Über die Natur der Cu2+-Zentren im NH4Cl - die spektroskopische Untersuchung von Cu2+-dotiertem Hg(NH3)2Cl2/The Nature of the Cu2+ Centres in NH4Cl - a Spectroscopic Investigation of Cu2+ Doped Hg(NH3)2Cl2

1992 ◽  
Vol 47 (4) ◽  
pp. 465-469 ◽  
Author(s):  
G. Steffen ◽  
U. Kaschuba ◽  
M. A. Hitchman ◽  
D. Reinen
Keyword(s):  
Ground State ◽  
Spectroscopic Investigation ◽  
Reflectance Spectra ◽  
Ligand Field ◽  
Field Reflectance

The preparation of Hg(NH3)2Cl2 doped with a small amount of Cu2+ is reported. The EPR and ligand field reflectance spectra indicate the presence of “CuCl4(NH3)2” polyhedra with a compressed tetragonal geometry and confirm, that the centres in Cu2+ doped NH4Cl possess the same geometry - as postulated earlier. The Cu2+ centres in Hg(NH3)2Cl2 are less compressed than those in NH4Cl, however, as could be deduced from the copper(II) hyperfine values, which are strongly influenced by the quite different admixture of the metal 4s orbital into the Alg (dz2) ground state in the two cases, and from the comparable energies of the d - d transitions.

Tieftemperatur-Remissionsspektren oktaedrisch koordinierter Cu2+ -Ionen im Ligandenfeldbereich / Low temperature reflectance spectra of octahedrally coordinated Cu2+-ions in solids

1973 ◽  
Vol 28 (3-4) ◽  
pp. 464-471 ◽  
Author(s):  
J. Grefer ◽  
D. Reinen
Keyword(s):  
Reflectance Spectra ◽  
Ligand Field ◽  
Teller Distortion ◽  
Square Planar ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Field Formalism ◽  
Field Reflectance ◽  
Host Lattices ◽  
Overlap Model

AbstractThe ligand field reflectance spectra of octahedrally coordinated Cu2+-ions in different host lattices and at different temperature (300 °K - 4 °K) are critically compared. Especially the band shifts with decreasing temperature are analysed with respect to transitions from a dynamical to a static Jahn-Teller effect (macroscopic Jahn -Teller distortion of the lattice). In addition the square planar coordination of Cu2+ is discussed and alternative descriptions in the crystal field formalism and the angular overlap model are given.

Spectroscopic investigation of ground state pyrrole (12C4H5N): the NH stretch

1997 ◽  
Vol 220 (3) ◽  
pp. 311-322 ◽  
Author(s):  
Abdeloihid Mellouki ◽  
Robert Georges ◽  
Michel Herman ◽  
Deanne L. Snavely ◽  
Svetlana Leytner
Keyword(s):  
Ground State ◽  
Spectroscopic Investigation

Fluorosulfates of palladium

1977 ◽  
Vol 55 (13) ◽  
pp. 2473-2477 ◽  
Author(s):  
K. C. Lee ◽  
F. Aubke
Keyword(s):  
Ground State ◽  
Diffuse Reflectance ◽  
Magnetic Measurements ◽  
Structural Information ◽  
Tridentate Ligand ◽  
Ligand Field ◽  
Polymeric Structure ◽  
Octahedral Environment ◽  
Fluorosulfate Group ◽  
Ligand Field Parameter

The syntheses of Pd(SO3F)2 and Pd(SO3F)3 by the reactions of palladium with BrOSO2F and S2O6F2 are described. Structural information on both compounds is based on infrared, Raman, diffuse reflectance, and electronic mull spectra as well as magnetic measurements from ∼300 to ∼100 K. Palladium bisfluorosulfate is found to have a polymeric structure with the fluorosulfate group acting as a tridentate ligand. As a consequence, an octahedral environment is found for Pd2+ with a 3A2g ground state, a µeff298 value of 3.39 BM and the ligand field parameter Dq = 1177 cm−1 and B = 633 cm−1. Pd(SO3F)3 is best regarded as PdII[PdIV(SO3F)6].

scholarly journals Ligand field parameters and the ground state of Fe(II) phthalocyanine

2013 ◽  
Vol 138 (24) ◽  
pp. 244308 ◽  
Author(s):  
M. D. Kuz'min ◽  
A. Savoyant ◽  
R. Hayn
Keyword(s):  
Ground State ◽  
Ligand Field ◽  
Ligand Field Parameters

A linear cobalt(II) complex with maximal orbital angular momentum from a non-Aufbau ground state

Science ◽  
2018 ◽  
Vol 362 (6421) ◽  
pp. eaat7319 ◽  
Author(s):  
Philip C. Bunting ◽  
Mihail Atanasov ◽  
Emil Damgaard-Møller ◽  
Mauro Perfetti ◽  
Iris Crassee ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Ground State ◽  
Dominant Role ◽  
Far Infrared ◽  
Wave Number ◽  
Ligand Field ◽  
Electron Configuration ◽  
Susceptibility Data

