On the Electronic Structure of a Singly Ionized Cluster Composed of Closed Shell Atoms Or Molecules

1987 ◽  
pp. 667-673
Author(s):  
Hellmut Haberland
Keyword(s):  
Electronic Structure ◽  
Closed Shell

Redox Potential - (Electronic) Structure Relationships in 18- and 17-Electron Mononitrile (or Monocarbonyl) Diphosphine Complexes of Re and Fe

2001 ◽  
Vol 66 (1) ◽  
pp. 139-154 ◽  
Author(s):  
M. Fátima C. Guedes Da Silva ◽  
Luísa M. D. R. S. Martins ◽  
João J. R. Fraústo Da Silva ◽  
Armando J. L. Pombeiro
Keyword(s):  
Cyclic Voltammetry ◽  
Electronic Structure ◽  
Binding Sites ◽  
Closed Shell ◽  
Carbonyl Complexes ◽  
Metal Centre ◽  
Pt Electrode ◽  
Metal Site ◽  
Oxidation Potentials ◽  
First Time

The organonitrile or carbonyl complexes cis-[ReCl(RCN)(dppe)2] (1) (R = 4-Et2NC6H4 (1a), 4-MeOC6H4 (1b), 4-MeC6H4 (1c), C6H5 (1d), 4-FC6H4 (1e), 4-ClC6H4 (1f), 4-O2NC6H4 (1g), 4-ClC6H4CH2 (1h), t-Bu (1i); dppe = Ph2PCH2CH2PPh2), or cis-[ReCl(CO)(dppe)2] (2), as well as trans-[FeBr(RCN)(depe)2]BF4 (3) (R = 4-MeOC6H4 (3a), 4-MeC6H4 (3b), C6H5 (3c), 4-FC6H4 (3d), 4-O2NC6H4 (3e), Me (3f), Et (3g), 4-MeOC6H4CH2 (3h); depe = Et2PCH2CH2PEt2), novel trans-[FeBr(CO)(depe)2]BF4 (4) and trans-[FeBr2(depe)2] (5) undergo, as revealed by cyclic voltammetry at a Pt-electrode and in aprotic non-aqueous medium, two consecutive reversible or partly reversible one-electron oxidations assigned as ReI → ReII → ReIII or FeII → FeIII → FeIV. The corresponding values of the oxidation potentials IE1/2ox and IIE1/2ox (waves I and II, respectively) correlate with the Pickett's and Lever's electrochemical ligand and metal site parameters. This allows to estimate these parameters for the various nitrile ligands, depe and binding sites (for the first time for a FeIII/IV couple). The electrochemical ligand parameter show dependence on the "electron-richness" of the metal centre. The values of IE1/2ox for the ReI complexes provide some supporting for a curved overall relationship with the sum of Lever's electrochemical ligand parameter. The Pickett parametrization for closed-shell complexes is extended now also to 17-electron complexes, i.e. with the 15-electron ReII and FeIII centres in cis-{[ReCl(dppe)2]}+ and trans-{FeBr(depe)2}2+, respectively.

Gas-phase reaction of CeVO5+ cluster ions with C2H4: the reactivity of cluster bonded peroxides

2015 ◽  
Vol 44 (7) ◽  
pp. 3128-3135 ◽  
Author(s):  
Jia-Bi Ma ◽  
Jing-Heng Meng ◽  
Sheng-Gui He
Keyword(s):  
Electronic Structure ◽  
Gas Phase ◽  
Closed Shell ◽  
Cluster Ions ◽  
Phase Reaction ◽  
Gas Phase Reaction ◽  
Metal Oxide Clusters ◽  
Transition Metal Oxide Clusters ◽  
Hydrocarbon Molecules ◽  
First Time

The reactivity of the peroxide unit with hydrocarbon molecules on transition metal oxide clusters with a closed-shell electronic structure has been identified for the first time.

