A. A. Tsaturyan

Influence of the bridging coordination of DMSO on the exchange interaction character in the binuclear copper(II) complex with the nonsymmetrical exchange fragment

The binuclear copper(II) complex [Cu2L(CH3COO)] (I), where L3− is the azomethine trianion based on 3-methyl-4-formyl-1-phenylpyrazol-5-one and 1,3-diaminopropan-2-ol, and its DMSO adduct (II) in which the DMSO molecule acts as an additional bridging ligand are synthesized. The structure of complex II is determined by X-ray diffraction analysis, and the structure parameters of the coordination unit of complex I are determined by EXAFS spectroscopy. The μ2-coordination of the DMSO molecule in compound II results in a change in the sign of the exchange interaction parameter. In complex I, the antiferromagnetic exchange interaction (2J = −169 cm−1) occurs between the copper(II) ions. The exchange interaction of the ferromagnetic type (2J = 174 cm−1) is observed in complex II. The quantum-chemical calculations of the magnetic exchange parameters by the density functional theory method show that the role of the DMSO molecule as a switch of the exchange interaction character is exclusively the stabilization of the “broken” conformation of the metallocycles.

Binuclear Complexes of Copper(II) with 1'-Phthalazinylhydrazones of Substituted Salicylic Aldehydes: Physico-Chemical Study and Quantum-Chemical Simulation

Binuclear complexes of copper(II) with 1′-phthalazinylhydrazones of substituted salicylic aldehydes have been prepared and studied. Antiferromagnetic exchange interaction between copper(II) ions has been revealed in all the complexes. Taking advantage of quantum-chemical simulation, we have investigated the influence of the complexes structural isomerism on the character of the exchange interaction between the paramagnetic centers. X-ray absorbance spectroscopy afforded the structural parameters of coordination spheres of copper(II) ions; it has been demonstrated that dimerization occurred via the nitrogen atoms of phthalazine fragments.

Tetranuclear copper(II) complex with the heterocyclic azomethine ligand: Crystal structure and magnetic properties

A tetranuclear copper(II) complex based on azomethine, which is the condensation product of 1-phenyl-3-methyl-4-formylpyrazol-5-one with 1,3-diaminopropan-2-ol, is synthesized. The complex includes two different tetranuclear clusters: symmetrical and unsymmetrical. They have a pseudo-cubane structure and are in a ratio of 1 : 2. The quantum-chemical calculation shows that the “unsymmetrical” conformer does not correspond to the local minimum on the molecular potential energy surface. Its existence is thus determined by the crystalline packing effects. According to the results of measurements of the temperature dependence of the magnetic susceptibility, the ground spin state is a singlet caused by the overall antiferromagnetic interaction between the copper ions. Accepting the molar magnetic susceptibility of the complex to be equal to the sum of susceptibilities of the “symmetrical” and “unsymmetrical” clusters and assuming that the spin-Hamiltonian for both clusters includes three exchange parameters, the temperature dependence of the magnetic susceptibility of the complex is satisfactorily described with the following parameters of the model: J1A = −178, J2A = 80, J3A = 18, J1B = −26, J2B = −74, J3B = 46 cm−1, gA = gB = 2.05.

2-(N-tosylamino)benzaldehyde thiobenzoylhydrazone and its complexes with copper(II) and zinc(II): Synthesis and structures

Abstract2-(N-Tosylamino)benzaldehyde thiobenzoylhydrazone and its copper(II) and zinc(II) complexes with dimethylformamide (DMF) and methanol, [CuL(DMF)] and [ZnL(CH3OH)], respectively, were synthesized. The structures of the copper(II) complex and the cyclic product of hydrazone oxidation (1,3,4-thiadiazole derivative) were determined by X-ray diffraction analysis.

Crystal structure of bis-Isonicotinoyl hydrazone of 2,5-diformylpyrrole

Abstractbis-Isonicotinoyl hydrazone of 2,5-diformylpyrrole existing in the crystal in the form of a tetrahydrate of the hydrazone tautomeric form is synthesized and its structure is described. In the crystal, an infinite three-dimensional network of hydrogen bonds is formed by hydrazone molecules. The neighboring hydrazone molecules are bonded by intermolecular π stacking interactions. A quantum chemical calculation of the geometry and total energy of possible tautomers in vacuum and an aqueous solution is performed.

Transition Metal Complexes with 2,6-Di-tert-butyl-p-quinone 1 '-Phthalazinylhydrazone

Abstract2,6-Di-tert-butyl-p-quinone 1′-phthalazinylhydrazone (HL) was synthesized. Quantum-chemical calculations of the energy of possible tautomeric forms of the hydrazone were performed. The complexes of Zn(II), Hg(II), Ni(II), and Cu(II) of ML2 composition were obtained and studied. The structure of the NiL2 complex was established by XRD. It was shown by DFT-D3 calculations that the cis-structure of the complex is stabilized due to the interligand dispersion interaction.

Crystal structure and magnetic properties of the binuclear copper(II) complex with 2,6-diformyl-4-tert-butylphenol bis(imidazolinylhydrazone)

The binuclear copper(II) complex with 2,6-diformyl-4-tert-butylphenol bis(imidazolinylhydrazone) (H3L), [Cu2(H2L)Br2]ClO4 (I), was synthesized. The structure of complex I was determined by X-ray diffraction analysis. The antiferromagnetic exchange interaction (2J = −108 cm−1) translated through the phenoxide oxygen atom is observed between the copper(II) ions. The exchange parameter was calculated by the quantum-chemical “broken symmetry” method.

Iron(II) and ruthenium(II) complexes with polypyridine derivatives as sensitizers for DSSC: the structure and spectral properties, as studied by quantum chemistry methods

Density functional calculations of the geometries, electronic structures, and spectral properties of a series of iron(II) and ruthenium(II) complexes with 4,4´,4´,4´´-substituted 2,2´:6´2´´:6´´,2´´´-quaterpyridines were carried out. A high-spin state is characteristic of the iron(II) complexes with Cl–, NO–, CNS–, and I– as axial ligands while a low-spin state is characteristic of the iron(II) complex with a CN– axial ligand. Calculations of the complexes with the nitroxide ligand predict intense absorption in a wide wavelength range up to the IR region.

Influence of the number of anchor groups on the photophysical properties of coordination compounds as components of dye-sensitized solar cells

The geometry, electronic structure and properties, and composition of frontier molecular orbitals of the FeII complex with 4,4´,4´´,4´´´-substituted 2,2´:6´,2´´:6´´,2´´´-quaterpyridine were examined using quantum chemical simulation. This compound was proposed for use as a photoactive component in dye-sensitized solar cells. The regularities were established of the influence of the number of carboxyl groups in the molecular structure on the composition and energy of the frontier orbitals determining the electronic absorption spectra of the studied compounds. The presence of two COOH groups in the structure of the studied complex is the most optimal for use as a sensitizer.

Structure and magnetic properties of binuclear copper(II) complexes with 2,6-diformyl-4-tert-butylphenol bis(imidazolinyl)hydrazone

Binuclear copper(II) complexes with bis(imidazolinyl)hydrazone of 2,6-diformyl-4-tert-butylphenol have been prepared and studied. In all complexes the antiferromagnetic exchange interaction between the copper(II) ions is observed.