Jahn-Teller Effect in Hexahydroxocuprate(II) Complexes

1995 ◽  
Vol 60 (9) ◽  
pp. 1429-1434
Author(s):  
Martin Breza

Using semiempirical CNDO-UHF method the adiabatic potential surface of 2[Cu(OH)6]4- complexes is investigated. The values of vibration and vibronic constants for Eg - (a1g + eg) vibronic interaction attain extremal values for the optimal O-H distance. The Jahn-Teller distortion decreases with increasing O-H distance. The discrepancy between experimentally observed elongated bipyramid of [Cu(OH)6]4- in Ba2[Cu(OH)6] and the compressed one obtained by quantum-chemical calculation is explainable by hydrogen bonding of the axial hydroxyl group.

1998 ◽  
Vol 62 (1) ◽  
pp. 121-130 ◽  
Author(s):  
Kharisun ◽  
Max R. Taylor ◽  
D. J. M Bevan ◽  
Allan Pring

AbstractDuftite, PbCu(AsO4)(OH) is orthorhombic, space group P212121 with a = 7.768(1), b = 9. 211(1), c = 5.999(1) Å, Z = 4; the structure has been refined to R = 4.6% and Rw = 6.5% using 640 observed reflections [F> 2σ(F)]. The structure consists of chains of edge-sharing CuO6 ‘octahedra’, parallel to c; which are linked via AsO4 tetrahedra and Pb atoms in distorted square antiprismatic co-ordination to form a three dimensional network. The CuO6 ‘octahedra’ show Jahn-Teller distortion with the elongation running approximately along <627>. The hydrogen bonding network in the structure was characterized using bond valence calculations. ‘β-duftite’ is an intermediate in the duftite-conichalcite series, which has a modulated structure based on the intergrowth of the two structures in domains of approximately 50 Å. The origin of the modulation is thought to be associated with displacements in the oxygen lattice and is related to the orientation of the Jahn-Teller distortion of CuO6 ‘octahedra’. Approximately half of the strips show an elongation parallel to <627> while the other strips are elongated parallel to [010]. This ordering results in an increase in the b cell repeat compared to duftite and conichalcite.


1970 ◽  
Vol 48 (14) ◽  
pp. 1694-1707 ◽  
Author(s):  
M. Inoue ◽  
R. Sati ◽  
S. Wang

The low-lying states of R′ centers in LiF, KCl, and KBr have been calculated using the quasicontinuum model of F aggregate centers. It turns out that the ground state of the R′ center is of 3A2 symmetry rather than 1A1 or 1E symmetry, and that the first excited state of the R′ center to which the optical transition occurs from its ground state is an orbitally doubly degenerate state (3E). The absorption line shape for the transition 3A2 → 3E of the R′ center has also been discussed for these crystals. The reasons for the presence of common features in the R′ bands in LiF, KCl, and KBr are pointed out. A comparison of the calculated results with the experimental results shows that the R′ band is due to the transition from the ground state of the R′ center (F3− center) to its first excited state perturbed by the dynamic Jahn–Teller distortion.


2014 ◽  
Vol 70 (6) ◽  
pp. m222-m223
Author(s):  
Amani Direm ◽  
Wahiba Falek ◽  
Guillaume Pilet ◽  
Nourredine Benali-Cherif

The asymmetric unit of the title compound, [Cu(C2H8N2)2(H2O)2](C11H11N4O2S)2, contains one sulfamerazinate anion in a general position and one half-cation that is located on a center of inversion. The CuIIcation shows a strong Jahn–Teller distortion. It is coordinated by four N atoms of two ethylenediamine ligands in the basal plane and two O atoms at much longer distances in the axial positions in a bipyramidal coordination. In the crystal, the building blocks are connected by N—H...N, O—H...N, N—H...O and O—H...O hydrogen bonding into a two-dimensional network parallel to (001).


2014 ◽  
Vol 70 (a1) ◽  
pp. C179-C179
Author(s):  
Yuta Orii ◽  
Masaki Kobayashi ◽  
Yuki Nagai ◽  
Kohei Atsumi ◽  
Daichi Tazaki ◽  
...  

