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

Simmons, Charles J., Stratemeier, Horst, Hitchman, Michael A., Reinen, Dirk, Masters, Vanessa M. and Riley, Mark J. (2011) 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: 4900-4916. doi:10.1021/ic200554f


Author Simmons, Charles J.
Stratemeier, Horst
Hitchman, Michael A.
Reinen, Dirk
Masters, Vanessa M.
Riley, Mark J.
Title 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
Journal name Inorganic Chemistry   Check publisher's open access policy
ISSN 0020-1669
1520-510X
Publication date 2011-06
Sub-type Article (original research)
DOI 10.1021/ic200554f
Volume 50
Issue 11
Start page 4900
End page 4916
Total pages 17
Place of publication Washington, DC, United States
Publisher American Chemical Society
Collection year 2012
Language eng
Formatted 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 metal-ligand 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 Jahn-Teller 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 Jahn-Teller 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.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
School of Chemistry and Molecular Biosciences
 
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Created: Thu, 13 Oct 2011, 15:02:12 EST by Mark J Riley on behalf of School of Chemistry & Molecular Biosciences