The Electronic Structure of Closed Shell Metallocenes in the Ground State and in the Cationic Hole-States

1982 ◽  
Vol 37 (10) ◽  
pp. 1193-1204 ◽  
Author(s):  
Michael C. Böhm
Keyword(s):  
Electronic Structure ◽  
Transition Metal ◽  
Transition Metal Complexes ◽  
Ground State ◽  
Function Method ◽  
Closed Shell ◽  
Wave Functions ◽  
Computational Framework ◽  
General Rules ◽  
Reorganization Energies

The electronic structure of tne closed shell metallocenes bis(π-cyclopentadienyl)magnesium (1), bisbenzene chromium (2), ferrocene (3) and cyclopentadienyl benzene manganese (4) has been studied in the ground state as well as in the low-lying cationic states. The computational framework is a semiempirical INDO Hamiltonian, the theoretical framework for the investigation of the cationic hole-states is the Green's function method. The calculated ionization energies are compared with the photoelectron (PE) spectra of the four closed shell metallocenes. The interrelation between theoretically determined reorganization energies and the localization properties of the orbital wave functions or the nature of the transition metal center is analyzed. General rules concerning the validity of Koopman's theorem in transition metal complexes are formulated.

Electronic Structure Calculations Using A Modified Thomas-Fermi Approximation

2011 ◽  
Vol 1370 ◽  
Author(s):  
Gregory C. Dente ◽  
Michael Tilton
Keyword(s):  
Electronic Structure ◽  
Energy Density ◽  
Kinetic Energy ◽  
Valence Electron ◽  
Closed Shell ◽  
Electronic Structure Calculations ◽  
Kinetic Energy Density ◽  
Group Iii ◽  
Thomas Fermi ◽  
Structure Calculations

ABSTRACTWe have recently developed an accurate and easily implemented approach to many-electron calculations, based on a modified Thomas-Fermi approximation. Specifically, we derived an electron density approximation, the first term of which is the Thomas-Fermi result, while the remaining terms substantially corrected the density near the nucleus. In a first application, we used the new density to accurately calculate the details of the self-consistent ion cores, as well as the ionization potentials for the outer s-orbital bound to the closed-shell ion core of the Group III, IV and V elements. Next, we demonstrated that the new density expression allows us to separate closed-shell core electron densities from valence electron densities. When we calculated the valence kinetic energy density, we showed that it separated into two terms: the first exactly cancelled the potential energy due to the ion core in the core region; the second was the residual kinetic energy density resulting from the envelopes of the valence electron orbitals. These features allowed us to write a functional for the total valence energy dependant only on the valence density. This equation provided the starting point for a large number of electronic structure calculations. Here, we used it to calculate the band structures of several Group IV and Group III-V semiconductors. We emphasize that this report only provides a summary; detailed derivations of all results are in Reference 5.

scholarly journals A new family of [IrCl5(NO)]-salts. Structural diversity tuned by aryl embraces

2014 ◽  
Vol 70 (a1) ◽  
pp. C649-C649
Author(s):  
Florencia Di Salvo ◽  
Ana Foi ◽  
Ricardo Baggio ◽  
Damian Bikiel ◽  
Fabio Doctorovich
Keyword(s):  
Electronic Structure ◽  
Structural Diversity ◽  
Closed Shell ◽  
Open Shell ◽  
Phosphonium Salts ◽  
Structural Behaviour ◽  
Interaction Domain ◽  
Theoretical Evaluation ◽  
New Family ◽  
Electronic Distribution

