THE 15-Th V.A. FOCK MEETING on QUANTUM and COMPUTATIONAL CHEMISTRY

Russian Foundation for Basic Research Division for Computational Chemistry at the European Association of Chemical and Molecular Sciences Division for Computational Chemistry at the D.I. Mendeleev Chemical Society of Russia M.V. Lomonosov Moscow State University Far Eastern Federal Universtity Institute of Chemistry FEB RAS

THE 15-th V.A. FOCK MEETING ON QUANTUM AND COMPUTATIONAL CHEMISTRY

Book of Abstracts

A.L. Tchougréeff – Editor

Scientific Electronic Publishing

Vladivostok Far Eastern Federal Universtity 2015

The 15-th V.A. Fock Meeting on quantum and computational chemistry F17 [Electronic resource] : Book of Abstracts / Russian Foundation for Basic Research, Division for Computational Chemistry at the European Association of Chemical and Molecular Sciences, Division for Computational Chemistry at the D.I. Mendeleev Chemical Society of Russia, M.V. Lomonosov Moscow State University, Far Eastern Federal Universtity, Institute of Chemistry FEB RAS ; ed. A.L. Tchougréeff. – Electronic Data. – Vladivostok : Far Eastern Federal Universtity, 2015. – 1 СD ROM. – System Requirements: Processor with a Frequency of 1.3 GHz (Intel, AMD); RAM 256 MB free space on hard drive 335 MB; Windows (XP; Vista; 7 etc.); Acrobat Reader, Foxit Reader or Any Other Analog Thereof. – Screen Title. ISBN 978-5-7444-3697-1.

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© FEFU, 2015 International Organizing Committee for the Meeting: V.V. Lunin (MSU); A.L. Buchachenko (MSU); V.I. Sergienko (FEB RAS); V.I. Minkin (IPOC RSU); V.V. Tartakovsky (IOC RAS); A.A. Berlin (ICP RAS); I.V. Abarenkov (SPbSU); R. Dronskowski (RWTH); F. Illas (IQTCUB); P.G. Szalay (Eötvös University); A.L. Tchougreeff (RWTH - Aachen Universtity/MSU/MCCME); A.Y. Ustinov (FEFU/IC FEB RAS).

