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Electronic Configurations (electronic + configuration)
Selected AbstractsTitelbild: Two-Dimensional Triangular and Square Heterometallic Clusters: Influence of the Closed-Shell d10 Electronic Configuration (Angew. Chem.ANGEWANDTE CHEMIE, Issue 51 200951/2009) Vergoldete "Flöße" können aus Heterometallclustern entstehen. In der Zuschrift auf S.,9843,ff. beschreiben P. Braunstein, M. Bénard et,al. die Synthese, Struktur und theoretische Analyse einer einzigartigen Reihe zweidimensionaler Heterometall-Raft-Cluster der Art {M[m]}n (M=Cu, n=3; M=Ag, Au, n=4; der verbrückende Metalloligand [m] ist {MoCp(CO)3}). Intramolekulare, metallophile d10 -d10 -Wechselwirkungen treten sowohl in der ,2 -dreieckigen (M=Cu) als auch in den ,2 -quadratischen (M=Ag, Au) Strukturen der Metallkerne auf. [source] Two-Dimensional Triangular and Square Heterometallic Clusters: Influence of the Closed-Shell d10 Electronic Configuration,ANGEWANDTE CHEMIE, Issue 51 2009Sabrina Sculfort Handwerk mit goldenem Boden: Die Cluster {M[m]}n mit zweidimensionalem Kern (M=Cu, n=3; M=Ag oder Au, n=4; siehe Bild) und demselben verbrückenden Metalloligand [m]={CpMo(CO)3} wurden strukturanalytisch charakterisiert. Die ,2 -Dreiecks- (M=Cu) oder ,2 -Quadratstrukturen (M=Ag, Au) ihrer Kerne ermöglichen einen Vergleich der d10,,,d10 -Metall-Metall-Wechselwirkungen. Rechnungen deuten auf das Vorliegen diagonaler Au,,,Au- oder Ag,,,Ag-Wechselwirkungen hin. [source] Electronic Structures of KNa3In9 and Na2In, Two Metallic Phases with Classical Closed-Shell Electronic Configurations.CHEMINFORM, Issue 24 2006Bin Li Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] The Role of C,H···H,B Interactions in Establishing Rotamer Configurations in Metallabis(dicarbollide) SystemsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2010Emilio José Juárez-Pérez Abstract The aim of this work is to explore the self-interaction capability of the anion [3,3,-Co(1,2-C2B9H11)2], through Ccluster,H···H,B (Cc,H···H,B) dihydrogen bonds. A set of theoretical and empirical data aiming to establish the main rules that account for the binding mode between the negatively charged borane framework made by [3,3,-Co(1,2-C2B9H11)2], and the [NMe4]+ ions have been compiled. The interaction between cation and anion is mainly electrostatic but the covalent contribution is also proven and quantified. The existing intermolecular H···H short contacts have been studied and are compared with available data from the Cambridge Structural Database. The results show that the electronic configuration of the transition metal atom in the sandwich complex is not enough to define the preferred rotamer due to the influence of the anion environment and the H···H interactions present in the solid state. We present a methodology with widely used theoretical tools to study cation···cobaltabisdicarbollide interactions in the solid state. [source] Copper-Azide-Thioarylazoimidazoles , Structure, Spectra, Redox Properties, Magnetism and Theoretical InterpretationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2010Prasenjit Bhunia Abstract Azido-copper(II) and -copper(I) complexes of 1-alkyl-2-[(o -thioalkyl)phenylazo]imidazole (SRaaiNR,) have been prepared and studied. Complex 2 [Cu(SRaaiNR,)(,1,1 -N3)(N3)]2 dimerises via end-to-end (,1,3)-N3 to form a tetrameric structure. Azido-copper(I) complexes of the ligands are obtained as MeOH-bridged dimers, [Cu(SRaaiNR,)(N3)(,-OHMe)]2 (3). The electronic spectra suggest that a small reorganisation energy (0.08 eV) is associated with the change in electronic configuration, structure and oxidation state from CuII to CuI. Redox interconversion, CuII , CuI, [Cu(SMeaaiNMe)(,-N3)(N3)]2 (2a) , [Cu(SMeaaiNMe)(N3)(,-OHCH3)]2 (3a), has been performed in one case. The tetranuclear complex shows ferromagnetic and antiferromagnetic interactions. The spectra, redox chemistry and magnetism are explained by DFT studies. [source] Theoretical calculations of transition probabilities and oscillator strengths for Ti III and Ti IVINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2009Tian-Yi Zhang Abstract Due to the complicated electronic configuration of atoms and ions of the transition metal elements, the studies for properties such as transition probabilities and oscillator strengths for these atoms and ions are not systematic. Because of the existence in a variety of stellar objects and wide use in the field of astrophysics, titanium has long been of interest for many researchers. In this article within the Weakest Bound Electron Potential Model (WBEPM) theory, comprehensive set of calculations for transition probabilities and oscillator strengths for Ti III and Ti IV are performed. Many of our results had no previous experimental or theoretical values, so these predictive results could be of some value to the workers in this field. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Spin-dependent electron tunnelling and spin relaxation in quantum dots in regime with filling factor of around twoPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 8 2007S. Tarucha Abstract Spin-dependent electron tunnelling and spin relaxation were studied for a quantum dot in the regime with a filling factor between two and four. In this regime, the electronic configuration of a quantum dot undergoes transitions between a spin singlet and triplet states for an even number of electrons, and between two doublet states for an odd number of electrons. These transitions were clearly distinguished by using quantum wires as spin filtering contact leads to the dot. In addition, the temporal behaviour of electron tunnelling was studied for a quantum dot in a similar filling factor regime, using a quantum point contact as a charge sensor. Electron tunnelling through the dot in a spin singlet state could be well distinguished from that in a triplet state using the fact that the tunnelling rate was much larger for the triplet state. The difference in the tunnelling rate was also used to derive a triplet-to-singlet-state relaxation time. The obtained relaxation time agreed fairly well with that predicted by the theory of spin-orbit interaction. