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Temperature Dependence of the Crystal Structure and g-Values of trans-Diaquabis(methoxyacetato)Copper(II): Evidence for a Thermal Equilibrium Between Complexes with Tetragonally Elongated and Compressed Geometries

Citation

Simmons, CJ and Stratemeier, H and Hitchman, MA and Reinen, D and Masters, VM and Riley, MJ, Temperature Dependence of the Crystal Structure and g-Values of trans-Diaquabis(methoxyacetato)Copper(II): Evidence for a Thermal Equilibrium Between Complexes with Tetragonally Elongated and Compressed Geometries, Inorganic Chemistry, 50, (11) pp. 4900-4916. ISSN 0020-1669 (2011) [Refereed Article]


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Copyright Statement

Copyright 2011 American Chemical Society

DOI: doi:10.1021/ic200554f

Abstract

The crystal structures of trans-diaquabis- (methoxyacetato)copper(II) and the isostructural nickel(II) complex have been determined over a wide temperature range. In conjunction with the reported behavior of the g-values, the structural data suggest that the copper(II) compound exhibits a thermal equilibrium between three structural forms, two having orthorhombically distorted, tetragonally elongated geometries but with the long and intermediate bonds to different atoms, and the third with a tetragonally compressed geometry. This is apparently the first reported example of a copper(II) complex undergoing an equilibrium between tetragonally elongated and compressed forms. The optical spectrum of single crystals of the copper(II) compound is used to obtain metalligand bonding parameters which yield the g-values of the compressed form of the complex and hence the proportions of the complex in each structural form at every temperature. When combined with estimates of the JahnTeller distortions of the different forms, the latter produce excellent agreement with the observed temperature dependence of the bond lengths. The behavior of an infrared combination band is consistent with such a thermal equilibrium, as is the temperature dependence of the thermal ellipsoid parameters and the XAFS. The potential surfaces of the different forms of the copper(II) complex have been calculated by a model based upon JahnTeller coupling. It is suggested that cooperative effects may cause the development of the population of tetragonally compressed complexes, and the crystal packing is consistent with this hypothesis, though the present model may oversimplify the diversity of structural forms present at high temperature.

Item Details

Item Type:Refereed Article
Keywords:temperature dependence, crystal structure, thermal equilibrium, copper complex
Research Division:Chemical Sciences
Research Group:Inorganic Chemistry
Research Field:Transition Metal Chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
Author:Stratemeier, H (Dr Horst Stratemeier)
Author:Hitchman, MA (Dr Michael Hitchman)
ID Code:78030
Year Published:2011
Web of Science® Times Cited:5
Deposited By:Chemistry
Deposited On:2012-06-12
Last Modified:2015-02-07
Downloads:0

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