Advisory Board for the Meeting: A.L. Buchachenko (ICP RAS - chairman); I.B. Bersuker (Moldavian Academy of Science/Texas A&M University); R. Hoffmann (Cornell University); R.A. Evarestov (SPbSU - vice chairman) G.M. Zhidomirov (MSU - vice chairman); P. Alemany (Universidad Barcelona); F. Illas (IQTCUB); R. McWeeny (University of Pisa); R.R. Nazmutdinov (KSTU); R.M. Minyaev (IPOC SFU); G. Naray- Szabo (Eötvös University); P.N. Dyachkov (IGIC RAS); A. Savin (P&M Curie Université Sorbonne); P. Fulde (MPIPKS Dresden); W. Thiel (MPI Muelheim); J.-P. Piquemal (P&M Curie Université Sorbonne); V.I. Pupyshev (MSU); A.L. Tchougreeff (RWTH - Aachen Universtity/MSU/MCCME); A.Y. Ustinov (FEFU/IC FEB RAS); A.Y. Zakharov (NovSU). Conference photo, thanks to Dr. O. Gromov (MSU, Russia) taken at the excursion “Vladivostok at night” on June, 22, 2015. The number on the monument (9288) states the distance from Moscow along the Transsiberian railway and we end of which the photo had been taken. Contents INVITED AND PLENARY LECTURES ...... 8 W.H.E. Schwarz, J. Li Chemical Aspects of the Actinoid Series ...... 8 H. Bolvin Magnetic properties of actinide complexes : a theoretical approach ...... 9 A.M. Pradipto, R. Maurice, R. Broer Local Approach to Isotropic and Anisotropic Magnetic Interactions in Copper Oxides ...... 10 P. Alemany Analyzing the Interplay Between Local and Global Symmetries in molecular chemistry ...... 11 E. Matito, E. Ramos-Cordoba, M. Rodriguez-Mayorga, P. Salvador New Measures of Dynamic Electron Correlation in Terms of Natural Orbitals and Their Occupancies ...... 12 E. Bichoutskaia Recent Progress and Remaining Challenges in Electrostatics ...... 13 R. Dronskowski A chemical (bonding) perspective on phase-change and related materials ...... 14 A.V. Titov, Yu.V. Lomachuk, L.V. Skripnikov, A.V. Zaitsevskii, N.S. Mosyagin, A.N. Petrov ..... 15 Concepts of effective states of atoms in chemical substance and fundamentals of core pseudopotential theories ...... 15 N.P. Gritsan, E.A. Suturina, A.Dmitriev Magnetic properties of 4f- and 5d-metal complexes with redox-active ligands: non-perturbative account of spin-orbit coupling ...... 16 T. Onishi Chemical Bonding Analysis and Materials Design for Energy-Related Materials ...... 17 E.A. Koblova, O.L. Shcheka, A.Yu. Ustinov Plasma electrolytic oxidized coatings on aluminum and titanium: composition, structure, properties ...... 18 X. Assfeld Tackling Electronic Excited States in Complex Surroundings ...... 19 ORAL CONTRIBUTIONS ...... 20 A.D. Kudashov, L.V. Skripnikov, A.N. Petrov, N.S. Mosyagin, A.V. Titov Effects of parity and time-reversal symmetry violation in diatomics ...... 20 L.G. Bulusheva, O.V. Sedelnikova, V.O. Koroteev, A.L. Chuvilin, A.V. Okotrub Electron transitions in rippled and twisted graphenes ...... 21 A.V. Okotrub, L.G. Bulusheva, I.P. Asanov, T.L. Makarov Electronic and magnetic properties of the fluorinated graphenes ...... 22 N.M. Vitkovskaya, V.B. Kobychev, E.Yu. Larionova, V.B. Orel, A.D. Skitnevskaya, B.A. Trofimov Ambivalent reactivity of acetylenes in the presence of superbase: a quantum-chemical insight ...... 23 A.Y. Timoshkin, A.S. Lisovenko Computational study of complexes of Lewis acids with inorganic benzene analogs: Stability and reactivity ...... 24 A . V. Pomogaeva, K. Morokuma, A . Y. Timoshkin Hydrogen-Release Mechanisms in Tetramer of Lithium Amidoborane ...... 25 L.V. Skripnikov, A.N. Petrov, A.V. Titov What relativistic quantum chemistry can give to the search for a new physics? ...... 26 A. Assilbekova Effect of an external electrostatic field on the electronic transitions in small CdS clusters ...... 27 A.N. Petrov, L.V. Skripnikov, A.V. Titov Hyperfine and Zeeman Interaction in diatomics for electron electric dipole moment search...... 28 V.V. Stegailov, P.A. Zhilyaev Pressure in electronically excited warm dense metals: Density functional theory analysis ...... 29 T.B. Emelina, A.G. Mirochnik Optical Chemosensor Properties of Europium(III) chelates. Quantum chemical calculations ...... 30 A.A. Rybakov, A.V. La ri n Similarities between amorphous and microcrystalline forms of hydrogenated silicon from periodic DFT modeling of IR spectra ...... 31 I.A. Kurbatov, A.Ya. Freidzon, V. I. Kharchenko, A.I. Cherednichenko, I. V. Taidakov Calculation of energy transfer parameters in the photoactive complex of europium by multireference quantum-chemical methods...... 32 E.G.R. de Arruda, A. Domingo, Q. Phung, A.L.B. Formiga, K. Pierloot Tuning the spin crossover phenomenon through fine control of nitrogen positions on imidazol-diazine Fe(II) complexes .... 33 V.G. Kiselev, D.E. Mashkantsev, N.P. Gritsan Thermal Decomposition of High-Energy Compounds: New Insights from High-level ab initio Calculations ...... 34 F. Ruette, A. Peraza, M. Sánchez, M. López A general interface for computational chemistry and applications ...... 35 T. Sako Structure of genuine and conjugate Fermi holes in two-electron systems and its applications for correlation problems ...... 36 G. Saleh, A.R. Oganov High pressure alkali subhalides: Insights into their chemical bonding and rationalization of their stability ...... 37 E.A. Koblova, S.E. Malykhin, A.Yu. Ustinov DFT modeling of the catalytic CO oxidation on the Ni-Al metal oxide surface formed via plasma electrolytic oxidation ...... 38 A. Pershin, P.G. Szalay Development of highly accurate approximate scheme for computing the charge transfer integral ...... 39 POSTERS...... 40 F. Cimpoesu, H. Ramanantoanina, B. Herdem, W. Urland, C. Daul Non-empirical prediction of the photophysical and magnetic properties of systems with open d- and f-shells based on combined Ligand Field and Density Functional Theory (LFDFT) ...... 40 A.L. Tchougreeff Effective Hamiltonian Crystal Field: Present Status and Applications ...... 41 S. Mersmann, H. Mouhib, M. Baldofski, G. Raabe Quantum-Chemical ab initio Calculations on Ala- (C5H5Al) and Gallabenzene (C5H5Ga)...... 42 R.W.A. Havenith, R. Broer, W.C. Nieuwpoort Nonorthogonal Approach for Intermolecular Transitions ...... 43 O.A. Gapurenko,V.Ya. Lee, R.M. Minyaev, V.I. Minkin Stabilization of plane basal rings in silicon pyramidal systems ...... 44 L. V. Yakushevich, L.A. Krasnobaeva Forced oscillations of the DNA nitrous bases ...... 45 A.A. Dotsenko, V.I. Vovna, V.V. Korochentsev, A.G. Mirochnik Electronic structure of tellurium(IV) halide complexes with guanidine and cesium ...... 46 N.M. Vitkovskaya, E.Yu. Larionova, V.B. Kobychev, V.B. Orel, A.D. Skitnevskaya, B.A. Trofimov Stereoselectivity of the methanol, methanthiol and ketones vinylation with substituted acetylenes in the KOH/DMSO superbasic medium: quantum chemical study ...... 47 A.S. Lisovenko, A.Y. Timoshkin Influence of Metal Nature on the Formation of Amidoboranes of alkali and alkaline-earth metals ...... 48 A.B. Usseinov, E.A. Kotomin, Yu.F. Zhukovskii, A.T. Akilbekov, F.U. Abuova First principles calculations of the electronic properties of oxygen vacancy of ZnO ...... 49 V.V. Korochentsev, V.I. Vovna, I.S. Osmushko, A.G. Mirochnik Electronic structure lumenescence comlexes of rare-earth elements (Sc, Y, La ) from the results of studies density functional theory 50 Yu. V. Fedoseeva, L.G. Bulusheva, A.V. Okotrub, M. Kosinova, E. Flahaut, J. Zhou, H. Song X- ray spectroscopy and quantum-chemical calculations to understand the chemical bonding in modified carbon nanomaterials ...... 51 A.V. Pomogaeva, A.Y. Timoshkin The Effect of Terminal Groups on Electronic Properties of [RGaNH]3n (R=H, CH3) nanorods ...... 52 A.A. Milov, R.M. Minyaev, V.I. Minkin The structure of atmospheric gases (N2, CO, Ar) polymolecular clusters ...... 53 E.I. Yuryeva The relaxational model of superconducting temperature forming and the example of its possible application...... 54 O.B. Gadzhiev, S.K. Ignatov, A.E. Masunov, A.G. Razuvaev Chemical modification of Pt particles surface in nanocatalysis: a DFT study on the Pt40 and Pt41 clusters ...... 55 S.N. Belyaev, S.V. Panteleev, S.K. Ignatov Structural, electronic, thermodynamic and spectral properties of magnesium clusters Mgn (n=2-31). A DFT study ...... 56 M.A. Zasovskaya, S.K. Ignatov Еlementary reactions of the cluster mechanism of SOCl2 hydrolysis in the gas phase ...... 57 V.B. Kobychev, N.M. Vitkovskaya, V.B. Orel, B.A. Trofimov Ketones reactions with phenylacetylene in the KOH/DMSO superbasic system ...... 58 V.I. Kharchenko, A.I. Cherednichenko, L.N. Alexeiko A Nexus between Electronic Structure and Spectral Properties of the Biologically Active Compound – Echinochrome A: a Quantum Chemical Study ...... 59 C. Tantardini, S.G. Arkhipov, E.V. Boldyreva The effects of noncovalents interactions in the co-crystal of Piroxicam and Meloxicam with carboxylic acids like co-formers ...... 60 D.Yu. Soshnikov, A.B. Trofimov, D.M.P. Holland Multi-state vibronic interactions in cis-1,2- dichloroethene radical cation ...... 61 A.G. Starikov, A.A. Starikova, V. I. Minkin Mechanism of spin-state changing of Ni(II) diketonates under self-association. Quantum chemical modeling ...... 62 V.G. Savchenko, Yu.V. Babin A Theoretical Study Of Ethyne Hydroformylation On Platinum Complexes With Hydrophosphoryl Ligands ...... 63 T.N. Gribanova, R.M. Minyaev, V.I. Minkin Electron-count rules for extended-chain bipyramidal and sandwich complexes of s- and d-metals...... 64 A.A. Rybakov, A.V. Larin, G.M. Zhidomirov Pros and cons of accelerated modeling of Si(110) passivation by atomic layer deposition of Al2O3 ...... 65 D.V. Glukhov, P. Quaino, S.A. Shermukhamedov, R.R. Nazmutdinov Structure of NiCu Nanoparticles as derived from Monte Carlo and Molecular Dynamics simulations ...... 66 I.D. Sorokin, O.I. Gromov, V. I. Pergushov, M.Ya. Melnikov Photochemistry of 1,4-dithiane and aziridine cation radicals ...... 67 C.D . V. Silva Modeling complex mixtures of asphaltenes and heavy oils at mesoscopic level by numerical simulation of Dissipative Particle Dynamics (DPD) ...... 68 M. Fernandez, R. Marin, F. Ruette Interactions between water, free radicals, and magnesium species on cellular membrane to study preeclampsia syndrome ...... 69 + R. Hernandez A generalization of Hellmann-Feynman theorem. Applications to H2, H2 + and H3 ...... 70 A.I. Okhapkin, S.K. Ignatov, G.I. Nikonov Three-step adition of phenylsilane to imido t complex ( BuN=)2Mo(PMe3)2 : hydrosilylation mechanism and stability of intermediates in solvents ...... 71 S.K. Ignatov, O.B. Gadzhiev, A.I. Okhapkin, A.G. Razuvaev Selective hydrogenation of unsaturated aldehydes on the chemically modified sub-nanoparticle Pt24. A quantum chemical study ...... 72 V.V. Koval’, I.V. Getmanskii, R.M. Minyaev Tetrahedral boron and aluminium crystal structures ...... 73 Invited and Plenary Lectures

1907

Chemical Aspects of the Actinoid Series

W. H. Eugen Schwarz and Jun Li

Theoretical Chemistry Center, Tsinghua University, 100084 Beijing, China & Physical Theoretical Chemistry Group, Universität Siegen, 57068 Siegen, Germany

Abstract: The 5f-block elements, in particular the earlier ones, possess a particularly rich valence shell comprising s, p, d and f atomic orbitals of competitive relevance. Direct-Hamiltonian & self-consistent orbital effects of scalar relativity & spin-orbit coupling as well as the common core-shielding & centrifugal effects all play a role, in addition to Coulomb correlation & angular momenta coupling. The demands of reliable computational approaches are challenging. Density functionals sometimes work, sometimes behave catastrophically like in the first-row transition metal series. Compounds of the first actinoid (An) octet of elements (Ac, Th, Pa, U, Np, Pu, Am, Cm) exhibit many astonishing bonding properties. Five examples are here discussed. (1) Carbon in C(σππ&sigma)U(σπ)X may be more convincingly called quadruply bonded than in famous C2, because the rich valence shell of U allows C-2s,2p to form two σ-bonds in the same direction. (2) Instead of a YC=AnX σπ-double-bond, the spin-uncoupled diradical YC•-•AnX may be more stable, owing to large two-electron Coulomb and one-electron spin-orbit interactions. (3) Actinoid oxide molecules show exciting patterns of electronic-geometric structures, owing to 2- 1- 2- 1- 0 various bonding patterns to oxygen in the form of O , O , O2 , O2 , O2 , etc.

