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1.
An information system for electronic spectra of transition elements called ESTE—DBS (DBS for data base system) has been described and discussed. This relational system is divided in two main parts, one containing data extracted from experimental spectra, the second created by simulation on the basis of the ligand field theory and some empirical parameters. 相似文献
2.
T. M. Ivanova A. G. Kochur A. V. Shchukarev R. V. Linko N. S. Terebova M. A. Kiskin A. A. Sidorov V. M. Novotortsev I. L. Eremenko 《Russian Journal of Inorganic Chemistry》2012,57(11):1484-1489
Binuclear pivalate complexes of 3d transition metals (manganese, iron, cobalt, and nickel) with the same ligand environment and a lantern structure have been studied by X-ray photoelectron spectroscopy. The M2p, M3s, C1s, O1s, and N1s X-ray photoelectron spectra have been examined. A redistribution of electron density in the OCO group has been revealed. It has been shown that the theory fits the experimental data on the energy separation between the high- and low-spin components in the M3s spectra and between the spin doublet components in the M2p spectra. It has been demonstrated that the iron, cobalt, and nickel complexes are paramagnetic at room temperature, whereas the manganese complex exhibits antiferromagnetic properties. There is a correlation between the size of the 3d subshell of the transition metal atom and the M-O and M-N bond lengths. 相似文献
3.
Daniel T. Mainz Jasna J. Klicic Richard A. Friesner Jean-Marc Langlois Jason K. Perry 《Journal of computational chemistry》1997,18(15):1863-1874
We have developed a parameterization enabling ab initio electronic structure calculation via the PS-GVB program on transition-metal-containing systems using two standard effective core potential basis sets. Results are compared with Gaussian-92 for a wide range of complexes, and superior performance is demonstrated with regard to computational efficiency for single-point energies and geometry optimization. Additionally, the initial guess strategy in PS-GVB is shown to provide considerably more reliable convergence to the ground state. © 1997 John Wiley & Sons, Inc. J Comput Chem 18 : 1863–1874, 1997 相似文献
4.
I. P. Romm A. A. Malkov S. A. Lebedev V. V. Levashova T. M. Buslaeva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(2):248-253
The electronic absorption spectra of palladium(II) diacetate (PDA) complexes with phosphines and sulfides (D) with the composition
Pd(OAc)2 · 2D (1: 2) contain an intense charge transfer band at λmax ∼ 300 nm (ɛ ∼ 15 000) and do not absorb in the region of 400 nm. Polynuclear compounds such as PDA trimer [Pd(OAc)2]3, trimer complexes with D, and four- and six-membered palladium metallocyclic compounds formed in the interaction of PDA with
mercaptans absorb at longer wavelengths. The electronic absorption spectra of all the palladium polynuclear compounds (clusters)
contain bands at λmax ∼ 400 nm (ɛ ∼ 1000). The appearance of these bands in the spectra of palladium clusters is evidence of the formation of chemical
bonds between neighboring Pd atoms, although Pd…Pd distances substantially exceed the sum of the covalent radii of palladium
atoms. 相似文献
5.
Inverted sandwich type complexes (ISTCs) of 4d metals, (μ-η(6):η(6)-C(6)H(6))[M(DDP)](2) (DDPH = 2-{(2,6-diisopropylphenyl)amino}-4-{(2,6-diisopropylphenyl)imino}pent-2-ene; M = Y, Zr, Nb, Mo, and Tc), were investigated with density functional theory (DFT) and MRMP2 methods, where a model ligand AIP (AIPH = (Z)-1-amino-3-imino-prop-1-ene) was mainly employed. When going to Nb (group V) from Y (group III) in the periodic table, the spin multiplicity of the ground state increases in the order singlet, triplet, and quintet for M = Y, Zr, and Nb, respectively, like 3d ISTCs reported recently. This is interpreted with orbital diagram and number of d electrons. However, the spin multiplicity decreases to either singlet or triplet in ISTC of Mo (group VI) and to triplet in ISTC of Tc (group VII), where MRMP2 method is employed because the DFT method is not useful here. These spin multiplicities are much lower than the septet of ISTC of Cr and the nonet of that of Mn. When going from 3d to 4d, the position providing the maximum spin multiplicity shifts to group V from group VII. These differences arise from the size of the 4d orbital. Because of the larger size of the 4d orbital, the energy splitting between two d(δ) orbitals of M(AIP) and that between the d(δ) and d(π) orbitals are larger in the 4d complex than in the 3d complex. Thus, when occupation on the d(δ) orbital starts, the low spin state becomes ground state, which occurs at group VI. Hence, the ISTC of Nb (group V) exhibits the maximum spin multiplicity. 相似文献
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8.
