共查询到20条相似文献,搜索用时 15 毫秒
1.
D. Snaathorst C.P. Keijzers A.A.K. Klaassen E. De Boer V.P. Chacko R. Gomperts 《Molecular physics》2013,111(3):585-596
The proton hyperfine coupling tensors of the methylene protons in methyl-deuterated copper(II) bis(N,N-diethyldithiocarbamate) in a diamagnetic host crystal of the corresponding nickel complex have been measured by ENDOR spectroscopy. Two intermolecular and all four intramolecular proton coupling tensors could be determined. With the aid of spin densities, obtained from extended Hückel molecular orbital calculations, the anisotropic part of the tensors can be reproduced quantitatively, taking into account all two- and three-centre contributions. Comparison of the transition frequencies which are computed from the theoretical tensors with the experimental transitions enables the tracing of another five tensors which cannot be completely determined experimentally. 相似文献
2.
The interaction of the title complex, [Cu(EtOH-dtc)2], with I2, Br2 and different metal salts known as electron acceptors is studied in water-ethanol solution. Mixed-ligand complexes Cu(EtOH-dtc)+…X? (X = Cl, Br, I, NO3) are formed with X? in the second coordination sphere of the metal ion. Cu(EtOH-dtc)2 interacts with chloral-hydrate only in the presence of weak Lewis bases and Cu(EtOH-dtc)+…Cl? mixed-ligand complex is formed. The interactions with metal chelates cause the formation of mixed-ligand chelate complexes. Cu(EtOH-dtc)2 interacts with H2O2 and the appearance of mixed-ligand complexes as intermediate products is detected. The final product obtained is CuSO4. In the presence of O2 Cu(EtOH-dtc)2 yielded spectra similar to the above intermediate products. The proposed mechanisms of all studied reactions are discussed on the ground of the recorded spectra. 相似文献
3.
The EPR study on equimolar solutions of Cu(dtc)2 and Cu(dtp)2 in aerated acetone, toluene and chloroalkane (CHCl3 and CCl4) solutions indicates that Cu(dtc)(dtp) is the only complex species present in solution. The analysis of the EPR spectra recorded after photo-irradiation in aerated acetone solutions enables the characterization of the intermediate paramagnetic species and provides a reasonable explanation. 相似文献
4.
The effect of acidification of water-ethanol solutions of cyclometalated Pt(II) and Pd(II) complexes with ethylenediamine and cyanide ligands is studied. It is found that, unlike the ethylenediamine complexes, the cyclometalated complexes with cyanide ligands are unstable and undergo irreversible decyclometalation. 相似文献
5.
M. V. Puzyk V. S. Kotlyar N. V. Antonov Yu. A. Ivanov M. A. Ivanov K. P. Balashev 《Optics and Spectroscopy》2000,89(5):721-723
Spectral and luminescent properties of mixed-ligand palladium(II) complexes—[PdBhq(μ-Cl)]2, [PdBhqEn]ClO4, and [PdBhqBpy]ClO4, where Bhq stands for the 7,8-benzoquinoline ion—were studied. The absorption spectra of these complexes in the 25000–40000-cm? range were found to have a number of spin-allowed transitions of the 1(π-π*) type involving orbitals of the 7,8-benzoquinoline ligand. The luminescent characteristics of these compounds in a glass-forming matrix at 77 K are primarily determined by the participation of the 3(π-π*) states of the 7,8-benzoquinoline ligand. 相似文献
6.
N. S. Eremina S. B. Meshkova K. M. Degtyarenko T. N. Kopylova Z. M. Topilova R. M. Gadirov L. G. Samsonova 《Journal of Applied Spectroscopy》2012,79(2):197-202
Spectral and luminescent properties of mixed-ligand Eu(III) complexes were studied in solutions and in polyvinylcarbazole (PVC) thin films. Trends in their variations were found depending on the complex structure and excitation mode. The electroluminescence was observed in ITO/PEDOT/Eu complex:PVC/CaMg/Al devices. Their current-voltage and voltage-brightness characteristics were investigated. 相似文献
7.
C. G. Palivan H. M. N. Palivan B. A. Goodman C. Cristescu 《Applied magnetic resonance》1998,15(3-4):477-488
Electron paramagnetic resonance (EPR) spectroscopy and molecular dynamics calculations have been used to compare the chemical environments of Cu(II) in three substituted asymmetric-triazine (as-triazine) complexes with a closely related complex that was reported previously to have Superoxide dismutase (SOD) and antiviral activities. The structure most strongly associated with the biological activity appears to be planar with two 6-membered chelate rings having 2N2O coordination around the copper atom. 相似文献
8.
