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Inventing new words and phrases is an indispensable means of capturing new concepts that arise as science advances. Some comparisons are made between the approaches of the nineteenth century natural philosopher Michael Faraday and the twentieth century spectroscopist Christian Klixbüll Jørgensen in their approach to naming new phenomena.
The present work focuses on the treatment of electron-electron repulsion which is part of the interpretation (analysis) of electronic spectra of transition group complexes using ligand field theory or the angular overlap model. Relative values of parameters which represent the strength of the d-d electron interaction in these models are considered, in particular the change of these parameters due...
Since the introduction of the Angular overlap model (AOM) in the mid-1960s, expressing d orbital energies in terms of the σ- and π-antibonding parameters eσ and eπ, the AOM has failed to supplant crystal field theory as the standard model to explain structure and electronic spectra in transition metal complexes. This is so despite the much more obvious connection in the AOM between structure...
The near-infrared to visible photon upconversion properties of Ti2+ and Ni2+ doped chloride and bromide lattices are summarized and discussed. They are used to illustrate the young and emerging field of transition metal based upconversion systems. It is demonstrated that transition metal upconversion properties can be tuned by chemical and structural variation. The change from NaCl to MgCl2 as a host...
Copper(II) complexes of N,N’-alkyl-bis(ethyl-2-amino-1-cyclopentenecarbodithioate) [alkyl=ethyl (L2), propyl (L3), and butyl(L4)] ligands have been synthesized and characterized. Analytical data for all three complexes show 1:1 copper-ligand stoichiometry. Well-resolved EPR spectra were recorded in toluene, benzene, and methylene chloride solutions at room temperature and in glassy toluene or toluene-methylene...
The optical and photophysical properties of three classic transition metal complexes, namely [Fe(bpy)3]2+, [Ru(bpy)3]2+ and [Co(bpy)3]2+, can be fine-tuned by doping them into a variety of inert host lattices. The effects of the guest-host interactions are discussed in terms of a chemical pressure. In this chapter we show how this chemical pressure can accelerate the high-spin→low-spin relaxation...
A general and user-oriented ligand field (LF) theory – LFDFT with parameters adjusted to DFT energies of separate Slater Determinants (SD) of the partly filled dn shell [n=2(8), 3(7), 4(6) and 5] of transition metals (TM) complexes – is developed and tested using 22 well documented examples from the literature. These include CrIII, d3 and CoII d7 in octahedral and CrIV, MnV, FeVI d2, CoII d7, MnII...
Changes undergone by optical and magnetic properties of Oh, Td and D4h Transition metal (TM) complexes induced by variations of the metal-ligand distance, R, are explored in this work. In parallel, the corresponding variations experienced by the chemical bonding in the complex are analysed in detail. Particular attention is addressed to TM complexes associated with impurities in insulating lattices...
The structures of all possible isomeric forms of the [M(η5-C5H5)(CO)2]2 complexes (M=Fe, Ru) are calculated with the use of the DFT method. The results indicate that both dimers can occur in three stable forms: bridged trans and cis and non-bridged trans. Contrary to the previous reports, the cis non-bridged form turns out to be an unstable transition state. Instead, an additional stable structure,...
We show how the introduction of the average one-center two-electron exchange integral, which is closely related to Jørgensens spin-pairing energy parameter, facilitates comparison of the Heisenberg-Dirac-van Vleck exchange parameter for different transition metal dimers. The formalism is illustrated on μ-oxo-dimanganese(III) and μ-oxo-dichromium(III) complexes in which the oxo bridge is the important...
The chemical bond in HArF is investigated with the help of the topological analysis of the electron density distribution and with an energy partitioning analysis. The results give quantitative insight into the nature of the interatomic interactions. The H-ArF bond is mainly covalent while the most important contributions to the argon-fluorine bond come from the electrostatic attraction between HAr...
This work reports the results of an investigation of the spectroscopic properties of trivalent praseodymium (Pr3+) in barium yttrium fluoride (BaY2F8). Two doping concentrations were used: BaY2F8:Pr3+ (0.3%) and BaY2F8:Pr3+ (1%). Absorption spectra, taken at 77 and 300 K, allowed the placement of the energy levels of the 4f2 electronic configuration of Pr3+. Luminescence spectra were obtained with...
The paper is devoted to the memory of my teacher and friend Christian K. Jørgensen who has written the pioneering works on complexes of Rare Earths (RE). The short theory of RE spectra and their transition probabilities and intensities, as well as the theory of energy transfer in the complexes of RE, is outlined. Europium cryptate was incorporated into zirconia glass and ormocer films. Europium sulfide...
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