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Updated: Jun 4, 2026

Thermochemical Studies of Ni(II) and Zn(II) Ternary Complexes Using Ion Mobility-Mass Spectrometry
Published on: June 8, 2022
Hexakis(urea-κO)zinc(II) dinitrate at 110 and 250 K: uniaxial negative thermal expansion
1Bijvoet Center for Biomolecular Research, Crystal and Structural Chemistry, Faculty of Science, Utrecht University, The Netherlands.
Abstract:
The crystal structure of the title compound, [Zn{CO(NH(2))(2)}(6)](NO(3))(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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