Yu. V. Chizhov

Photoelectron spectroscopy of molecular systems and quantum-chemical calculations in terms of the density functional theory: Iron π complexes L-Fe(CO)3

The HeI and NeI photoelectron spectra of irontricarboniyl complexes with cyclic diene ligands—αmethylstyrene, orthoquinodimethane, and cyclooctatetraene—were obtained. The results of quantum-chemical calculations of the molecules of these compounds in the approximation of the density functional theory (B3LYP/6-31G*) are presented. It is shown that this approximation describes well the excited ionic states of the π complexes under study. The relative ionization cross sections σπ and σ3d, which characterize the probability of removal of electrons from the molecular π-ligand and 3d-metal orbitals, are estimated. The mechanism of the selective coordination of the Fe(CO)3 groups to corresponding organic ligands is discussed. The energies of the L-Fe(CO)3 chemical bond are calculated.

Study of redox reactions of bis(arene) chromium complexes by the rotating disk electrode technique. IV: Electrochemical oxidation and ionization potentials of bis(arene) chromium complexes

Abstract The reversible electrochemical oxidation of a series of bis(arene)chromium com-plexes has been studied by use of the rotating disk electrode technique The half-wave potentials E 1/2 show an excellent correlation with the meta -substituent constants. The E 1/2 values were found to correlate well with the vertical ionization potentials ( IP ) of the same complexes in the gas phase determined from their He(I) photoelectronic spectra.

Electronic structure of bis-arene-chromium complexes

Abstract Dibenzenechromium derivatives of the type (C 6 H 5 R 1 )Cr(C 6 R 5 R 2 ) have been studied by He-I photoelectron spectroscopy. Substituent parameters have been found which allow the first and second ionization potentials of the bis-arene-chromium complexes to be determined using a very precise additive scheme. It has been shown that the change in the energy of the highest occupied MOs of the molecules is determined by the electrostatic field of ligands. The molecular electrostatic potentials of a number of species (C 6 H 5 R 1 )(C 6 H 5 R 2 ) have been calculated and the equation relating IP to ϕ( R ) has been found. A scheme for constructing the energy level diagram for dibenzenechromium and its derivatives is suggested.

Density-functional theory calculation on the nitrogen oxide reduction reaction with carbon monoxide on a titanium dioxide nanocluster

The density functional theory was used for simulation of the NO reduction reaction with carbon monoxide on a reduced Ti8O15 nanocluster. The reaction proceeds on oxygen vacancies formed via the removal of terminal or bridging O atoms. In the case of adsorption of two NO molecules of such sites, a stable adsorption complex with the bidentate ligand ‥ONNO is produced. When a CO molecule approaches one of the O atoms of this cycle, the following exothermic reaction yielding N2 and CO2 adsorbed on the Ti8O16 cluster takes place: 2NO+ CO + Ti8O15 → N2+ Ti8O16 · CO2. The proposed model of the reaction agrees well with experimental data.

Photoelectron spectroscopy of irontricarbonyl complexes of vinylnaphthalenes: Quantum-chemical calculations by the density functional method

The HeI photoelectron spectra of the complexes η4-1-vinylnaphthalene-Fe(CO)3 and η 4-2-vinylnaphthalene-Fe(CO)3 and the free organic ligands 1-vinylnaphthalene and 2-vinylnaphthalene are measured. The spectra are interpreted on the basis of quantum-chemical calculations by the density functional method in the SVWN/6-31G(d) local density approximation and with the B3LYP/6-31G(d) hybrid exchange-correlation functional. The Kohn-Sham orbital energies with calibration corrections are shown to reproduce well the vertical ionization potentials of both the irontricarbonyl π complexes under study and their ligands. The relative ionization cross sections σi of the valence orbitals of the complexes are calculated in terms of the Gelius model. These quantities prove to agree perfectly with the relative ionization cross sections σiexp determined experimentally from direct estimation of the band areas of the photoelectron spectra.

