NOTIZEN: EPR- und ligandenfeld-spektroskopische Strukturuntersuchungen an Cu(II)-Verbindungen / Investigations with Respect to the Structure of Cu(II)-compounds by EPR and Ligand Field Spectroscopy

1975 ◽  
Vol 30 (11-12) ◽  
pp. 970-972 ◽  
Author(s):  
Claus Friebel
Keyword(s):  
Field Parameter ◽  
Ligand Field ◽  
Field Spectroscopy ◽  
Distorted Octahedral ◽  
Structural Details ◽  
Jahn Teller ◽  
Crystallographic Axes ◽  
Ligand Field Parameter

From EPR and ligand field parameter some significant structural details of Cu(II)-compounds can be determined to a notable accuracy: a) the symmetry (tetragonal or orhombic) of Jahn-Teller distorted octahedral Cu(II)-sites, and b) the ordering of Jahn-Teller coupled Cu(II)-polyhedra with respect to each other as well as to the crystallographic axes of the Cu(II)-compound under investigation.

scholarly journals The crystal structure of szenicsite, Cu3MoO4(OH)4

1998 ◽  
Vol 62 (04) ◽  
pp. 461-469 ◽  
Author(s):  
Peter C. Burns
Keyword(s):  
Crystal Structure ◽  
Goodness Of Fit ◽  
Direct Methods ◽  
Ligand Field ◽  
Area Detector ◽  
Vertex Sharing ◽  
Distorted Octahedral ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Least Squares Techniques

Abstract The crystal structure of szenicsite, Cu3MoO4(OH)4, orthorhombic, a = 8.5201(8), b = 12.545(1), c = 6.0794(6) Å, V = 649.8(2) Å3, space group Pnnm, Z = 4, has been solved by direct methods and refined by least-squares techniques to an agreement index (R) of 3.34% and a goodness-of-fit (S) of 1.11 for 686 unique observed [|F| ⩾ 4σF] reflections collected using graphite-monochromated Mo-Kα X-radiation and a CCD area detector. The structure contains three unique Cu2+ positions that are each coordinated by six anions in distorted octahedral arrangements; the distortions of the octahedra are due to the Jahn-Teller effect associated with a d 9 metal in an octahedral ligand-field. The single unique Mo6+ position is tetrahedrally coordinated by four O2− anions. The Cu2+ϕ6 (ϕ: unspecified ligand) octahedra share trans edges to form rutile-like chains, three of which join by the sharing of octahedral edges to form triple chains that are parallel to [001]. The MoO4 tetrahedra are linked to either side of the triple chain of Cu2+ϕ6 octahedra by the sharing of two vertices per tetrahedron, and the resulting chains are cross-linked through tetrahedral-octahedral vertex sharing to form a framework structure. The structure of szenicsite is closely related to that of antlerite, Cu3SO4(OH)4, which contains similar triple chains of edge-sharing Cu2+ϕ6 octahedra.

Magnetism, electronic spectra, and structure of transition metal alkoxides. I. methoxides and ethoxides of chromium(II), manganese(II), Iron(II), cobalt(II), nickel(II), copper(II), titanium(III), chromium(III), and iron(III)

1966 ◽  
Vol 19 (2) ◽  
pp. 207 ◽  
Author(s):  
RW Adams ◽  
E Bishop ◽  
RL Martin ◽  
G Winter
Keyword(s):  
Transition Metal ◽  
Spectral Data ◽  
Electronic Spectra ◽  
Magnetic Moments ◽  
Field Parameter ◽  
Ligand Field ◽  
Metal Alkoxides ◽  
Infinite Lattices ◽  
Ligand Field Parameter

The magnetic moments and electronic spectra are reported for the following divalent transition metal methoxides: Cr(OCH3)2, Mn(OCH3)2, Fe(OCH3)2, Co(OCH3)2, Ni(OCH3)2, and Cu(OCH3)2. These measurements when coupled with the involatility and insolubility of the compounds favour structures based on infinite lattices composed either of regular (Mn, Fe, Co, and Ni) or distorted (Cr and Cu) MO6 octahedra. The spectral data place the ligand field parameter, Δ, for the methoxide group very close to that of water.

scholarly journals ESR-Untersuchungen zum Jahn-Teller-Effekt des Cu2+-Ions in oxidischen Perowskiten

1969 ◽  
Vol 24 (10) ◽  
pp. 1518-1525
Author(s):  
C. Friebel ◽  
D. Reinen
Keyword(s):  
Phase Transition ◽  
Tetragonal Phase ◽  
Esr Spectra ◽  
Ligand Field ◽  
X Ray ◽  
Field Spectroscopy ◽  
Jahn Teller ◽  
Low X ◽  
Ligand Field Parameters ◽  
Tetragonal Phase Transition

Abstract The ESR-powder-spectra of the perovskite-mixed-crystals M2II (CuxZn1-xW)O6 [MII=Sr, Ba] and Sr2(CuxZn1-xTe)O6 , which have been investigated by means of conventional X-ray-techniques and ligand-field-spectroscopy 1,2, are described and the results extensively discussed. The conclusions can be summarized as follows: (a) At very low x-values isolated, dynamically Jahn-Teller-distorted CuO6-octahedra are present in the cubic matrices, which can be frozen into tetragonally elongated polyhedra at 4.2 °K; (b) At high x-values the CuO6-entities are statically JT-distorted with the long axes lined up along the c-axis of the macroscopically tetragonal phases; (c) The ESR-spectra around the cubic-tetragonal phase-transition are complex, containing signals of obviously magnetically coupled Cu2+-ions; (d) The g-values "follow" the ligand-field-parameters quantitatively. Comparative data of some other compounds are given.

scholarly journals The Electrostatic Model for Calculation of the Ligand Field Parameter of Octahedral Complexes.