Orbital angular momentum is a prerequisite for magnetic anisotropy, although in transition metal complexes it is typically quenched by the ligand field. By reducing the basicity of the carbon donor atoms in a pair of alkyl ligands, we synthesized a cobalt(II) dialkyl complex, Co(C(SiMe2ONaph)3)2 (where Me is methyl and Naph is a naphthyl group), wherein the ligand field is sufficiently weak that interelectron repulsion and spin-orbit coupling play a dominant role in determining the electronic ground state. Assignment of a non-Aufbau (dx2–y2, dxy)3(dxz, dyz)3(dz2)1 electron configuration is supported by dc magnetic susceptibility data, experimental charge density maps, and ab initio calculations. Variable-field far-infrared spectroscopy and ac magnetic susceptibility measurements further reveal slow magnetic relaxation via a 450–wave number magnetic excited state.

scholarly journals Photoinduced Valence Tautomerism of a Cobalt-Dioxolene Complex Revealed with Femtosecond M-Edge XANES

2019 ◽  
Author(s):  
Ryan Ash ◽  
Kaili Zhang ◽  
Josh Vura-Weis
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
High Spin ◽  
Ground State ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
Ligand Field ◽  
Intersystem Crossing ◽  
Valence Tautomerism ◽  
Reduced Forms

Cobalt complexes that undergo charge-transfer induced spin-transitions (CTIST) or valence tautomerism (VT) from low spin (LS) Co(III) to high spin (HS) Co(II) are potential candidates for magneto-optical switches. We use M-edge XANES spectroscopy with 40 fs time resolution to measure the excited-state dynamics of Co(III)(Cat-N-SQ)(Cat-N-BQ), where Cat-N-BQ and Cat-N-SQ are the singly and doubly reduced forms of the 2-(2-hydroxy-3,5-di-tert-butylphenyl-imino)-4,6-di-tert-butylcyclohexa-3,5-dienone ligand. The extreme ultraviolet probe pulses, produced using a tabletop high-harmonic generation light source, measure 3p3d transitions and are sensitive to the spin and oxidation state of the Co center. Photoexcitation at 525 nm produces a low-spin Co(II) ligand-to-metal charge transfer state which undergoes intersystem crossing to high-spin Co(II) in 67 fs. Vibrational cooling from this hot HS Co(II) state competes on the hundreds-of-fs timescale with back-intersystem crossing to the ground state, with 60% of the population trapped in a cold HS Co(II) state for 24 ps. Ligand field multiplet simulations accurately reproduce the ground-state spectra and support the excited-state assignments. This work demonstrates the ability of M-edge XANES to measure ultrafast photophysics of molecular Co complexes.<br><br><br>

scholarly journals Design, Isolation, and Spectroscopic Analysis of a Tetravalent Terbium Complex

2019 ◽  
Author(s):  
Natalie Rice ◽  
Ivan Popov ◽  
Dominic Russo ◽  
John Bacsa ◽  
Enrique Batista ◽  
...  
Keyword(s):  
Ground State ◽  
Molecular Complexes ◽  
Lanthanide Ions ◽  
Ligand Field ◽  
Zero Field ◽  
High Symmetry ◽  
Zero Field Splitting ◽  
Terbium Complex ◽  
Field Splitting ◽  
Metal Ligand

Synthetic strategies to yield molecular complexes of high-valent lanthanides, other than the ubiquitous Ce<sup>4+</sup> ion, are exceptionally rare, and thorough, detailed characterization in these systems is limited by complex lifetime and reaction and isolation conditions. The synthesis of high-symmetry complexes in high purity with significant lifetimes in solution and solid-state are essential for determining the role of ligand-field splitting, multiconfigurational behavior, and covalency in governing the reactivity and physical properties of these potentially technologically transformative tetravalent ions. We report the synthesis and physical characterization of an <i>S</i><sub>4</sub> symmetric, four-coordinate tetravalent terbium complex, [Tb(NP(1,2-bis-<i><sup>t</sup></i>Bu-diamidoethane)(NEt<sub>2</sub>))<sub>4</sub>] (where Et is ethyl and <i>t</i>Bu is <i>tert</i>-butyl). The ligand field in this complex is weak and the metal-ligand bonds sufficiently covalent so that the tetravalent terbium ion is stable and accessible via a mild oxidant from the anionic, trivalent, terbium precursor, [(Et<sub>2</sub>O)K][Tb(NP(1,2-bis-<i><sup>t</sup></i>Bu-diamidoethane)(NEt<sub>2</sub>))<sub>4</sub>]. The significant stability of the tetravalent complex enables its thorough characterization. The step-wise development of the supporting ligand points to key ligand control elements for further extending the known tetravalent lanthanide ions in molecular complexes. Magnetic susceptibility, electron paramagnetic resonance (EPR) spectroscopy, X-ray absorption near-edge spectroscopy (XAS), and density functional theory studies indicate a <i>4f<sup>7</sup></i> ground state for [Tb(NP(1,2-bis-<i><sup>t</sup></i>Bu-diamidoethane)(NEt<sub>2</sub>))<sub>4</sub>] with considerable zero-field splitting: demonstrating that magnetic, tetravalent lanthanide ions engage in covalent metal-ligand bonds. This result has significant implications for the use of tetravalent lanthanide ions in magnetic applications since the observed zero-field splitting is intermediate between that observed for the trivalent lanthanides and for the transition metals. The similarity of the multiconfigurational behavior in the ground state of [Tb(NP(1,2-bis-<i><sup>t</sup></i>Bu-diamidoethane)(NEt<sub>2</sub>))<sub>4</sub>] (measured by Tb L<sub>3</sub>-edge XAS) to that observed in TbO<sub>2</sub> implicates ligand control of multiconfigurational behavior as a key component of the stability of the complex.

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