V.A. Starodub S.V. Vitushkina D. Kamenskyi A.G. Anders V.O. Cheranovskii H. Schmidt D. Steinborn I. Potočňák M. Kajňaková A. Radváková A. Feher 《Journal of Physics and Chemistry of Solids》2012,73(2):350-356
Mixed-ligand Cu(II) and Ni(II) complexes, [Cu(dmit)(bpy)]2 (I), [Ni(dmit)(phen)2] (II) and [Ni(dmit)(phen)2]·CH2Cl2 (III) (dmit=1.3-dithiole-2-thione-4.5-dithiolate, phen=1.10-phenantroline, bpy=2.2′-bipyridine) have been prepared by ligand exchange between phen or bpy and (Bu4N)2[M(dmit)2] (M=Ni, Cu) and characterized by elemental analysis, IR spectroscopy, single-crystal X-ray analysis and by investigation of magnetic and resonance properties. In complex I, the monomeric units form dimers in a head-to-tail arrangement by weak coordination bonds between copper and dithiolate sulfur atoms and π–π interactions between dmit and bpy from neighboring monomers. Dimers in I are further extended into chains by weak Cu–S(thione) contacts. In crystal packing of complex II and III, there exists a weak π–π interaction between two parallel phen molecules of the adjacent complexes. As a consequence, the magnetic and resonance characteristics of copper complex may be described in approximation of exchange-coupled pairs of Cu2+ ions with ion spin S=1/2. The nickel complexes are described by isotropic exchange model for single-site spin S=1. 相似文献
9.
Electron paramagnetic resonance (EPR) spectrometry and molecular mechanics force field calculations have been performed on some sterically hindered copper(II) complexes with hydrazonotriazine ligands, in order to gain further insight into the relationship between their bonding, structures and biological activity. As was the case with Cu(II) bis(hydrazono-triazine) complexes studied previously, the most stable configuration for all of the complexes involves coordination of two nitrogen and two oxygen atoms (2N2O) in a distorted tetragonal arrangement. With the present complexes, however, the superoxide radical scavenging activities were very low, a result which may be explained by their inability to form a (nearly) square planar structure, which facilitates the copper redox cycling during superoxide dismutation. 相似文献
10.
The chemistry and photochemistry of methylene bromide (CD2Br2) on the rutile TiO2(110) surface was probed using temperature programmed desorption (TPD). CD2Br2 desorbed in three desorption states at 145, 160 and 250 K tentatively assigned to desorption from the multilayer, from an η1-CD2Br2 species and a bridging η2-CD2Br2 species, respectively. The latter two TPD states presumably involve binding of CD2Br2 molecules to the surface through Br coordination at five-coordinate Ti4+ surface sites. The 160 and 250 K TPD states saturated at coverages of 1.0 and 0.33 ML, respectively, where 1 ML is equivalent to the surface Ti4+ site density (5.2 × 1014 cm? 2). No thermal decomposition of CD2Br2 was observed on either the clean surface or with preadsorbed O2. UV irradiation of CD2Br2 on TiO2(110) resulted in predominately photodesorption, with trace amounts of photodecomposition evidenced in TPD. The rate of CD2Br2 photodesorption from TiO2(110) occurred with a low cross section (~ 2 × 10? 21 cm2) similar to that expected from direct optical excitation of CD2Br2. This observation suggests that charge carriers generated in TiO2(110) were no more effective in activating adsorbed CD2Br2 molecules than would be expected through direct molecular excitation. These findings suggest that photocatalytic destruction of halocarbons such as CD2Br2 on TiO2 may preferentially occur though indirect processes (such as OH radical attack) as opposed to direct electron transfer processes involving charge carriers generated in TiO2 by bandgap excitation. 相似文献
11.
D.C. Frost C.A. McDowell R.L. Tapping 《Journal of Electron Spectroscopy and Related Phenomena》1975,6(5):347-355
Satellite structure in the X-ray photoelectron (Cu 2p) spectra of some squareplanar cupric complexes has been compared to electron paramagnetic resonance and electronic spectra results on the electronic structure of these complexes. It is shown that these satellites can be assigned to various ligand → metal 3d or ligand → ligand* transitions within the monopole selection rules of the sudden approximation. 相似文献
12.
Christiane G?rller-walrand 《Molecular physics》2013,111(11-12):1361-1365
A symmetry concept is proposed that links the presence of vibronic structure in UV-visible spectra in d-systems, with the identification of a single photochemical reaction pathway. It is shown that the vibronic structure on some bands of the Pt(II) D4h complexes is due to the non- degenerate, ungerade b1u (xyz) vibration that points on an intramolecular twisting process for the photochemical cis-trans isomerization. The reaction coordinate is unambiguously defined in a coordinate system where x and y bisect the metal-ligand ML2 angle. 相似文献
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15.