(4) Heavy noble gas atoms may change the electronic state of matrix encapsulated AnXn molecules because of the near-degeneracy of the multitude of different valence states. (5) Remarkable self-organizing patterns are obtained for poly-actinoyls forming extended networks somewhat different from the poly-oxo-metallates of group-6 transition elements. Some popular rules of atomic orbital occupation (p2-) must be applied with some caution.

8 1957

Magnetic properties of actinide complexes: a theoretical approach

Hélène Bolvin

Laboratoire de Chimie et Physique Quantiques

Abstract: The calculation of properties of open-shell 5f molecules is a challenge for the methods of quantum chemistry : these complexes have many low lying configurations, spin-orbit effects are important and correlation effects must be taken into account. The SO-CASPT2 method gives results that compare well to experimental data : it is a two-step wave function based method. The multiconfigurational nature of the wave functions is described by starting with a CASSCF calculation, correlation effects are calculated by 2nd order theory and spin-orbit effects are introduced in the very last step by a state interaction procedure. The first principle calculation of the magnetic properties of actinide complexes is one hand a helpful tool for the interpretation of the experimental data and on the other hand, permits the calculation of the parameters of the model Hamiltonian. We will show by several examples how calculations have become a complementary tool to the experimental data in order to get information about the nature and the magnetization of the ground and excited states. - calculation of EPR parameters : the ground state and excited states of actinyl complexes depend strongly on the nature of the equatorial ligands. All calculations are rationalized using a model based on crystal field theory. - calculation of magnetization of single molecule magnets : complexes of U(III) show a blocking of the magnetization. - determination of the parameters for paramagnetic NMR : the presence of a paramagnetic atom modify the NMR spectrum bringing informations about the structure and the bonding in the complex. Two mechanisms contribute to the shift : the contact shift results from the spin polarization while the pseudocontact shift is due to the direct interaction with the anisotropic magnetic properties of the paramagnetic ion. The latter becomes important in the case of heavy elements. The analysis of the experimental measurements and our calculations permit to distinguish between the two mechanisms.

9 1959

Local Approach to Isotropic and Anisotropic Magnetic Interactions in Copper Oxides

A.M. Pradipto, R. Maurice and R. Broer

Theoretical Chemistry, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands

Abstract: Many transition-metal containing materials exhibit fascinating phenomena, leading to important technological applications. Among the most important properties are those arising from magnetic effective interactions, which are governed by the interactions between the unpaired spins, which are essentially localized on the transition-metal ions. Their isotropic interactions lead to the “parallel” or “antiparallel” alignments of the spins, these are the so-called ferromagnetic and antiferromagnetic interactions, respectively. Due to relativistic effects such as spin-orbit coupling, the spin moments can also interact anisotropically. This type of interactions has been found to be responsible, for instance, for the so-called weak ferromagnetism. Also, the discovery of ferroelectricity in materials with spin-spiral magnetic ordering added to the importance of magnetic anisotropy in materials, with a special focus on the Dzyaloshinskii-Moriya interactions. Nevertheless, quantum mechanical studies of magnetic anisotropy have so far been rather limited. This is in part related to the difficulties in extracting the anisotropic interaction parameters as defined in phenomenological spin Hamiltonians. Another reason is that density functional theory has important limitations for treating anisotropic magnetic couplings. Therefore, the use of accurate wave function based treatments accounting for electron correlation and relativistic effects is more attractive. For extended systems like solids, the application of such methods is however not trivial. In our approach, embedded cluster models are used, where only a small part of the material is fully treated quantum mechanically. The first step of the calculations consists in determining complete active space self-consistent field (CASSCF) wave functions, which is adequate for treating near-degeneracy electron correlation, but that cannot fully include dynamical correlation. An approximate but efficient way to remedy this is to use second-order perturbation theory, as is done in the CASPT2 approach; a more accurate but also more costly route is to use Difference Dedicated Configuration Interaction (DDCI). DDCI is especially well suited to compute the small energy differences between states with different spin couplings. Our approach allows us to obtain the lowest energy states in embedded clusters, use these to calculate the isotropic and the spin-orbit-coupling driven anisotropic magnetic interactions in solids and unambiguously obtain the corresponding interaction parameters. The methods will be illustrated with studies of CuO and LiCu2O2.

10 2017

Analyzing the Interplay Between Local and Global Symmetries in molecular chemistry

Pere Alemany

Departament de Química Física, Universitat de Barcelona

Abstract: One of the main procedures used in modern chemistry in order to synthetize large molecules with complex architectures has been the assembly, either in a sequential or concerted process, of smaller building blocks. The success of this type of synthetic procedures has lead to completely new fields of chemistry such as that of hybrid organic-inorganic compounds or metal-organic frameworks that have received a great attention in the last years mainly due to their complex properties inherited in part from their building blocks. From the point of view of symmetry, this modular assembling procedures lead sometimes to amazingly complex structures with an overall low symmetry in which local fragments reminiscent of the different building blocks retain practically all of their symmetry. In this communication we will show how the formalism of continuous symmetry measures may be efficiently applied to analyze to which degree different sets of atoms retain local symmetries when assembled in a larger molecule or a supramolecular system with a different global symmetry. Using selected examples from different fields of chemistry, encompassing inorganic, organometallic, organic or even biological chemistry we will illustrate some of the most relevant consequences of this interplay between local and global symmetries in molecular chemistry. We will show that continuous symmetry measures, besides providing an elegant way of describing molecular symmetry in a way complementary to the classical group theoretical approach, allow a deeper understanding of symmetry and its consequences in modular structures obtained from the assembly of prebuild fragments. Besides the obvious geometrical symmetry of the nuclear arrangement, we will show that continuous symmetry measures can be successfully applied to the analysis of other aspects of molecules especially relevant to chemistry such as the electron density, where the remaining local symmetry of the individual building blocks may influence its global features. Special emphasis will be made for systems with incompatible local symmetries, for example collinear rotation axes of incommensurate order in sandwich complexes such as (C6H6)M(C5H5), showing how the local symmetry of one part of the molecule progressively changes till it is converted to a different local symmetry.