1956 ◽  
Vol 10 ◽  
pp. 1501-1503 ◽  
Author(s):  
Ole Bostrup ◽  
Chr. Klixbüll Jørgensen ◽  
R. A. Cox ◽  
A. R. Peacocke
Keyword(s):  
Field Parameter ◽  
Ligand Field ◽  
Electrostatic Model ◽  
Ligand Field Parameter

Spektroskopische Untersuchungen zum Jahn-Teller-Effekt des Cu2+-Ions in Verbindungen vom Typ A2CuL6, II / Spectroscopic Investigations with Respect to the Jahn-Teller Effect of Cu(II) in Compounds of the Type A2CuL6, II

1974 ◽  
Vol 29 (9-10) ◽  
pp. 634-641 ◽  
Author(s):  
Claus Friebel
Keyword(s):  
Structure Determination ◽  
Qualitative Agreement ◽  
Spectroscopic Data ◽  
Ligand Field ◽  
Orthorhombic Distortion ◽  
X Ray ◽  
Bond Lengths ◽  
Field Spectroscopy ◽  
Jahn Teller ◽  
Jahn Teller Effect

By means of EPR and ligand field spectroscopy a refinement of the Ba2CuF6 structure within the [CuF4/2F2]2--layers consisting of axially elongated CuF6-octahedra, 2-dimensionally connected by corners in an antiferrodistortive order, is given. In qualitative agreement with a recent structure determination by X-ray analysis the spectroscopic data prove, that the equatorial planes of the coupled CuF6-polyhedra form an angle of 2 γ > 90° (corresponding to a disturbed type of antiferrodistortive order). In contrast to 2 γ= 101° found by the X-ray investigation, the spectroscopic results suggest 2 γ = 119 (± 1)°, the consequence of which is an elongation of the Cu—F bond lengths and a remarkable orthorhombic distortion of the CuF6-octahedra.

The Ground State in Tris(acetylacetonato)ruthenium(III) from Low-Temperature Single-Crystal Magnetic Properties

1998 ◽  
Vol 51 (3) ◽  
pp. 229 ◽  
Author(s):  
Philip A. Reynolds ◽  
Brian N. Figgis ◽  
Boujemaa Moubaraki ◽  
Keith S. Murray
Keyword(s):  
Ground State ◽  
Field Model ◽  
Ligand Field ◽  
Spin Orbit Coupling ◽  
Coupling Constant ◽  
Magnetic Exchange Interaction ◽  
Magnetic Exchange ◽  
Structural Details ◽  
Ligand Field Parameter ◽  
Good Agreement

The magnetic susceptibilities of tris(acetylacetonato)ruthenium(III) have been measured between 2·5 and 300 K along the a, b, c, and a* axis directions, together with the magnetizations along the same directions up to a magnetic field of 5 T. There is a small amount of magnetic exchange interaction apparent below 10 K, with Weiss constants up to –0·35 K and the magnetization is fitted with exchange integrals up to –0·38 K in magnitude. A pathway for magnetic exchange in terms of a pair of symmetry-related Ru(acac) rings lying parallel and close is obvious from the structure. The susceptibility results above 10 K have been interpreted in terms of a four-parameter ligand field model (CF1) operating on the ground 2T2g term of the d5 configuration. The t2g orbitals are found to be split by 475 cm-1 by a dominant trigonal symmetry component and then by –50 cm-1 by a subsidiary rhombic component. The single-electron spin-orbit coupling constant is 875 cm-1 and the orbital angular momentum reduction parameter is 0·7. The g-values deduced for the ground Kramers doublet are not in good agreement with those from e.s.r. experiments, but rather better agreement is found for closely allied ligand field parameter sets (CF2) which can fit the susceptibilities at particular temperatures but do not reproduce their temperature dependence well. Consideration of the variation of structural details with temperature indicate that, in fact, the CF2 sets may be more realistic.

EPR INVESTIGATIONS OF CuO-B2O3-PbO-Ag2O GLASSES

2009 ◽  
Vol 23 (05) ◽  
pp. 747-753
Author(s):  
VIOREL TIMAR ◽  
RALUCA CICEO-LUCÃCEL ◽  
OCTAVIA HULPUŞ ◽  
IOAN ARDELEAN
Keyword(s):  
Copper Content ◽  
Structural Modification ◽  
Magnetic Interactions ◽  
Paramagnetic Resonance ◽  
Distorted Octahedral ◽  
Structural Details ◽  
Paramagnetic Probes ◽  
Parallel Band ◽  
Electron Paramagnetic ◽  
Epr Experiments

Glasses of the x CuO · (100 - x)[3 B 2 O 3· 0.9 PbO · 0.1 Ag 2 O ] system, with 0.5 ≤ x ≤ 10 mol %, were prepared and investigated by means of electron paramagnetic resonance (EPR) measurements. Structural details of different diamagnetic vitreous systems may be revealed by the Cu 2+ ions, frequently used as paramagnetic probes in EPR experiments. The shape and the intensity of the recorded EPR lines are dependent on the CuO content. The EPR spectra are asymmetric, with characteristics for Cu 2+ (3d9) ions in axially-distorted octahedral symmetric sites. Due to the interaction of the unpaired electron spin (s = 1/2) with the nuclear one (I = 3/2) of Cu 2+ ions, the characteristic hyperfine structure (hfs) is visible for small concentrations of CuO in both spectra bands (parallel and perpendicular). The increasing of copper content in the samples generates the EPR absorption spectra modification, the hfs being resolved in the parallel band of the spectra in whole compositional range, while in the perpendicular band, hfs disappear for x > 3 mol %. This fact indicates the structural modification in Cu 2+ vicinity and possible magnetic interactions.

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