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|Title: ||Piezochromism in nickel salicylaldoximato complexes: tuning crystal-field splitting with high pressure|
|Authors: ||Byrne, Peter J.|
Richardson, Patricia J.
Kusmartseva, Anna F.
Allan, David R.
Jones, Anita C.
Kamenev, Konstantin V.
Tasker, Peter A.
|Keywords: ||High-pressure chemistry|
|Issue Date: ||2012|
|Publisher: ||© Wiley-VCH|
|Citation: ||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.|
|Abstract: ||The 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.|
|Description: ||Closed access.|
|Sponsor: ||We thank EPSRC for funding.|
|Publisher Link: ||http://dx.doi.org/10.1002/chem.201200213|
|Appears in Collections:||Closed Access (Physics)|
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