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Piezochromism in nickel salicylaldoximato complexes: tuning crystal-field splitting with high pressure
journal contribution
posted on 2016-08-02, 09:11 authored by Peter J. Byrne, Patricia J. Richardson, John Chang, Anna KusmartsevaAnna Kusmartseva, David R. Allan, Anita C. Jones, Konstantin V. Kamenev, Peter A. Tasker, Simon ParsonsThe crystal structures of bis(3-fluoro-salicylaldoximato)nickel( II) and bis(3-methoxy-salicylaldoximato) nickel(II) have been determined at room temperature between ambient pressure and approximately 6 GPa. The principal effect of pressure is to reduce intermolecular contact distances. In the fluoro system molecules are stacked, and the Ni Ni distance decreases from 3.19 Å at ambient pressure to 2.82 Å at 5.4 GPa. These data are similar to those observed in bis(dimethylglyoximato) nickel(II) over a similar pressure range, though contrary to that system, and in spite of their structural similarity, the salicyloximato does not become conducting at high pressure. Ni-ligand distances also shorten, on average by 0.017 and 0.011 Å for the fluoro and methoxy complexes, respectively. Bond compression is small if the bond in question is directed towards an interstitial void. A band at 620 nm, which occurs in the visible spectrum of each derivative, can be assigned to a transition to an antibonding molecular orbital based on the metal 3d(x 2-y 2) orbital. Time-dependent density functional theory calculations show that the energy of this orbital is sensitive to pressure, increasing in energy as the Ni-ligand distances are compressed, and consequently increasing the energy of the transition. The resulting blueshift of the UV-visible band leads to piezochromism, and crystals of both complexes, which are green at ambient pressure, become red at 5 GPa.
Funding
We thank EPSRC for funding.
History
School
- Science
Department
- Physics
Published in
Chemistry - A European JournalVolume
18Issue
25Pages
7738 - 7748Citation
BYRNE, P. ... et al., 2012. Piezochromism in nickel salicylaldoximato complexes: tuning crystal-field splitting with high pressure. Chemistry: a European journal, 18 (25), pp.7738-7748.Publisher
© Wiley-VCHVersion
- VoR (Version of Record)
Publisher statement
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/Publication date
2012Notes
Closed access.ISSN
0947-6539eISSN
1521-3765Publisher version
Language
- en