Leslie S Forster 《Coordination chemistry reviews》2002,227(1):59-92
Photophysical kinetic results have played an important role in assessing excited state relaxation pathways in transition metal complexes. The applicability of a kinetic analysis is critically dependent on the quality of the individual decay rates, the temperature range examined, and the model used to extract the activation parameters. The extensive literature describing the temperature dependence of excited state depopulation in d3 and d6 complexes permits an evaluation of both the power and limitations of kinetic arguments in assessing the mechanism of excited state relaxation. 相似文献
9.
Kaja Schubert Meiyuan Guo Kaan Atak Simon Drner Christine Bülow Bernd von Issendorff Stephan Klumpp J. Tobias Lau Piter S. Miedema Thomas Schlathlter Simone Techert Martin Timm Xin Wang Vicente Zamudio-Bayer Lucas Schwob Sadia Bari 《Chemical science》2021,12(11):3966
The local electronic structure of the metal-active site and the deexcitation pathways of metalloporphyrins are crucial for numerous applications but difficult to access by commonly employed techniques. Here, we applied near-edge X-ray absorption mass spectrometry and quantum-mechanical restricted active space calculations to investigate the electronic structure of the metal-active site of the isolated cobalt(iii) protoporphyrin IX cation (CoPPIX+) and its deexcitation pathways upon resonant absorption at the cobalt L-edge. The experiments were carried out in the gas phase, thus allowing for control over the chemical state and molecular environment of the metalloporphyrin. The obtained mass spectra reveal that resonant excitations of CoPPIX+ at the cobalt L3-edge lead predominantly to the formation of the intact radical dication and doubly charged fragments through losses of charged and neutral side chains from the macrocycle. The comparison between experiment and theory shows that CoPPIX+ is in a 3A2g triplet ground state and that competing excitations to metal-centred non-bonding and antibonding σ* molecular orbitals lead to distinct deexcitation pathways.Near-edge X-ray absorption mass spectrometry (NEXAMS) and restricted active space (RAS) quantum mechanical calculations at the metal L-edge reveal the electronic structure and orbital-specific deexcitation pathways of gas-phase metalloporphyrins. 相似文献
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11.
Lewis M. Broomfield Joseph A. Wright William Clegg Manfred Bochmann 《Journal of organometallic chemistry》2007,692(21):4603-4611
Treatment of MCl3(OC6H3-2-tBu-6-CHNC6F5)(THF) (M = Ti, Zr) with a variety of different potassium iminopyrrolate salts (K+[RNCHC4H3N]−), (R = phenyl, cyclo-hexyl, ethyl) afforded the corresponding titanium and zirconium mixed-ligand complexes MCl2(N-O)(N-N). The molecular structures of TiCl2(OC6H3-2-tBu-6-CHNC6F5)(C2H5NCHC4H3N) (1c), TiCl2(OC6H3-2-tBu-6-CHNC6F5)(C6H11NCHC4H3N) (1b) and ZrCl2(OC6H3-2-tBu-6-CHNC6F5)(C6H11NCHC4H3N) (2b) show distorted octahedral geometries with trans-O−,N−/cis-Cl2 arrangements. On activation with MAO the titanium (iminopyrrolato)(salicylaldiminato) complexes show excellent activities in ethylene polymerisation and are significantly more effective ethylene/propylene copolymerisation catalysts, both in terms of activity and propene incorporation, than either of the parent complexes. The ethylene-propylene copolymers show ca. 80% 1,2 regioselectivity and at high propylene incorporation tend towards an alternating structure. 相似文献
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Mauricio Arias Javier Concepción Irma Crivelli Alvaro Delgadillo Ramiro Díaz Angélica Francois Francisco Gajardo Rosa López Ana María Leiva Bárbara Loeb 《Chemical physics》2006
Different strategies to improve the excited state properties of polypyridinic complexes by varying ligand structure and molecular geometry are described. Bidentate and tetradentate ligands based on fragments as dipyrido[3,2-a:2′,3′-c]phenazine, dppz, and pyrazino[2,3-f][1,10]-phenanthroline, ppl, have been used. Quinonic residues were fused to these basic units to improve acceptor properties. Photophysical studies were performed in order to test theoretical predictions. 相似文献
14.