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spin-optimized resonating Hartree-Fock configuration interactionINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 15 2007Ryo Takeda Abstract The resonating Hartree-Fock Configuration Interaction (Res HF-CI) method is an efficient tool to investigate complicated strongly correlated systems such as ion-radical systems. In this method, we explore several spin-unrestricted Hartree-Fock (UHF) solutions that are energetically low-lying. However it is difficult to choose the symmetry-broken references appropriately as the site increases. In this study, we present the spin-optimized procedure, which is based on the Löwdin spin-projection method, for the Res HF-CI theory, denoted as SO Res-HF CI. We apply this SO Res-HF CI method to depict the potential curves of typical polyradical systems and compared the computational results using complete-active-space (CAS) CI based on UHF natural orbital (UNO), spin-projected UHF, and the previous version of Res HF-CI. We discuss the relation between computational results and the electronic configurations that are important to cover the electron correlation effects for each system. Further, we apply SO Res-HF CI method for the simple organic radical. In addition, we extend this scheme to the GHF case, and show that the use of GHF as a seed of SO Res-HF CI is desirable for the spin-frustrated systems. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source] Modeling dioxygen binding to the non-heme iron-containing enzymesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 10 2006A. V. Nemukhin Abstract The structures and properties of the complexes formed upon binding the oxygen molecule to the iron sites in non-heme 2-oxoglutarate-dependent enzymes are characterized by QM(CASSCF)/MM and density functional theory (DFT) calculations. Molecular models for the calculations are constructed following the crystal structure of hypoxia-inducible factor asparaginyl hydroxylase (FIH-1). DFT calculations for the 37-atomic cluster have been carried out at the B3LYP(LANL2DZdp) level. The flexible effective fragment potential method is used as a combined quantum mechanical,molecular mechanical (QM/MM) technique to characterize the fragment of the enzymatic system, including 1,758 atoms in the MM part and 27 atoms in the QM part. In these calculations, the CASSCF(LANL2DZdp) approach is applied in the QM subsystem, and AMBER force field parameters are used in the MM subsystem. With both approaches, equilibrium geometry configurations have been located for different spin states of the system. In DFT calculations, the order of the states is as follows: septet, triplet (+7.7 kcal/mol), quintet (+10.7 kcal/mol). Geometry configurations correspond to the end-on structures with no evidences of electron transfer from Fe(II) to molecular oxygen. In contrast, QM(CASSCF)/MM calculations predict the quintet state as the lowest one, while the septet structure has slightly (<2 kcal/mol) higher energy, and the triplet state is considerably more energetic. In QM/MM calculations, in both quintet and septet states, the electronic configurations show considerable electron charge transfer from iron to oxygen, and the oxidation state of iron in the metal binding site can be characterized as Fe(III). © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Nonadiabatic evolution of electronic states by electron nuclear dynamics theoryINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2005Frank Hagelberg Abstract The problem of how to determine the nonadiabatic content of any given dynamic process involving molecular motion is addressed in the context of Electron Nuclear Dynamics (END) theory. Specifically, it is proposed to cast the dynamic END wave function into the language of static electronic configurations with time dependent complex-valued amplitudes. This is achieved by adiabatic transport of an electronic basis along the classical nuclear trajectories of the studied molecular system, as yielded by END simulation. Projecting the dynamic wave function on this basis yields a natural distinction between adiabatic and nonadiabatic components of the motion considered. Tracing the evolution of the leading configurations is shown to be a helpful device for clarifying the physical nature of electronic excitation processes. For illustration of these concepts, dynamic configuration analysis is applied to the scattering of a proton by a lithium atom. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source] Experimental and theoretical transition probabilities in singly ionized goldMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007É. Biémont ABSTRACT Absolute transition probabilities have been measured for lines originating from the 5d96d and 5d97s electronic configurations in the spectrum of singly ionized gold (Au ii). The laser-induced breakdown spectroscopy has been applied to free gold atoms and ions produced by laser ablation. Absolute transition probabilities have been determined using the branching fraction and the Boltzmann plot methods. Theoretical branching fractions as well as radiative lifetime values have also been obtained by a relativistic Hartree,Fock method taking core polarization and configuration interaction effects into account. The new results are compared with previous results when available. [source] Quantum Chemical Study of the Reaction between Ni+ and H2SCHEMPHYSCHEM, Issue 14 2010Oier Lakuntza Abstract The reaction between the Ni+ cation and H2S is studied by considering both the doublet ground state and the lowest-lying quartet state. For the doublet state the reaction is endothermic, whereas it is exothermic for the quartet state. Both CCSD(T)//B3LYP and B3LYP levels of theory, combined with the triple-zeta quality TZVP++G(3df,2p), predict that there are three spin crossings along the characterized reaction path. The first one is located after the first transition state, and the second and third ones before and after the second transition state. On the quartet potential energy surface, both transition states are close in energy to the reactants, while on the doublet surface both lie quite higher in energy. The doublet and quartet states of the HNiSH+ four-membered intermediate lie very close in energy and their corresponding electronic configurations are connected by a single electron flip. This suggests that the -SH ligand would not prevent a facile intersystem crossing at this intermediate molecule, in contrast to the larger protection provided by the more electronegative OH ligand. [source] | |||||||||||||