Jagdish Prasad Vijai Krishna Hira Lal Nigam 《Journal of Physics and Chemistry of Solids》1977,38(10):1149-1152
The X-ray K-absorption edge position and the extended fine structure of copper in some copper(II) carboxylate complexes involving metal-metal exchange interaction have been investigated using a 40 cm bentcrystal spectrograph. It has been found that the edge position in these complexes shifts towards the higher energy side as the pKa value of the corresponding acids increases. Sharp and narrow main peaks have been observed in all these complexes except the monomeric complex, copper(II) trichloroacetate. Estimates of metal-ligand average bond distances have also been made. 相似文献
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17.
C. Battistoni M. Bossa C. Furlani G. Mattogno 《Journal of Electron Spectroscopy and Related Phenomena》1973,2(3):355-361
N 1s, S 2p and Ni 2p3/2 binding energies for the Ni(II) dithiocarbazates and N 1s and S 2p binding energies for the methyl esters of dithiocarbazic acids were measured. It was found that the band width of N 1s narrows on going from the esters to the complexes, thus suggesting a closer similarity between the two nitrogen atoms as a consequence of coordination. S 2p binding energies were found to be similar in the above complexes independent of the chromophore present in them. A possible explanation is suggested for this unusual result. 相似文献
18.
The copper K-absorption edge in the complexes Cu(ammonia)2 C2O4, Cu(methylamine)2 C2O4, Cu(ethylamine)2 C2O4 and Cu(aniline)2 C2O4 has been investigated using the Cauchois-type bent crystal X-ray spectrograph. Three peaks, A, B and C, observed in the edges have been explained on the basis of molecular orbital theory. 相似文献
19.
Abhijeet Gaur B. D. Shrivastava K. Srivastava J. Prasad Sandeep K. Singh 《X射线光谱测定》2012,41(6):384-392
X‐ray absorption fine structure spectra have been investigated at the K‐edge of copper in copper(II) salen/salophen complexes: [Cu(salen)] (1), [Cu(salen)CuCl2].H2O (2), [Cu(salophen)] (3) and [Cu(salophen) CuCl2].H2O (4), where salen2? = N,N′‐ethylenebis (salicylidenaminato); salophen2? = o‐phenylenediaminebis(salicylidenaminato). Complexes 1 and 3 are supposed to have one type of copper centers (called (Cu1)) and complexes 2 and 4 two types of copper centers (called (Cu1) and (Cu2)) having different coordination environments and geometries. A theoretical model has been generated using the available crystallographic data of complex 1 and it has been used for analysis of the extended X‐ray absorption fine structure (EXAFS) data of the four complexes to obtain the structural parameters for (Cu1) center. For this center, the obtained Cu–Cu distance (3.2 Å) verifies the binuclear nature of all the complexes. For determining the coordination geometry around (Cu2) center in 2 and 4, a theoretical model has been generated using the crystal structure of a Cu(II) complex, [Cu(C16H12N2O2Cl2)]. This theoretical model has been fitted to the EXAFS data of 2 and 4 to obtain the structural parameters for (Cu2) center. The present analysis shows that (Cu1) center has square pyramidal geometry involving 2N and 3O donor atoms, whereas (Cu2) center has distorted tetrahedral geometry with 2O and 2Cl donor atoms. The values of the chemical shifts and presence of typical Cu(II) X‐ray absorption near‐edge spectroscopy features suggest that copper is in the +2 oxidation state in all these complexes. The intensity of ls → 3d pre‐edge feature has been used to investigate the geometry and binuclear nature of the complexes. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
20.
R. V. Gulyaev N. A. Kryuchkova L. N. Mazalov A. I. Boronin T. V. Basova V. A. Plyashkevich 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2011,5(1):48-56
The charged states of atoms in unsubstituted copper(II) phthalocyanine (CuPcH16) and hexade-cafluorinated copper(II) phthalocyanine (CuPcF16) complexes and in thin films of them deposited on silicon substrates by vacuum thermal evaporation are investigated by X-ray
photoelectron spectroscopy (XPS). The C(1s), N(1s), Cu(2p) core level energies and the charged states of atoms in the studied complexes are calculated using the DFT method. The performed
experimental study and theoretical calculations show that the introduction of electron acceptor substituents into benzene
rings mostly affects the atoms of benzene rings and insignificantly affects the charge state of nitrogen atoms in the pyrrole
ring. 相似文献