11 2020

New Measures of Dynamic Electron Correlation in Terms of Natural Orbitals and Their Occupancies

E. Matitoa,b,*, Eloy Ramos-Cordobab Mauricio Rodriguez-Mayorgab,c and Pedro Salvadorc a)IKERBASQUE, Basque Foundation for Science, Bilbao, Euskadi, 48011, Spain b)Faculty of Chemistry. University of the Basque Country UPV/EHU and Donostia International Physics Centre (DIPC), Donostia, Euskadi, 20080, Spain c)Department of Chemistry and Institut de Química Computacional i Catàlisi (IQCC), Girona, Catalonia, 17071, Spain. *email: [email protected]

Abstract: The concept of electron correlation goes back as far as 1934 [1], to the early stages of quantum- mechanics methods development, before the advent of coupled-cluster (CC), complete active-space self-consistent field (CASSCF) or density functional theory (DFT) methods. Initially it was defined as the energy difference between the exact result and that obtained with a Hartree-Fock wavefunction [2]. Soon enough, many different nuances of electron correlation were suggested. In fact, the computational lexicon now includes terms such as dynamic, static, angular, radial, short-range or long-range correlation [3], which are used on a routine basis. For instance, his nomenclature is often employed to decide the most convenient computational tool to accurately reproduce the properties of a given system. For instance, a CASSCF calculation introduces nondynamic correlation, while CC includes mainly dynamic correlation effects. In addition, the distinction between different electron correlation regimes can be used to identify key components missing in current density functional expressions. In this talk we present new means to quantify some of these electron correlation signatures using natural orbitals and their occupancies. In particular, we present two simple expressions to account for dynamic electron correlation employing natural orbitals and their occupancies [5]. These expressions will be used in conjuction with the almost idempotency index, which measures nondynamic correlation effects, to quantify extent of electron correlation effects in a variety of molecules and a simple model system with tunable electron correlation commonly known as harmonium of Hooke's atom [6]. These new indicators might prove useful in the context of natural orbital functional theory (NOFT), where the introduction of dynamic electron correlation effects remains a difficult problem [4]. [1] E. Wigner and F. Seitz, Phys. Rev. 46, 509 (1934). [2] P.-O. Löwdin, Adv. Chem. Phys. 2, 207 (1959). [3] D. Cremer, Mol. Phys. 99, 1899 (2001). [4] M. Piris and J. Ugalde, Int. J. Quant. Chem. 114, 1169 (2014). [5] E. Ramos-Cordoba, P. Salvador, E. Matito (submitted). [6] J. Cioslowski, E. Matito, J. Chem. Theory Comput. 7, 915 (2011)

12 2025

Recent Progress and Remaining Challenges in Electrostatics

Elena Bichoutskaia

School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD UK

Abstract: There are many instances in everyday life where small particles can acquire an electrical charge of the same sign. Examples include aerosol and water droplets in clouds, dust particles in space, toner particles in ink-jet printers, and suspensions of colloidal particles. As the particles carry a charge of the same sign, either positive or negative, they are expected to repel one another; however, under certain circumstances (and very often!) their interaction can be strongly attractive. For conducting particles, this effect was identified by William Thomson (later Lord Kelvin) who in 1845 developed a theory showing that the attraction is due to differences in the magnitude of the image charge induced in pairs of particles where either their size or charge differs. Until recently there was no stable solution to the fundamental problem of calculating the electrostatic interaction between charged particles of dielectric material, mainly due to significant mathematical complexity of the problem. To date a variety of solutions have been offered, many of which present mathematical derivations with limited applicability, numerical complications or poor convergence at short particle separations. The authors developed a comprehensive theory [1,2] with universal relevance to the electrostatic properties of closely interacting dielectric particles each carrying an arbitrary amount of charge [3-5]. In this talk, the developed theory will be discussed and integrated across multiple disciplines. Acknowledgments: ERC Consolidator grant is gratefully acknowledged. [1] E. Bichoutskaia, A. L. Boatwright, A. Khachatourian, A. J. Stace, J. Chem. Phys. 133 (2010) 024105. [2] A. Khachatourian, H.-K. Chan, A. J. Stace, E. Bichoutskaia, J. Chem. Phys. 140 (2014) 074107. [3] A. J. Stace , A. L. Boatwright, A. Khachatourian, E. Bichoutskaia, J. Coll. Interface Sci. 354 (2011) 417. [4] A. J. Stace, E. Bichoutskaia, Phys. Chem. Chem. Phys. 13 (2011) 18339. [5] A. J. Stace, E. Bichoutskaia, Soft Matter 8 (2012) 6210.

13 2026

A chemical (bonding) perspective on phase-change and related materials

Richard Dronskowski

Chair of Solid-State and Quantum Chemistry RWTH Aachen University Aachen, Germany

Abstract: Phase-change materials (PCMs) are widely used for data storage and in other functional devices. Despite their often seemingly simple compositions, these materials exhibit intriguing microscopic complexity and a portfolio of fascinating physical properties. From a more chemical perspective, the technological success of PCMs is a simple consequence of the structural and electronic peculiarities on the atomic scale and, in particular, of their bonding nature. In fact, the chemical bonding of crystalline and amorphous PCMs and also related materials is truly worth studying, now so easily done using state-of-the-art density-functional theory and properly chosen projection techniques as implemented in the Lobster program suite. In addition, finite-temperature properties of such solid-state materials are almost routinely accessible using quasiharmonic theoretical methods from first principles. By doing so, structure-property relationships at zero Kelvin and beyond may be thoroughly analyzed for crystalline and amorphous bulk-like PCMs as well as for surfaces structures, including their oxidation products and chemically related chalcogenides.

14 2028

Concepts of effective states of atoms in chemical substance and fundamentals of core pseudopotential theories

A.V. Titov, Yu.V. Lomachuk, L.V. Skripnikov, A.V. Zaitsevskii, N.S. Mosyagin, A.N. Petrov B.P. Konstantinov Petersburg Nuclear Physics Institute, Gatchina, Leningrad district, Russia; Department of Physics, Saint Petersburg State University, Petrodvoretz, Russia; Chemistry Dept., M. Lomonosov Moscow State University, 1-3 Vorob'evy Gory, Moscow, Russia

Abstract: A new method of circumscribing and evaluating the effective electronic states of ``atoms-in- compounds'' (AiC) [1] and properties of molecules and solids described by the operators heavily concentrated in atomic cores or most sensitive to variation of electronic densities in the atomic cores is discussed. Among these properties (AiC properties) are hyperfine structure, time reversal (T) and space parity (P) nonconservation effects [2], chemical shifts of X-ray emission [3] and Mössbauer lines, etc. An advantage of the approach is that a good quantitative agreement of predicted and experimental data can be attained and it is correct from the quantum mechanical point of view. The common feature of AiC properties (leading contributions from tails of valence orbitals in atomic cores) can be well- exploited and new concepts such as density matrices reduced on the radial quantum numbers for evaluating AiC properties, effective AiC configuration and partial-wave charges can be introduced. Such reduction utilizes the property of proportionality of valence and low-lying virtual spinors (W- spinors) within an atomic core region with radius Rc. Another problem that can be considered in some sense as ``adjoined’’ one to calculation of the AiC properties is economical evaluation of chemical, spectroscopic etc. properties, which are determined by the wavefunctions in the valence regions localized between atoms. The most efficient (economical) way to study such properties is to apply the pseudopotential (PP) theory [4] to exclude the atomic core electrons from explicit consideration. Such approach is most applicable to heavy-atom systems, when relativistic effects should be taken into account along with the electron correlation ones. It is shown that the radially-local (semi-local) relativistic PP theory can also be constructed on the basis of the proportionality property discussed above when satisfying the ``hardness’’ condition for the PP components in the core region. However, for the most accurate versions of the radially-local PPs they should satisfy the requirement of their ``physicity’’ in the valence region, out of Rc (or absence of unphysical interaction in the valence region that is closely related to the shape-consistent / norm-conserving PP formulations). This work is supported by the grant of Russian Science Foundation #14-31-00022. [1] А.V. Titov, Yu.V. Lomachuk, L.V. Skripnikov, Phys. Rev. A 90, 052522 (2014); L.V. Skripnikov, A.V. Titov, arXiv:1503.01001, ibid, Phys. Rev. A, (2015). [2] A.V. Titov, N.S. Mosyagin, A.N. Petrov, T.A. Isaev, D.P. DeMille, Progr. Theor. Chem. Phys. B 15, 253 (2006); L.V. Skripnikov, A.V. Titov, J. Chem. Phys. 142, 024301 (2015). [3] Yu.V. Lomachuk, А.V. Titov, Phys. Rev. A, 88, 062511 (2013). [4] A.V.Titov, N.S.Mosyagin, Int.J.Quantum Chem., 71, 359 (1999); N.S.Mosyagin, A.V.Zaitsevskii, A.V.Titov, Int.Rev.At.Mol.Phys., 1, 63 (2010).

