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Hexakis(urea-O)zinc(II) dinitrate at 110 and 250 K: uniaxial negative thermal expansion

Hexakis(urea-O)zinc(II) dinitrate at 110 and 250 K: uniaxial negative thermal expansion The crystal structure of the title compound, Zn{CO(NH2)2}6(NO3)2, has been determined at 110 and 250 K. The structure is stabilized by 12 individual hydrogen bonds, both intra- and intermolecular. Analysis of the thermal expansion tensor, based on unit cells determined over a temperature range of 180 K, shows uniaxial compression in the direction of the b axis during warming. The hydrogen bonds form layers perpendicular to this axis and these layers are connected by coordinative bonds parallel to the axis. As expected, the intermolecular hydrogen bonds expand during warming. Surprisingly, the coordinative bonds contract, accompanied by changes in the O-Zn-O angles. Overall, this behaviour can be described as an accordion-like effect. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Acta Crystallographica Section C: Crystal Structure Communications International Union of Crystallography

Hexakis(urea-O)zinc(II) dinitrate at 110 and 250 K: uniaxial negative thermal expansion

Hexakis(urea-O)zinc(II) dinitrate at 110 and 250 K: uniaxial negative thermal expansion


Abstract

The crystal structure of the title compound, Zn{CO(NH2)2}6(NO3)2, has been determined at 110 and 250 K. The structure is stabilized by 12 individual hydrogen bonds, both intra- and intermolecular. Analysis of the thermal expansion tensor, based on unit cells determined over a temperature range of 180 K, shows uniaxial compression in the direction of the b axis during warming. The hydrogen bonds form layers perpendicular to this axis and these layers are connected by coordinative bonds parallel to the axis. As expected, the intermolecular hydrogen bonds expand during warming. Surprisingly, the coordinative bonds contract, accompanied by changes in the O-Zn-O angles. Overall, this behaviour can be described as an accordion-like effect.

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References (19)

Publisher
International Union of Crystallography
Copyright
Copyright (c) 2011 International Union of Crystallography
ISSN
0108-2701
eISSN
1600-5759
DOI
10.1107/S0108270111000023
pmid
21285496
Publisher site
See Article on Publisher Site

Abstract

The crystal structure of the title compound, Zn{CO(NH2)2}6(NO3)2, has been determined at 110 and 250 K. The structure is stabilized by 12 individual hydrogen bonds, both intra- and intermolecular. Analysis of the thermal expansion tensor, based on unit cells determined over a temperature range of 180 K, shows uniaxial compression in the direction of the b axis during warming. The hydrogen bonds form layers perpendicular to this axis and these layers are connected by coordinative bonds parallel to the axis. As expected, the intermolecular hydrogen bonds expand during warming. Surprisingly, the coordinative bonds contract, accompanied by changes in the O-Zn-O angles. Overall, this behaviour can be described as an accordion-like effect.

Journal

Acta Crystallographica Section C: Crystal Structure CommunicationsInternational Union of Crystallography

Published: Jan 18, 2011

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