Interpreting and controlling the structures of six-coordinate copper(<scp>ii</scp>) centres – When is a compression really a compression?

Halcrow, Malcolm A.

doi:10.1039/b309242a

Cited by 131 publications

(173 citation statements)

References 124 publications

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“…1,2 The g and τ 2g octahedral vibrational modes lift the orbital degeneracy and lower the energy of the system (T g X( g +τ 2g ) JT coupling, T g ) 2 T 2g , 3 T 1g ). JT and vibronic couplings have usually been ignored in theoretical studies of the magnetic properties of room-temperature magnets, derived from Prussian blue analogues with M(CN) 6 as building blocks for oligonuclear complexes. 3,4 T g X( g +τ 2g ) JT coupling in complexes with π-bonding or -antibonding T g states is expected to be weaker than that in systems where d electrons occupy the σ-antibonding e g subshell (EX g JT coupling).…”

Section: Introductionmentioning

confidence: 99%

“…A prominent example is that of complexes of Cu II . [5][6][7] However, energies involved in the T g X( g +τ 2g ) JT interaction are comparable to spin-orbit coupling energies and, therefore, are expected to strongly modify the magnetic behavior.…”

Section: Introductionmentioning

confidence: 99%

“…Jahn-Teller coupling to trigonal modes is also used to reinterpret the anisotropy of magnetic susceptibilities and g tensors of [Fe(CN) 6 ] 3-, and the 3 T 1g ground-state splitting of [Mn(CN) 6 ] 3-, deduced from near-IR spectra. The implications of the pseudo Jahn-Teller coupling due to t 2g -e g orbital mixing via the trigonal modes (τ 2g ) and the effect of the dynamic Jahn-Teller coupling on the magnetic susceptibilities and g tensors of [Fe(CN) 6 ] 3-are also addressed. …”

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confidence: 99%

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DFT-Based Studies on the Jahn−Teller Effect in 3d Hexacyanometalates with Orbitally Degenerate Ground States

et al. 2007

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The topology of the ground-state potential energy surface of M(CN) 6 with orbitally degenerate 2 T 2g (M ) Ti III (t 2g 1 ), Fe III and Mn II (both low-spin t 2g 5 )) and 3 T 1g ground states (M ) V III (t 2g 2 ), Mn III and Cr II (both low-spin t 2g 4 )) has been studied with linear and quadratic Jahn-Teller coupling models in the five-dimensional space of the g and τ 2g octahedral vibrations (T g X( g +τ 2g ) Jahn-Teller coupling problem (T g ) 2 T 2g , 3 T 1g )). A procedure is proposed to give access to all vibronic coupling parameters from geometry optimization with density functional theory (DFT) and the energies of a restricted number of Slater determinants, derived from electron replacements within the t 2g 1,5 or t 2g 2,4 ground-state electronic configurations. The results show that coupling to the τ 2g bending mode is dominant and leads to a stabilization of D 3d structures (absolute minima on the ground-state potential energy surface) for all complexes considered, except for [Ti(CN) 6 ] 3-, where the minimum is of D 4h symmetry. The Jahn-Teller stabilization energies for the D 3d minima are found to increase in the order of increasing CN-M π back-donation (Ti III < V III < Mn III < Fe III < Mn II < Cr II ). With the angular overlap model and bonding parameters derived from angular distortions, which correspond to the stable D 3d minima, the effect of configuration interaction and spin-orbit coupling on the ground-state potential energy surface is explored. This approach is used to correlate Jahn-Teller distortion parameters with structures from X-ray diffraction data. Jahn-Teller coupling to trigonal modes is also used to reinterpret the anisotropy of magnetic susceptibilities and g tensors of [Fe(CN) 6 ] 3-, and the 3 T 1g ground-state splitting of [Mn(CN) 6 ] 3-, deduced from near-IR spectra. The implications of the pseudo Jahn-Teller coupling due to t 2g -e g orbital mixing via the trigonal modes (τ 2g ) and the effect of the dynamic Jahn-Teller coupling on the magnetic susceptibilities and g tensors of [Fe(CN) 6 ] 3-are also addressed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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DFT-Based Studies on the Jahn−Teller Effect in 3d Hexacyanometalates with Orbitally Degenerate Ground States

et al. 2007

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“…As well understood [21][22][23], the Cu II ion forms a large variety of six-coordinate complexes, and the symmetric octahedrally coordinated Cu II ion is subject to Jahn-Teller distortion. Even the non-symmetrically substituted Cu II ions or actual Cu II ions slightly deviated from regular polyhedrons, Cu II ions can exhibit pseudo Jahn-Teller distortion.…”