For about a decade, we have systematically investigated thermally-accessible lattice strain and local pseudo Jahn-Teller distortion of [CuL2]3[M(CN)6]2·4H2O (L = (1R, 2R)-cyclohexanediamine; M = Cr, Co, and Fe). In mononuclear Cu(II) complexes, (pseudo) Jahn-Teller effect plays an important role in flexible distortion of crystal structures especially Cu(II) coordination environment. Beside Jahn-Teller distortion, we have dealt with some factors for example, metal substitution as bimetallic assemblies, chirality of ligands, and H/D isotope effect to vary intermolecular interaction and crystal packing. According to the course work using variable temperature PXRD, we have found that anisotropy of crystal strain distortion did not corporate with Jahn-Teller distortion around local coordination environment because of the discrepancy of the crystallographic axes and molecular alignment. In order to elucidate the anisotropic control of lattice strain and Jahn-Teller distortion closely, we have employed transition metal oxide with orthogonal or layered structures to prepare composite materials with the chiral metal complexes for discussion of thermally-accessible PXRD changes and IR shift due to adsorption. At first, we have employed chiral one-dimensional zig-zag Cu-Cr bimetallic assemblies and their oxides prepared by burining. Based on variable temperature XRD patterns, a linear correlation (lnK = a/T + b) of K (=d(T)-d(0)/d(T)) values, where d(T) and d(0) are spacing of lattice plane (d = nλ/(2sinθ)) at T K and 0 K (extrapolated), respectively, and its deviation from ideal correlation indicates degree of anisotropic lattice distortion of the composite materials. For example, we could observe LiMnO2, typical material of lithium ion battery, was enhanced anisotropic lattice strain along the b axis or the (011) plane added by [CuL2(H2O)2](NO3)2 complexes. Which may prevent from breaking down regular crystal structures during charge-discharge of secondary battery.


2020 ◽  
Author(s):  
Marta L. Vidal ◽  
Michael Epshtein ◽  
Valeriu Scutelnic ◽  
Zheyue Yang ◽  
Tian Xue ◽  
...  

We report a theoretical investigation and elucidation of the x-ray absorption spectra of neutral benzene and of the benzene cation. The generation of the cation by multiphoton ultraviolet (UV) ionization as well as the measurement of<br>the carbon K-edge spectra of both species using a table-top high-harmonic generation (HHG) source are described in the companion experimental paper [M. Epshtein et al., J. Phys.<br>Chem. A., submitted. Available on ChemRxiv]. We show that the 1sC -> pi transition serves as a sensitive signature of the transient cation formation, as it occurs outside of the spectral window of the parent neutral species. Moreover, the presence<br>of the unpaired (spectator) electron in the pi-subshell of the cation and the high symmetry of the system result in significant differences relative to neutral benzene in the spectral features associated with the 1sC ->pi* transitions. High-level calculations using equation-of-motion coupled-cluster theory provide the interpretation of the experimental spectra and insight into the electronic structure of benzene and its cation.<br>The prominent split structure of the 1sC -> pi* band of the cation is attributed to the interplay between the coupling of the core -> pi* excitation with the unpaired electron<br>in the pi-subshell and the Jahn-Teller distortion. The calculations attribute most of<br>the splitting (~1-1.2 eV) to the spin coupling, which is visible already at the Franck-Condon structure, and estimate the additional splitting due to structural relaxation to<br>be around ~0.1-0.2 eV. These results suggest that x-ray absorption with increased resolution might be able to disentangle electronic and structural aspects of the Jahn-Teller<br>effect in benzene cation.<br>


2021 ◽  
Vol 490 ◽  
pp. 229519
Author(s):  
Renier Arabolla Rodríguez ◽  
Nelcy Della Santina Mohallem ◽  
Manuel Avila Santos ◽  
Demetrio A. Sena Costa ◽  
Luciano Andrey Montoro ◽  
...  

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