15 2041

Magnetic properties of 4f- and 5d-metal complexes with redox-active ligands: non-perturbative account of spin-orbit coupling

Nina P. Gritsana,b, Elizaveta A. Suturinab, Alexey Dmitrieva,b a Institute of Chemical Kinetic and Combustion of SB RAS, Novosibirsk, Russia b Department of Physics, Novosibirsk State University, Novosibirsk, Russia

Abstract: Magnetic properties of molecular compounds are of high interest in the development of new advanced functional materials. The new molecular materials open up a broad prospect for future applications due to combining their inherent properties, such as ductility and transparency, with magnetic ones. The analysis of the experimental magnetic data for molecular materials (in particular, materials based on metal complexes with organic ligands) is a challenging task. In recent years, the quantum chemistry is increasingly being used to predict the electronic structure of the individual paramagnetic centers as well as the interactions between them. The most difficult task is to correctly predict the electronic properties and low-energy spectra of 5d- and 4f-metal complexes exhibiting fundamentally important relativistic effects. In this project, the explicitly correlated CASSCF and CASPT2 (or NEVPT2) approaches with non- perturbative account of spin-orbit coupling have been applied to calculate the electronic structure and low-energy spectra of the paramagnetic metal complexes. Spin-orbit coupling was accounted using the mean-field approximation (SOMF) [1]. The scalar relativistic effects were taken into account using standard second-order relativistic Douglas-Kroll-Hess Hamiltonian (DKH2). Magnetic properties of the 4f-metal complexes were calculated using the CASSCF/SO-RASSI/SINGLE-ANISO procedure [2]. Note, that until now magnetic properties of 4f-matal complexes continue to be calculated neglecting the spin-orbit coupling [3]. The report will present and discuss the results of calculations for several types of complexes, namely, rhenium complexes with non-innocent redox-active dioxolene and o-diimine ligands as well as samarium and ytterbium complexes with redox-active thiadiimide-type ligand. All these magnetically active materials have been recently synthesized and characterized by single-crystal X-ray diffraction and magnetic susceptibility measurements in a wide temperature range. In some cases, the EPR or UV- vis solution spectra have been also recorded. The authors are grateful to the RFBR (project 15-03-03242) for financial support. 1. D. Ganyushin, F. Neese, J. Chem. Phys., 138, 104 (2013). 2. L.F. Chibotaru, L. Ungur, L. J. Chem. Phys., 137, 064112 (2012). 3. G. Nocton, C.H. Booth, L. Maron, et al., Organometallics, 33, 6819 (2014).

16 2045

Chemical Bonding Analysis and Materials Design for Energy-Related Materials

Taku Onishi

Department of Chemistry for Materials, and The center of Ultimate Technology on nano-Electronics, Mie University, Japan

Abstract: Chemical bonding rule can be applicable to investigate chemical bonding character from obtained molecular orbitals. Previously, the chemical bonging characters on conductive lithium, oxide ion and proton were characterized from chemical bonding rule. In lithium ion-conducting perovskite-type titanium oxide, it was concluded that lithium ion forms ionic bonding. It was demonstrated the thermally stable perovskite-type manganese fluoride exhibits the high lithium ion-conductivity. As the alternative to lithium ion-battery, sodium ion-battery has been much expected, from the viewpoint of its safety and cost. It was discovered that our designed sodium ion-conductor exhibits the high sodium ion-conductivity. It is well known that proton conductor is utilized for electrolyte of solid oxide fuel cell (SOFC). In proton-conducting perovskite-type electrolyte, it was concluded that proton forms covalent bonding with oxygen, and chemical bonding change occurs. Recently, we have performed chemical bonding analysis for helium containing clusters. The new calculation results will be also introduced. [1] T. Onishi, Adv. Quant. Chem. 64, 31-81 (2012). [2] T. Onishi, Adv. Quant. Chem. 70, 31-67 (2015). [3] T. Onishi, Int. J. Quant. Chem. 109, 3659-3665 (2009). [4] T. Onishi, Int. J. Quant. Chem. 112, 3777-3781 (2012). [5] T. Onishi, T. Helgaker, Prog. Theor. Chem. Phys. 27, 233-248 (2013). [6] T. Onishi, QSCP-XIX; J. Chin. Chem. Soc. (Taipei), in press.

2059

Plasma electrolytic oxidized coatings on aluminum and titanium: composition, structure, properties

Elena A. Koblova a,b, Oleg L. Shcheka b, Alexander Yu. Ustinov a,b

(a) Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia, (b) Far Eastern Federal University, Vladivostok, Russia

Abstract: A wide range of metal oxide coatings, formed by the method of plasma electrolytic oxidation (PEO) on aluminum and titanium, has been studied using X-ray photoelectron spectroscopy. Besides the base metal, these coatings contain various amounts of nickel and/or copper, and other components depending on the composition of the electrolyte and the features of formation. The atomic composition of the surface and subsurface layers, chemical states of the elements and some structural features have been determined. As follows from the obtained results, the basis of the PEO-coatings is aluminum (titanium) oxide and various oxides of nickel and/or copper. The appropriate investigations showed that PEO-coatings possess a big variety of physical and chemical properties, including catalytic activity in the conversion of CO to CO2. Obviously, these properties are related to the structural features of the coatings. In order to clarify this, quantum chemical calculations of model systems have been performed using the density functional theory, hybrid functional B3LYP and split valence basis sets 6-31+G*, 6- 311+G*. According to the obtained by XPS results, the structural fragments of the coatings have been studied in cluster approach. First of all, clusters of (Al2O3)n, n = 1 – 8 were calculated and the most energetically preferable of them have been used to study the adsorption of CO in order to ascertain some aspects of such interaction. Also, calculations of other components of PEO-coatings, such as nickel and copper oxides have been performed by means of (NiO)n, n = 1 – 12 and (CuO)n, n = 1 – 4, 6, 8, 16 clusters. Energetic and electronic characteristics of these clusters have been determined as well as the optimal geometric features and some aspects of their interaction with CO. Finally, the calculations of the multicomponent metal oxide systems have been carried out. The optimal geometric parameters of bare MiAl2O4 and MAl3O6 clusters, where M = Ni or Cu, and some clusters doped with hydrogen that model the surface of PEO-coatings have been studied. The optimal position and the most active centers for CO interaction have been determined. The results of our study will be discussed in the present communication.

18 2064

Tackling Electronic Excited States in Complex Surroundings.

Xavier Assfeld Theory-Modeling-Simulation, Université de Lorraine, France

Abstract: Most of time hybrid Quantum Mechanics/Molecular Mechanics (QM/MM) calculations are carried out with the help of non-polarizable force field. This is generally a well-accepted approximation if one recall that force field point charges are often defined to reproduce condensed phase properties. Thus, one can say that the MM point charges are implicitly already polarized in average. This is true and accurate only if the quantum part does not vary too much during the studied chemical process. Electronic excited states can have very different nature than the electronic ground state. One can think for example of excited states with a marked charge transfer character. In these situations, the approximation defined above does not hold any longer. Hence, to correctly treat excited states with any QM/MM method, the polarization of the surrounding is mandatory. In this lecture, I will present a recent development that can be considered as an “universal” force field that is shortly described in the following. For the UV/Visible absorption of molecules in the gas phase, the Franck-Condon principle is very often invoked. It states that, the electronic reorganization during an electronic transition being so fast compared to the nuclear motion, the molecular geometry can be considered fixed. In solution, the geometry of the chromophore is still considered unchanged during the absorption process, but the internal geometry of solvent molecule and their relative orientations also. A contrario, the electrons of the solvent molecules can react instantaneously to the modification of the electronic cloud of the chromophore. This is called the electronic response of the surrounding (ERS). A solvent is generally an isotropic media, in average, that can be modeled by a polarizable continuum characterized by the relative dielectric constant with separated electronic and nuclear contributions. Hence, extracting the electronic contribution is trivial in so called self-consistent reaction field approaches (SCRF). Oppositely, macromolecules need an atomic description using QM/MM methods. Instead of using polarizable force fields, we propose a simple method which combines hybrid QM/MM techniques with SCRF approaches to evaluate the ERS in macromolecules. This method will be detailed and applied to the interpretation of the photophysics of some biological systems. Special attention will be devoted to the light switch effect and to DNA photosensibilization. [1] Jacquemin, D.; Perpète, E. A.; Laurent, A. D.; Assfeld, X.; Adamo, C. Phys. Chem. Chem. Phys. 11 (2009) 1258-1262. [2] Laurent, A.; Assfeld, X. Interdisciplinary Sciences: Computational Life Sciences, 2 (2010) 38–47. [3] Monari, A; Rivail, JL; Assfeld, X. Accounts of Chemical Research 46(2) 2013 596-603