Section: Discussionmentioning

confidence: 99%

“…In general, six-coordinated Cu II complexes in O h symmetry are subject to a strong E x coupling described by wrapped Mexican hat potential energy surface [20][21][22][23][24]. Three energy minima correspond to the orientation of distorted octahedral coordination environment and the frequency of transition between energy minima of dynamic equilibrium.…”

Section: Introductionmentioning

confidence: 99%

Thermally-Accessible Lattice Strain and Local Pseudo Jahn-Teller Distortion in Various Dimensional CuII-MIII Bimetallic Cyanide-Bridged Assemblies

Akitsu¹,

Einaga²,

Yoza³

2008

TOICJ

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(3), were prepared and characterized structurally. Crystal structures were determined at 263 and 100 K for 1 and 2, while at 299 and 100 K for 3. Thermally-accessible lattice strain resulted in decreasing cell volume of 1.66, 1.06, and 4.1 % for 1-3, respectively. Large thermally-accessible structural change but small pseudo Jahn-Teller elongation at constant temperature could be found in both the long chain of the ladder structure for 3 and the monocuclear Cu II moieties for 1 and 2. In addition, novel mixing of ferromagnetic and antiferromagnetic interactions at low temperature was observed for 3. The correlations between dimensionality of cyanide-bridges and thermally-accessible structural changes distortion associated with Jahn-Teller distortion are also discussed by comparing with several known systems.

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Copper: Inorganic & Coordination ChemistryBased in part on the article Copper: Inorganic & Coordination Chemistry by Rebecca R. Conry & Kenneth D. Karlin which appeared in the Encyclopedia of Inorganic Chemistry, First Edition .

Conry

2005

Encyclopedia of Inorganic Chemistry

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Copper was one of the first metals used widely because the metal is fairly plentiful (among the 25 most abundant elements in the earth's crust) and can be found in its metallic state. In addition, the metal and its alloys have a number of beneficial qualities including ductility, malleability, strength, corrosion resistance, and high thermal and electrical conductivity, combined with an attractive appearance. Copper is also an essential trace nutrient for organisms ranging from bacteria to mammals. Copper exhibits a rich coordination chemistry with complexes known in oxidation states ranging from 0 to +4, although the +2 (cupric) and the +1 (cuprous) oxidation states are by far the most common, with +2 predominating. Compounds of copper have found extensive practical usage, including as catalysts in both homogeneous and heterogeneous reactions, as fungicides, pesticides, and wood preservatives, as pigments for paints and glasses, and in the so‐called high‐temperature superconductors. The coordination numbers and geometries of copper complexes vary with oxidation state. For the spherically symmetric d 10 Cu I ion, the common geometries are two‐coordinate linear, three‐coordinate trigonal planar, and four‐coordinate tetrahedral. Cu I compounds are diamagnetic and colorless, except where color results from charge‐transfer bands or a counterion; these complexes are often fairly readily oxidized to Cu II compounds. The d 9 Cu II ion is usually found in a tetragonal coordination environment, with four short equatorial bonds and another one or two longer axial bonds although complexes with other structures are known, including tetrahedral, square planar, and trigonal bipyramidal geometries. Most of the Cu II compounds are blue or green because of d–d absorptions in the 600 to 900‐nm region; exceptions generally also have charge‐transfer bands tailing into the visible, causing a red or brown appearance. Cu III complexes are typically square planar and diamagnetic.

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Interpreting and controlling the structures of six-coordinate copper(ii) centres – When is a compression really a compression?

Cited by 131 publications

References 124 publications

DFT-Based Studies on the Jahn−Teller Effect in 3d Hexacyanometalates with Orbitally Degenerate Ground States

DFT-Based Studies on the Jahn−Teller Effect in 3d Hexacyanometalates with Orbitally Degenerate Ground States

Thermally-Accessible Lattice Strain and Local Pseudo Jahn-Teller Distortion in Various Dimensional CuII-MIII Bimetallic Cyanide-Bridged Assemblies

Copper: Inorganic & Coordination ChemistryBased in part on the article Copper: Inorganic & Coordination Chemistry by Rebecca R. Conry & Kenneth D. Karlin which appeared in the Encyclopedia of Inorganic Chemistry, First Edition .

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