Molecular orbitals of some of the 3d-transition metal phthalocyanines have been calculated. π-Electron charge densities over the atomic sites and the optical properties of the metal phthalocyanines have been calculated. The effect of the introduction of different metal atoms in the centre of the organic ring on the physical properties of the metal phthalocyanines has been discussed. 相似文献
15.
A brief review of the results of studying some classes of nitrogen-containing chelate boron complexes by ultraviolet photoelectron spectroscopy and density functional theory is reported. The quantum chemical modeling of the substitution effects of a complexing agent, heteroatoms, and functional groups in α, β, and γ positions of the chelate ring allowed us to establish the features of the electronic structure of the studied complexes. It is found that the substitution of heteroatoms in the chelate ring has no substantial influence on the structure of the highest occupied molecular orbital (HOMO). In imidoylamidinate complexes, as opposed to formazanates and β-diketonates, there is no noticeable mixing of π orbitals of the chelate and benzene rings. In condensed nitrogen heterocycles the HOMO is stabilized by 0.2-0.3 eV and π orbitals of the benzene ring are stabilized by 0.8-1.2 eV. The HOMO of substituted aza-boron-dipyridomethene correlates with anthracene and acridine π7 orbitals, which causes the fine structure of the first band. It is shown that in an energy range below 11 eV the calculated results reproduce well the energy gaps between the ionization states of the complexes. 相似文献
16.
INDO SCF calculations have been carried out for the d6 sandwich species FeCp2, CrBz2, CpCrCh, CpMnBz, [CoCp2]+, [MnBz2]+, [CpMnCh]+, and [CpFeBz]+ (Cp = π-C5H5, Bz = π-C6H6, Ch = π-C7H7), and for systems obtained therefrom by the addition of one further electron. For all complexes except CoCp2 the extra electron is predicted to lie in a dominantly ligand level and the species generated to be less stable than the corresponding d6 systems. 相似文献
17.
Bénédicte Garreau-de Bonneval Kathleen I. Moineau-Chane Ching Fabienne Alary Thanh-Tuan Bui Lydie Valade 《Coordination chemistry reviews》2010,254(13-14):1457-1467
Transition metal bis-dithiolene complexes show a large variety of physical properties such as conductivity, magnetism, optics, which render them attractive for new generations of devices. This review scans neutral d8 metal bis-dithiolene complexes as a function of their chemical structure, and the properties that make them top-quality products for applications in the opto-electronic domain. 相似文献
18.
Published data on the electronic structure of boron chelates are summarized for the first time. Ultraviolet photoelectron spectra of vapors, X-ray photoelectron spectra of molecular crystals, and results of modeling within the framework of the density functional theory are analyzed. Data on the effect of substituents on the electronic structure of complexes are systematized. 相似文献
19.