19 Oral Contributions

1962

Effects of parity and time-reversal symmetry violation in diatomics.

A.D. Kudashov, L.V. Skripnikov, A.N. Petrov, N.S. Mosyagin, A.V. Titov

Saint Petersburg State University, Saint Petersburg, Russia (SPbSU) National Research Centre "Kurchatov Institute" B.P. Konstantinov Petersburg Nuclear Physics Institute, Gatchina, Russia (NRC "Kurchatov Institute" PNPI)

Abstract: One of the most exciting topics in modern science is the search for new physics, i.e. phenomena beyond the Standard model (SM), and many attempts have been made to discover these phenomena in molecular experiments (1,2) searching for effects associated with breaking of the spatial inversion symmetry (P) and time-reversal symmetry (T). Certain fundamental characteristics, which represent the P- and T-nonconservation phenomena can be discovered and studied in low-energy experiments with heavy-atom molecules rather than in high-energy studies on accelerators like LHC. They are the anapole nuclear moment, the Schiff nuclear moment, the electron electric dipole moment (eEDM), etc. The hopes are that at least some of these characteristics will turn out to have greater values then the SM predicts, lending credit to some of its numerous extensions. For example, great progress has been achieved in case of ThO, with the experiment yielding the most stringent constraint on eEDM to date (2). In turn, the measured nuclear anapole moment value of the Cs nucleus (3) is in contradiction with other data on the Cs nucleus (4), which may warrant further investigation of this phenomenon. A major problem of all such experiments is the impossibility of a direct measurement and reliance on a priori theoretical knowledge of certain atomic and molecular parameters, linking the measured values with fundamental characteristics. The computational results regarding the sensitivity of such diatomics as RaO and RaF to measurements of the P- and T,P-odd effects are presented. The calculations were carried out within the two-step method combining relativistic correlation calculations of valence electronic structure using generalized relativistic effective core potential approach followed by the non- variational restoration of four-component electronic structure in the vicinity of a heavy atom (5). This work is supported by the SPbSU Fundamental Science Research grant from Federal Budget No. 0.38.652.2013 and RFBR Grant No. 13-02-01406. [1] J. S. M. Ginges and V. V. Flambaum, Phys. Rep. 397, 63 (2004). [2] J. Baron, W. C. Campbell, D. DeMille, et al. (ACME Collab.), Science 343, 269 (2014). [3] C. S Wood, S. C. Bennett, D. Cho, B.P. Masterson, J. L. Roberts, C.E. Tanner, C. E. Wieman, Science 275, 1759, (1997). [4] W. R. Johnson, M. S. Safronova, U. I. Safronova, Phys. Rev. A 67, 062106 (2003). [5] A. V. Titov, N. S. Mosyagin, A. N. Petrov et al., PTCP B 15 (2006) 253.

1965

Electron transitions in rippled and twisted graphenes

L.G. Bulusheva1,2, O.V. Sedelnikova1,2, V.O. Koroteev1, A.L. Chuvilin3, A.V. Okotrub1,2 1Nikolaev Institute of Inorganic Chemistry, SB RAS, 3 Academician Lavrentiev ave., Novosibirsk 630090, Russian Federation 2Tomsk State University 36 Lenina Ave., Tomsk, 634050, Russian Federation 3CIC NanoGUNE, Donostia-San Sebastian 20018, Basque Country, Spain Abstract: Rippling of graphene monolayer or rotation of a layer relative to another one may substantially change the electron density distribution as compared to the perfect graphene. Here, we study such effects using density functional theory (DFT) calculations of periodic models and experimental optical and electron energy loss (EEL) spectra of corresponding objects. Electronic ground-state band structure of graphene models was obtained using plane-wave self-consistent field formalism in the local density approximation as implemented in the Quantum-ESPRESSO code. Dielectric function of a model was calculated within the random phase approximation. The rippled graphene models had armchair or zigzag edge and different height of the out-of-plane bending. Calculations showed that periodic graphene deformation results in a localization of the electronic density on the top and bottom parts of the wave-like structure and creates conducting channels along the wave crest [1]. Positions of the absorption peak and plasmons calculated for the flat graphene agreed well with the experimental values showing validity of the single-particle picture for investigation of the dielectric response in graphene- based systems [2]. Analysis of interband transitions demonstrated a contribution of electron transitions being forbidden for the flat graphene in the in-plane and out-of-plane components of dielectric function of rippled graphene. We showed that positions and shape of plasmons are very sensitive to the geometry of rippled models [3]. Stressing the graphene mechanically or placing the layer on an artificial substrate one could control the graphene rippling constructing a material with optical properties adjusted for a certain application. Using the EEL spectra and calculations of twisted bilayer graphene (BLG) models, we showed that plasmonic properties of BLG are governed by a stacking pattern. As compared to graphene monolayer, the spectra of rotationally faulted BLG samples exhibit additional low-energy features, and the peak energies systematically shift with changing the rotation angle.. The interaction between twisted layers is strongly nonhomogeneous resulting in spatial localization of plasmon excitations that opens new possibilities for engineering of graphene plasmonics. [1] O.V. Sedelnikova, L.G. Bulusheva, A.V. Okotrub «Modulation of electronic density in waved graphite layers” Synth. Metals 160 (2010) 1848-1855. [2] O.V. Sedelnikova, L.G. Bulusheva, I.P. Asanov, I.V. Yushina, A.V. Okotrub «Energy shift of collective electron excitations in highly corrugated graphitic nanostructures: Experimental and theoretical investigation” Apl. Phys. Lett. 104 (2014) 161905. [3] O.V. Sedelnikova, L.G. Bulusheva, A.V. Okotrub “Ab initio study of dielectric response of rippled graphene” J. Chem. Phys. 134 (2011) 244707.

