Pseudo-Jahn–Teller Distortion in Two-Dimensional Phosphorus: Origin of Black and Blue Phases of Phosphorene and Band Gap Modulation by Molecular Charge Transfer

2016 ◽  
Vol 7 (7) ◽  
pp. 1288-1297 ◽  
Author(s):  
Chandra Chowdhury ◽  
Sheik Jahiruddin ◽  
Ayan Datta
Keyword(s):  
Charge Transfer ◽  
Band Gap ◽  
Two Dimensional ◽  
Teller Distortion ◽  
Molecular Charge ◽  
Jahn Teller ◽  
Blue Phases ◽  
Band Gap Modulation ◽  
Jahn Teller Distortion

Structure of the clinopyroxene-type compound CaCuGe2O6 between 15 and 800 K

2005 ◽  
Vol 61 (4) ◽  
pp. 367-380 ◽  
Author(s):  
Günther J. Redhammer ◽  
Gerold Tippelt ◽  
Michael Merz ◽  
Georg Roth ◽  
Werner Treutmann ◽  
...  
Keyword(s):  
Phase Transition ◽  
Magnetic Susceptibility ◽  
Magnetic Phase ◽  
Metal Layer ◽  
Lattice Parameters ◽  
Zigzag Chain ◽  
Two Dimensional ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Jahn Teller Distortion

CaCuGe2O6 shows a strongly distorted clinopyroxene-type structure with P21/c symmetry at 298 K. The Cu2+ ion at the M1 site is coordinated by six O atoms forming an octahedron, which deviates significantly from ideal geometry. Individual M1 sites are connected via common edges to form an infinite zigzag chain parallel to the crystallographic c axis. The Ca2+ ion at M2 shows a sevenfold coordination. M2 sites are connected to the M1 chain via three common edges, thereby forming a metal layer within the bc plane. Besides the strong Jahn–Teller distortion of the Cu site, the structure of the title compound differs from `normal' clinopyroxenes by a distortion of alternate layers of Ge sites. While the Ge(A) site is fourfold coordinated by O atoms, forming infinite chains of corner-sharing chains parallel to the c axis, the Ge(B) site exhibits a fivefold coordination, thereby forming a true two-dimensional layer of edge-sharing GeO5 bipyramids. Decreasing the temperature causes a magnetic phase transition at 40 K, as monitored by a broad maximum in the magnetic susceptibility and by discontinuities in the lattice parameters. Increasing the temperature causes variations in bond lengths, edge lengths and bond angles. Most prominent is the increase of one bond length of the Ge(B) site and the increase of the tetrahedral bridging angle of the Ge(A) site. At 660 K a crystallographic phase transition is observed where the symmetry changes from P21/c to C2/c. The transition is accompanied by large changes in the lattice parameters which are indicative of distinct topological changes of several structural building units. The high-temperature C2/c structure is similar to that of the germanate clinopyroxene CaMgGe2O6.

Variation of the Jahn–Teller distortion with pressure in perovskite layers A2CuCl4. Influence on the charge-transfer band

2007 ◽  
Vol 244 (1) ◽  
pp. 156-161 ◽  
Author(s):  
F. Rodríguez ◽  
F. Aguado ◽  
R. Valiente ◽  
M. Hanfland ◽  
J. P. Itiè
Keyword(s):  
Charge Transfer ◽  
Charge Transfer Band ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Jahn Teller Distortion

Bis(N-ethylethylenediamine-κ2 N,N′)copper(II)–hexacyanocobaltate(III)–water (3/2/4): a two-dimensional ladder structure of a bimetallic assembly

2006 ◽  
Vol 62 (4) ◽  
pp. m750-m752 ◽  
Author(s):  
Takashiro Akitsu ◽  
Yasuaki Einaga
Keyword(s):  
Two Dimensional ◽  
Complex Ions ◽  
Ladder Structure ◽  
Teller Distortion ◽  
Bond Lengths ◽  
Self Assembling ◽  
Distorted Octahedral Coordination Geometry ◽  
Distorted Octahedral ◽  
Jahn Teller ◽  
Jahn Teller Distortion

The title compound, poly[[tetracyano-octa-μ-cyano-hexakis(N-ethylethylenediamine)tricopper(II)dicobaltate(III)] tetrahydrate], [Cu(C4H12N2)2]3[Co(CN)6]2·4H2O or {[Cu3Co2(CN)12(C4H12N2)6]·4H2O} n , was crystallized from an aqueous reaction mixture containing Cu(ClO4)2, N-ethylethylenediamine and K3[Co(CN)6] in a self-assembling process. The polymeric chains are extended through –CoIII–CN–CuII– linkages involving four or two cyanide ligands of the centrosymmetric [Co(CN)6]3− complex ions, forming a two-dimensional ladder structure. The CuII atoms, one of which also lies on an inversion centre, have a distorted octahedral coordination geometry, the degree of tetragonal Jahn–Teller distortion being T = 0.785 and 0.810 (T is the ratio of mean in-plane Cu—N bond lengths to axial Cu—N bond lengths). This local Jahn–Teller distortion results from the anisotropic features of this two-dimensional cyano-bridged structure.

scholarly journals Diaquabis(ethylenediamine-κ2N,N′)copper(II) bis(sulfamerazinate)

2014 ◽  
Vol 70 (6) ◽  
pp. m222-m223
Author(s):  
Amani Direm ◽  
Wahiba Falek ◽  
Guillaume Pilet ◽  
Nourredine Benali-Cherif
Keyword(s):  
Hydrogen Bonding ◽  
Title Compound ◽  
Basal Plane ◽  
Building Blocks ◽  
Two Dimensional ◽  
Asymmetric Unit ◽  
Teller Distortion ◽  
Dimensional Network ◽  
Jahn Teller ◽  
Jahn Teller Distortion

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).

The Interplay of Open-Shell Spin-Coupling and Jahn-Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

2020 ◽  
Author(s):  
Marta L. Vidal ◽  
Michael Epshtein ◽  
Valeriu Scutelnic ◽  
Zheyue Yang ◽  
Tian Xue ◽  
...  
Keyword(s):  
High Harmonic ◽  
Open Shell ◽  
Spin Coupling ◽  
High Symmetry ◽  
Teller Distortion ◽  
Spectral Window ◽  
X Ray ◽  
Jahn Teller ◽  
X Ray Absorption ◽  
Jahn Teller Distortion

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>

Jahn-Teller Effect in Hexahydroxocuprate(II) Complexes

1995 ◽  
Vol 60 (9) ◽  
pp. 1429-1434
Author(s):  
Martin Breza
Keyword(s):  
Hydrogen Bonding ◽  
Quantum Chemical ◽  
Potential Surface ◽  
Hydroxyl Group ◽  
Chemical Calculation ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Extremal Values ◽  
Jahn Teller Distortion

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.

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