The simple Hückel method was first applied to the electronic structure of the iron-porphyrin complexes by Pullman et al. [12]. In this paper, their work is extended to include (a) the effect of a dipole or a point charge placed at the sixth coordination position, and (b) the effect of a nitrogen atom placed at the fifth coordination position. A set of new parameter values is used, whose estimation is made by directing special attention to their dependence on the charge distribution among the atoms.The resulting charge distribution for ferro-porphyrin seems to be reasonable. The fact that the position of the Soret peak is insensitive to the sixth ligand can be understood from the resulting orbital energy levels.The difficulty of finding a reasonable charge distribution for ferri-porphyrin is discussed.
The research reported in this paper was sponsored in part by the King Gustaf VI Adolf's 70-Years Fund for Swedish Culture, Knut and Alice Wallenberg's Foundation, the Swedish Natural Science Research Council, and in part by the Aeronautical Research Laboratory, OAR, through the European Office, Aerospace Research, United States Air Force.
On leave from Department of Physics, Faculty of Science, University of Tokyo, Tokyo, Japan. 相似文献
Zusammenfassung Die einfache Hückelsche Methode ist auf die Elektronenstruktur der Eisen-Porphyrin-Komplexe zuerst von Pullman et al. [12] angewandt worden. In der folgenden Arbeit wird ihr Verfahren auf (a) die Wirkung eines Dipols oder einer Punktladung an der sechsten Koordinationsstelle und (b) die eines Stickstoffatoms an der fünften erweitert. Ein Satz neuer Parameterwerte wird verwandt, bei deren Bestimmung besonders auf ihre Abhängigkeit von der Ladungsverteilung geachtet wird.Die erhaltene Ladungsverteilung für Ferroporphyrin erscheint vernünftig. Die Unempfindlichkeit der Lage der Soret-Bande gegen den sechsten Liganden ist aus den erhaltenen Energieniveaus zu verstehen.Die Schwierigkeit, eine vernünftige Ladungsverteilung für Ferriporphyrin zu finden, wird diskutiert.
Résumé La simple méthode de Hückel a été appliquée à la structure électronique des complexes fer-porphyrine pour la première fois par Pullman et al. [12]. Dans l'article suivant, leur travail est étendu afin d'inclure (a) l'effet d'un dipôle ou d'une charge ponctuelle sur la sixième position coordinative, et (b) l'effet d'un atome de nitrogène sur la cinquième position. Un jeu de nouvelles valeurs des paramètres est usé qu'on détermine en tenant compte spécialement de leur dépendance de la distribution des charges atomiques.La distribution de charge obtenue pour la ferroporphyrine semble être raisonnable. Le fait que la position de la bande Soret est insensitive contre le sixième ligand, peut être compris à l'aide des énergies des orbitales calculées.La difficulté de trouver une distribution de charge raisonnable pour la ferriporphyrine est discutée.
The research reported in this paper was sponsored in part by the King Gustaf VI Adolf's 70-Years Fund for Swedish Culture, Knut and Alice Wallenberg's Foundation, the Swedish Natural Science Research Council, and in part by the Aeronautical Research Laboratory, OAR, through the European Office, Aerospace Research, United States Air Force.
On leave from Department of Physics, Faculty of Science, University of Tokyo, Tokyo, Japan. 相似文献
20.
Wang H Yang C Zhang Z Wang M Han K 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,64(3):795-800
The ground-state geometries, electronic structures and vibrational frequencies of metal corrolazine complexes, CzM (M=Mn, Co, Ni and Fe) have been studied using B3LYP/6-311 g(d) method. The molecular geometries are sensitive to the species of the metal, and the bond length of the MN is increase with the metal atom radii. The ground-state electronic structures indicate that there are strong interactions between dx2-y2 of the metal fragments and the corrolazine fragments. The calculations also indicate that the CzNi is the stabilest among the four metal corrolazine complexes. Vibrational frequencies of these metal corrolazine complexes were also calculated and were assigned to the local coordinates of the corrolazine ring, which reveals the some common feature of the molecular vibrations of the metal corrolazine complexes as four-coordination metallocorrolazines. 相似文献