1967

Electronic and magnetic properties of the fluorinated graphenes

A.V. Okotrub1, L.G. Bulusheva1, I.P. Asanov1, T.L. Makarov

1Nikolaev Institute of Inorganic Chemistry, SB RAS, 3 Academician Lavrentiev ave., Novosibirsk 630090, Russia 2Lappeenranta University of Technology, FI-53851 Lappeenranta, Finland

Abstract: The structure and composition of graphite fluorides are determined by the synthetic conditions, namely, crystallinity and particle size of pristine graphite, reaction temperature, and fluorinating agent and two stoichiometric compounds with CF and C2F composition are known. A layer of the graphite fluoride CF consists of trans-linked cyclohexane chairs in which sp3-hybridised carbons combine with fluorine atoms by covalent bonds. Incorporation of two kinds of carbon atoms, linked with fluorine atoms and bare carbon, into graphite fluoride C2F could give the various structures within a C2F composition. Here, from the comparison of the experimental NEXAFS spectrum of graphite fluoride C2F produced at room temperature and theoretical spectra plotted for three different models we show that the more preferable fluorine pattern is the formation of zigzag-like CF chains [1-3]. The models were calculated within density functional theory at the B3LYP/6-31G level. CK-edge NEXAFS spectrum was simulated using the so-called (Z+1)-approach, where a fictitious Z+1 compound with an additional proton in its atomic nucleus is introduced instead of the real Z compound containing a core level hole. The applicability of this approach to the graphite fluorides was previously tested for the CF compound. Recent measurements revealed magnetic properties for the fluorinated graphene [4] and graphite fluorides [5]. With the purpose to find origin of the magnetic ordering we calculated the models where polyene carbon chains were created in a fully fluorinated graphene fragment. Two parallel zigzag- or armchair-type chains with a length varied from 2 to 7 atoms were located in a center of the fragment. B3LYP calculations showed that models with even-numbered chains are more preferable energetically.The model with a single polyene odd-numbered chain showed an anti-ferromagnetic ordering. Our calculations show that the exchange spin interaction decreases with the separation of the bare carbon atoms and thus one could expect ferromagnetic or anti-ferromagnetic ordering in the fluorinated graphene depending on the atomic structure and stoichiometry of a layer. [1] A.V. Okotrub, et al., «Anisotropy of Chemical Bonding in Semifluorinated Graphite C2F Revealed with Angle-Resolved X-ray Absorption Spectroscopy» // ACS Nano. 2013. V. 7. P. 65-74. [2] I. P. Asanov, et al., Graphene nanochains and nanoislands in the layers of toom-temperature fluorinated graphite, Carbon, 59, 518–529 (2013). [3] A. Vyalikh, et al., Fluorine patterning in room-temperature fluorinated graphite determined by solid- state NMR and DFT, J. Phys. Chem. C 117, 7940/7948 (2013). [4] R.R. Nair, et al., ”Spin-half paramagnetism in graphene induced by point defects” Nat. Phys. 1 (2012) 1-4. [5] T.L. Makarova, et al., “Structural evolution and magnetic properties of underfluorinated C2F” J. Supercond. Nov. Magn. 25 (2012) 79-83.

1978

Ambivalent reactivity of acetylenes in the presence of superbase: a quantum-chemical insight

N.M. Vitkovskaya*, V.B. Kobychev*, E.Yu. Larionova**, V.B. Orel*, A.D. Skitnevskaya*, B.A. Trofimov*** *Irkutsk State University, 1 Karl Marx Str., 664003 Irkutsk, Russia, **East-Siberian Institute of the MIA of Russia, 110 Lermontov St., 664074 Irkutsk, Russia, ***A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1 Favorsky Str., 664033 Irkutsk, Russia

In the presence of bases, acetylene and its derivatives can react as either an electrophilic substrate (vinylation reactions) or nucleophilic RCC– agent (ethynylation reactions). Such a two-sided nature of acetylene reactivity is particularly stressed in the superbase media like a KOH suspension in dimethyl sulfoxide. In the conception of this kind of superbase catalysis we introduce a non-dissociated KOH is suggested to be the active center, and the DMSO surrounding provides a sufficient loosening of the K+OH– ion pair. The KOH coordination shell contains up to five DMSO molecules, though a simplified model with a single molecule of the solvent was found to provide a reasonable description for the base-catalyzed acetylene reactions with both electrophiles and nucleophiles. Vinylation of alcohols, thiols, oximes, pyrroles and ketones with acetylene and its alkyl- and aryl derivatives was widely investigated within the ab initio and DFT approaches. The whole conversion cycle including active nucleophile generation, addition of the latter to the acetylene moiety yielding an intermediate carbanion, and the final product formation accompanied by the catalyst regeneration could be realized in the KOH immediate coordination shell. The lowest activation barriers in the range of 10-15 kcal/mol are attributed to vinylation of thiols that occurs at a room temperature, while the highest ones of ca 30 kcal/mol correspond to oximes vinilation that needs heating up to 110 C to reach at least 40% yield. By contrast, ethynylation of ketones needs only small activation energy from 2.3 kcal/mol for acetone to 6.7 kcal/mol in the case of acetophenone. Thus, a tertiary alcohols formation becomes preferable at a room temperature, while the most thermodynamically favorable ketone vinylation faces the activation barrier of 15-25 kcal/mol. Indeed, an unexampled reaction of alkyl-, cycloalkyl-, aryl- and hetarylketones nucleophilic addition to phenylacetylene in the presence of superbase under heating was recently reported [1]. A two-sided reactivity of acetylene is strongly pronounced in its reactions with water. A sequential vinylation-ethynylation-vinylation reaction becomes the most favorable pathway of the acetylene reaction with H2O yielding the product of a hydrative trimerization, 2-vinyloxy-1,3-butadiene [2]. This work was supported by a project part of Government Assignment for Scientific Research from the Ministry of Education and Science, Russia (№4.1504.2014/К) and grant No. 15-03-03880 by the Russian Foundation for Basic Research. [1] Trofimov B.A.; Schmidt E.Yu., Zorina N.V., Ivanova E.V., Ushakov I.A. J. Org. Chem., 2012, 77, 6880. [2] Vitkovskaya N.M., Larionova E. Yu., Skitnevskaya A.D., Trofimov B.A. Tetrahedron Lett., 2015, 56, 1063.

1986

Computational study of complexes of Lewis acids with inorganic benzene analogs: Stability and reactivity

A.Y. Timoshkin, A.S. Lisovenko

Institute of Chemistry, Saint Petersburg State University, University pr. 26, Saint Petersburg, Russia

Abstract: Inorganic heterocycles, such as borazine and its derivatives, are isoelectronic to benzene and are believed to have some degree of aromaticity. Formation of low reactive borazine and polyborazines upon thermal destruction of ammonia borane BH3NH3 limits its practical application as hydrogen carrier due to recharging problems. It is suggested, that activation of borazine and polyborazines can be achieved by disruption of conjugated pi-system by complex formation. Results of extensive computational DFT studies of complexes of group 13 Lewis acids and Lewis bases (ammonia, pyridine) with borazine [1], substituted borazines [1], polyborazines [2], and their aluminum and phosphorus analogs [3] will be presented. Factors, affecting stability and reactivity of these complexes will be evaluated. In particular, mechanism of the experimentally observed H/D exchange of tribromborazine in deuterobenzene in presence of AlBr3 [4] will be discussed. Complexes with Lewis bases are not stable; but triple complexes which feature both Lewis acid and Lewis base, are predicted to be viable [1]. It is shown that complex formation reduces endothermicity and significantly lowers the barrier for the hydrogenation of borazine [1] and polyborazines [2]. This opens perspective for the convenient regeneration of the spent hydrogen fuel based on ammonia borane. This work was supported by St. Petersburg State University grants 12.38.255.2014 and 12.50.1563.2013. Research was carried out using computational resources provided by Resource Center "Computer Center of SPbU" [1] Lisovenko A. S., Timoshkin A. Y., “Donor-Acceptor Complexes of Borazines”, Inorg. Chem., 2010, 49, 10357-10369. [2] Lisovenko A. S., Timoshkin A. Y., “Quantum chemical studies of hydrogenation of borazine and polyborazines in the presence of Lewis acids”, Russ. Chem. Bull., 2012, 61, 897-905. [3] Lisovenko A. S., Timoshkin A. Y., Russ. J. Gen. Chem. 2011, 81, 831-839. [4] Timoshkin A.Y., Kazakov I.V., Lisovenko A.S., Bodensteiner M., Scheer M., Inorg. Chem., 2011, 50, 9039–9044.