The interactions experimented by multiple phenyl or other aromatic groups in crystals have been described as ``embraces'' since 1995, when Dance and co-workers developed the embrace paradigm as an important and widespread tool of supramolecular chemistry. There are three main classes of Multiple Phenyl Embraces (MPE) depending on the total number of phenyl rings (Ph) located in the interaction domain: sextuple (6PE), quadruple (4PE), and double phenyl embrace (2PE) [1]. Recently, an accurate theoretical evaluation of the MPE motifs between PPh4+was presented by Novoa et al [2]. In our laboratory we demonstrated that by changing the counterion of the [IrCl5(NO)]-salts from K+to PPh4+, it was possible to stabilize an excited state of the metal complex anion. The electronic distribution of the IrNO moiety in K[IrCl5(NO)] can be depicted as the closed-shell electronic structure IrIII–NO+. However, in PPh4[IrCl5(NO)] an unprecedented electronic perturbation takes place favouring the open-shell electronic structure IrIv–NO* [3]. These results together with the interesting systematic studies on MPE, encouraged us to explore the synthesis of new phosphonium salts. In this work we report new phosphonium ions of the type Ph3PR+and five new Ph3PR[IrCl5(NO)] salts (R = aryl, methylaryl). Structural analyses of these compounds were done in the context of the multiple embraces motifs. For the new unsymmetrical [IrCl5(NO)]-salts, the supramolecular arrangements are different from the one observed for the PPh4+one. In the last one, the 4PE infinite chains run parallel to the columns described by the anions [3] and for the others, the presence of bulkier substituents give place to symmetries that favours other kinds of aryl embraces resulting in a side by side location of the anions. Finally, DFT calculations were performed to evaluate the theoretical concerns regarding the structural behaviour, as well as the electronic distribution along the family of compounds.

scholarly journals Evolution of the electronic structure in open-shell donor-acceptor organic semiconductors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhongxin Chen ◽  
Wenqiang Li ◽  
Md Abdus Sabuj ◽  
Yuan Li ◽  
Weiya Zhu ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Organic Semiconductors ◽  
High Performance ◽  
Closed Shell ◽  
Open Shell ◽  
Ground State Structure ◽  
Structure Property ◽  
System A ◽  
Diradical Character ◽  
Donor Acceptor

AbstractMost organic semiconductors have closed-shell electronic structures, however, studies have revealed open-shell character emanating from design paradigms such as narrowing the bandgap and controlling the quinoidal-aromatic resonance of the π-system. A fundamental challenge is understanding and identifying the molecular and electronic basis for the transition from a closed- to open-shell electronic structure and connecting the physicochemical properties with (opto)electronic functionality. Here, we report donor-acceptor organic semiconductors comprised of diketopyrrolopyrrole and naphthobisthiadiazole acceptors and various electron-rich donors commonly utilized in constructing high-performance organic semiconductors. Nuclear magnetic resonance, electron spin resonance, magnetic susceptibility measurements, single-crystal X-ray studies, and computational investigations connect the bandgap, π-extension, structural, and electronic features with the emergence of various degrees of diradical character. This work systematically demonstrates the widespread diradical character in the classical donor-acceptor organic semiconductors and provides distinctive insights into their ground state structure-property relationship.

Reactivities of singlet oxygen: open-shell or closed-shell?

2020 ◽  
Vol 22 (24) ◽  
pp. 13373-13377
Author(s):  
Zexing Qu
Keyword(s):  
Electronic Structure ◽  
Singlet Oxygen ◽  
Closed Shell ◽  
Open Shell

The electronic structure and the reactivity of singlet oxygen with respect to two typical reactions.

scholarly journals Four Resonance Structures Elucidate Double-Bond Isomerisation of a Biological Chromophore

2020 ◽  
Author(s):  
Evgeniy Gromov ◽  
Tatiana Domratcheva
Keyword(s):  
Electronic Structure ◽  
Double Bond ◽  
Protein Interactions ◽  
Fluorescent Proteins ◽  
Closed Shell ◽  
Photoactive Yellow Protein ◽  
Resonance Structures ◽  
Highly Sensitive ◽  
Photochemical Properties ◽  
High Level

Photoinduced double-bond isomerisation of the chromophore of photoactive yellow protein (PYP) is highly sensitive to chromophore-protein interactions. On the basis of high-level ab initio calculations, using the XMCQDPT2 method, we scrutinise the effect of the chromophore-protein hydrogen bonds on the photophysical and photochemical properties of the chromophore. We identify four resonance structures – two closed-shell and two biradicaloid – that elucidate the electronic structure of the ground and first excited states involved in the isomerisation process. Changing the relative energies of the resonance structures by hydrogen-bonding interactions tunes all photochemical properties of the chromophore in an interdependent manner. Our study sheds new light on the role of the chromophore electronic structure in tuning in photosensors and fluorescent proteins.

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