:2 preference for hydrogen approach between the two nitro-O atoms, rather than between the C and O substituents. However, hydrogen approach between the two O acceptors is usually strongly asymmetric, the H atom being more closely associated with one of the O atoms: only 60 H atoms have... (More)

Crystallographic data for 620 C - nitro-O⋯H - N,O hydrogen bonds, involving 560 unique H atoms, have been investigated to the van der Waals limit of 2.62 Å. The overall mean nitro-O⋯H bond length is 2.30 (1) Å, which is much longer (weaker) than comparable hydrogen bonds involving >C=O acceptors in ketones, carboxylic acids and amides. The donor hydrogen prefers to approach the nitro-O atoms in the C - NO2 plane and there is an approximate 3:2 preference for hydrogen approach between the two nitro-O atoms, rather than between the C and O substituents. However, hydrogen approach between the two O acceptors is usually strongly asymmetric, the H atom being more closely associated with one of the O atoms: only 60 H atoms have both O⋯H distances ≤ 2.62 Å. The approach of hydrogen along putative O-atom lone-pair directions is clearly observed. Ab-initio-based molecular orbital calculations (6-31G** basis set level), using intermolecular perturbation theory (IMPT) applied to the nitromethane-methanol model dimer, agree with the experimental observations. IMPT calculations yield an attractive hydrogen-bond energy of ca -15 kJ mol-1, about half as strong as the >C=O⋯H bonds noted above.

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publishing date
type
Contribution to journal
publication status
published
in
Acta Crystallographica Section B: Structural Science
volume
53
issue
6
pages
8 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:0000872589
ISSN
0108-7681
DOI
10.1107/S0108768197010239
language
English
LU publication?
no
id
ae594e29-11fb-45dd-b23e-ce74e33c2415
date added to LUP
2023-12-07 14:49:48
date last changed
2023-12-08 10:30:29
@article{ae594e29-11fb-45dd-b23e-ce74e33c2415,
  abstract     = {{<p>Crystallographic data for 620 C - nitro-O⋯H - N,O hydrogen bonds, involving 560 unique H atoms, have been investigated to the van der Waals limit of 2.62 Å. The overall mean nitro-O⋯H bond length is 2.30 (1) Å, which is much longer (weaker) than comparable hydrogen bonds involving &gt;C=O acceptors in ketones, carboxylic acids and amides. The donor hydrogen prefers to approach the nitro-O atoms in the C - NO<sub>2</sub> plane and there is an approximate 3:2 preference for hydrogen approach between the two nitro-O atoms, rather than between the C and O substituents. However, hydrogen approach between the two O acceptors is usually strongly asymmetric, the H atom being more closely associated with one of the O atoms: only 60 H atoms have both O⋯H distances ≤ 2.62 Å. The approach of hydrogen along putative O-atom lone-pair directions is clearly observed. Ab-initio-based molecular orbital calculations (6-31G** basis set level), using intermolecular perturbation theory (IMPT) applied to the nitromethane-methanol model dimer, agree with the experimental observations. IMPT calculations yield an attractive hydrogen-bond energy of ca -15 kJ mol<sup>-1</sup>, about half as strong as the &gt;C=O⋯H bonds noted above.</p>}},
  author       = {{Allen, Frank H. and Baalham, Christine A. and Lommerse, Jos P.M. and Raithby, Paul R. and Sparr, Emma}},
  issn         = {{0108-7681}},
  language     = {{eng}},
  month        = {{12}},
  number       = {{6}},
  pages        = {{1017--1024}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Acta Crystallographica Section B: Structural Science}},
  title        = {{Hydrogen-Bond Acceptor Properties of Nitro-O Atoms : A Combined Crystallographic Database and <i>Ab Initio</i> Molecular Orbital Study}},
  url          = {{http://dx.doi.org/10.1107/S0108768197010239}},
  doi          = {{10.1107/S0108768197010239}},
  volume       = {{53}},
  year         = {{1997}},
}