Photoelectron spectra and the structure of organomercury compounds

The He(I) photoelectron spectra of 30 organomercury compounds of different structural types and of some model organic compounds were investigated. Also the values of vertical ionization potentials (IP) of highest occupied molecular orbitals (HOMO) were determined. Several relationships were studied in IP in this series of compounds. A method was developed to separate the contributions of electron effects to changes in the IP of HOMO. The induction effects of HgCl and CH2HgCl groups as well as the effect of σ(CHg), π-conjugation in the alkene and benzyl derivatives of mercury were estimated. The influence of structural and other factors on the magnitude of this effect was studied.

Theoretical estimation of the electron affinity for quinone derivatives by means of density functional theory

A number of compounds related to quinone derivatives is investigated by means of density functional theory in the B3LYP/6-31G(d) mode. Vertical electron affinity Eva and/or electron affinity Ea for the investigated compounds are known from experiments. The correlation between the calculated energies of π* molecular orbitals with the Eva values measured via electron transmission spectroscopy is determined with a coefficient of 0.96. It is established that theoretical values of the adiabatic electron affinity, calculated as the difference between the total energies of a neutral molecule and a radical anion, correlate with Ea values determined from electron transfer experiments with a correlation coefficient of 0.996.

Investigation of the mechanism of fragment coordination of aromatic molecules with transition metals by photoelectron spectroscopy-tricarbonyliron complexes

ConclusionsThe changes in the chemical shifts of organic molecules during complex formation are well known in organometallic chemistry [24]. Thus, coordinated dienes lose the olefinic characteristics; they are not hydrogenated, do not enter into the Diels-Alder reaction, and react with electrophilic reagents. At the present time the search for a link between the structure of organometallic complexes in terms of rigorous quantum-chemical calculations is beginning. The construction of experimentally substantiated models which make it possible to explain qualitatively the marked changes in the characteristics of organic compounds in the presence of the atoms of transition metals is therefore essential for a deeper understanding of the orbital mechanisms lying at the basis of catalysis.The PE spectra were measured on an ÉS 3201 electron spectrometer with an inlet system heated to 200°C. The resolution, determined from the width of the2P3/2Xe band at the half-height, amounted to 40 meV. Compounds (II) and (III) were obtained by the previously described methods [25, 26], and the analytically pure substances were used for the investigation.

Comparative analysis of metal-binding centers in homologous domains of human coagulation factor VIII and ceruloplasmin

Comparative Analysis of Metal-Binding Centers in Homologous Domains of Human Coagulation Factor VIII and Ceruloplasmin I. V. Krauklisa, Yu. V. Chizhova, V. G. Maslovb, V. E. Stefanova, and K. A. Moshkova* a St. Petersburg State University, St. Petersburg, Russia b St. Petersburg National Research University of Information Technologies, Mechanics and Optics, St. Petersburg, Russia * e-mail: moshkovspbu@gmail.com

Spectroscopy and quantum-chemical calculations of nitro-bis-bipyridyl complexes of ruthenium(II) with 4-substituted pyridine ligands

The luminescence, absorption, and luminescence excitation spectra of complexes cis-[Ru(bpy)2(L)(NO2)]+ [bpy = 2,2′-bipyridyl, L = pyridine, 4-aminopyridine, 4-dimethylaminopyridine, 4-picoline, isonicotinamide, or 4,4′-bipyridyl] in alcoholic (4 : 1 EtOH–MeOH) solutions are studied at 77 K. A linear correlation is established between the energy of the lowest electronically excited metal-toligand charge transfer state dπ(Ru) → π*(bpy) of the complexes and the pKa parameter of the free 4-substituted pyridines used as ligands L. The B3LYP/[6-31G(d)+LanL2DZ(Ru)] hybrid density functional method is used to optimize the geometry of complexes and calculate their electronic structure and the charge distribution on the atoms of the nearest environment of ruthenium(II) ions. It is shown that there exists a mutually unambiguous correspondence between the charge on the nitrogen atom of ligands L coordinated in the complex and the pKa parameter of ligands. The calculated energies of the electronically excited metal-to-ligand charge transfer states of complexes linearly (correlation coefficient 0.99) depend on the charge on the nitrogen atom of ligands L, which completely agrees with the experimental data.