1987

Hydrogen-Release Mechanisms in Tetramer of Lithium Amidoborane

Pomogaeva A. V.*, Morokuma K.**, Timoshkin A. Y.*

* Inorganic Chemistry Group, Institute of Chemistry, St. Petersburg State University, University Pr. 26, Old Peterhof, St. Petersburg, 198504, Russia ** Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan

Abstract: Usage of solid-state hydrogen storage materials can solve many problems related to storage, transportation and utilization of H2. Alkaili-metal amidobaranes have attracted considerable attention as environmentally friendly, safe and stable hydrogen storage materials. Lithium amidoborane (LiNH2BH3, LiAB) is found to be an excellent hydrogen source which release 10.9 wt% of H2 at relatively low temperature.[1] Computational study of the LiAB dimer dehydrogenation[2] indicates that energetically favorable intermolecular hydrogen release pathway can lead to formation of triangular Li-H-Li complex in transition state (TS). Solid-state hydrogen release mechanisms are still a challenge for computational chemistry. Here we suggest a systematic study of dehydrogenation of LiAB tetramer as the first step toward investigation of condensed phase hydrogen release mechanisms. Global reaction rout mapping (GRRM) strategy[3] allows automated search of all possible reaction pathways in the particular molecular system. Applying GRRM methodology for the LiAB tetramer, artificial force was applied to B and N atoms of different molecules in the tetramer. Potential energy surface was calculated within DFT M06/6-31(p) approximation. Minimization of the force-stimulated energy surface provided approximated TSs those were optimized with 6-311(p,d) basis set and related pathway was determined. Various approach directions between reactants provided a great number of possible pathways. The most favorable pathways are found to be leading to NH2BH2 release with formation of intermolecular T-shaped Li3H complex followed by polymerization. The next step included applying the artificial force to the hydrogen atom in LiH involved in this T-shaped Li3H complex toward each N atom in the molecular aggregate. Charge redistribution caused by neighboring Li atoms makes this LiH to be extremely active moiety in the process of dehydrogenation. Indeed, the TS leading to the H2 release, which is the rate-determining step in the initial dehydrogenation, is found to be lower than the step for the dimer on the analogous pathway involving formation of Li-H-Li complex. Comparison of possible pathways toward hydrogen release in the LiAB stresses the importance of the intermolecular processes in the condense phase. This work was financially supported by grant of Russian Science Foundation (project №14-13-00151). [1] Z. Xiong, et al Nature Materials, 7 (2008) 138 [2] D. Y. Kim, et al Chem. Eur. J. 15 (2009) 5598 [3] S. Maeda, et al Phys. Chem. Chem. Phys. 15 (2013) 3683

1988

What relativistic quantum chemistry can give to the search for a new physics?

L.V. Skripnikov, A.N. Petrov, A.V. Titov 1) National Research Centre “Kurchatov Institute” B.P. Konstantinov Petersburg Nuclear Physics Institute, Gatchina, Leningrad district 188300; 2) Department of Physics, Saint Petersburg State University, Petrodvoretz 198504, RUSSIA.

Abstract: A nonzero value of permanent electric dipole moment of electron (eEDM) implies manifestation of interactions which are not symmetric with respect to both spatial and time inversions (P,T-odd interactions). The observation of the eEDM at a level significantly greater than 10-38 e*cm would indicate the presence of a New physics beyond the standard model; popular extensions of the standard model predict the magnitude of eEDM at the level of 10-26 10-30 e*cm [1]. In 1970th it was shown that diatomic molecules containing heavy elements are very promising for such experiments. In the systems one can achieve a strong effective electric field (Eeff) acting on unpaired electrons that leads to the enhanced effect. However, the interpretation of the experiments in terms of eEDM requires knowledge of the magnitude of Eeff, which cannot be measured, and is the task of relativistic quantum chemistry. We have developed a method, which allows to significantly simplify the relativistic treatment of heavy- atom compounds. It can be used for calculation of properties such as Eeff, hyperfine structure constants, etc. in atoms, molecules and crystals. This approach includes relativistic correlation calculation of valence electronic structure using generalized relativistic effective core potential approach followed by the non-variational restoration of four-component electronic structure in the vicinity of heavy atom nucleus. We present here the status and application of the method to the most actual molecules to search for the New physics. Among the systems are ThO [3] molecule on which the best limit on eEDM is obtained by ACME collaboration: eEDM < 8.7x10 -29e*cm [4]. The limit can be used to estimate restriction on the masses of intermediate supersymmetric particles, which can be involved to induce eEDM [4]. The 229ThO molecule can be used to search for P,T-odd nuclear magnetic quadrupole moment of Th [5]. For interpretation of such experiment, we have calculated corresponding parameters. Also we discuss other prospective systems such as ThF+ which is considered by E. Cornell group for the eEDM measurement. This work is supported by the SPbU Fundamental Science Research grant from Federal Budget No. 0.38.652.2013 and the RFBR Grant No. 13-02-01406. L.S. is also grateful to the President of RF grant no MK-5877.2014.2 and Dmitry Zimin "Dynasty" Foundation. [1] E. D. Commins, Adv. At. Mol. Opt. Phys. 40, 1 (1998); [2] A.V. Titov, N.S. Mosyagin, A.N. Petrov, T.A. Isaev, D.P. DeMille, Progr. Theor. Chem. Phys. B 15, 253 (2006). [3] L.V. Skripnikov, A.N.Petrov, A.V. Titov J. Chem. Phys. 139, 221103 (2013) [4] J. Baron, et. al. ACME collaboration Science 343, 269 (2014) [5] L.V. Skripnikov, A.N. Petrov, A.V. Titov, V.V. Flambaum, Phys. Rev. Lett. 113, 263006 (2014).

1993

Effect of an external electrostatic field on the electronic transitions in small CdS clusters

Aliya Assilbekova

L.N. Gumilyov Eurasian National University, Astana, Kazakhstan

Abstract: Colloidal quantum particles (quantum dots) have been in the scientific focus for about thirty years with constantly increasing knowledge of the properties and possible applications of these new materials. Using the method of time-dependent density functional theory DFT [1,2] the effect of the external electrostatic field on the electronic transitions in CdS quantum dots of small size was investigated. For 4+ 4+ calculations hexagonal clusters [Cd4S2] and [Cd4S(SH)2] [3,4] were reviewed. Direction of vector of the electric field strength is chosen so as to reduce or increase the value of dipole moment vector. 4+ For a cluster Cd4S2] in case of small values of the external field the maximum increase and decrease of the dipole moment can be seen, but these fields are not strongly affect the absorption spectra. And application of strong electric fields can lead to blue shift of λ1 values (the computed wavelength of the 4+ transition of lowest-energy). However, applying a large external field for the cluster [Cd4S(SH)2] long-wavelength transitions of low intensity were observed. [1] Bauernschmitt R., Ahlrichs R. Treatment of electronic excitations within the adiabatic approximation of time dependent density functional theory. Chem. Phys. Lett. – 1996. – Vol. 256. – P. 454-464. [2] Furche F., Ahlrichs R. An improved method for density functional calculations of the frequency- dependent optical rotation. J. Chem. Phys. – 2002. – Vol. 117. – P.7433-7447. [3] Rockenberger J., Troger L., Kornowski, A., Vossmeyer T., Eychmuller A., Feldhaus J., Weller H. EXAFS Studies on the Size Dependence of Structural and Dynamic Properties of CdS Nanoparticles. J. Phys. Chem. B – 1997. – Vol. 101. – P. 2691-2701. [4] Banerjee R., Jayakrishnan R., Ayyub P. Effect of the Size-Induced Structural Transformation on the Band Gap in CdS Nanoparticles. J. Phys.: Condens. Matter – 2000. – Vol. 12. – P. 10647–10654.

1996

Hyperfine and Zeeman Interaction in diatomics for electron electric dipole moment search

A.N. Petrov, L.V. Skripnikov, and A.V. Titov

National Research Centre “Kurchatov Institute” B.P. Konstantinov Petersburg Nuclear Physics Institute, Gatchina, Leningrad district 188300; Department of Physics, Saint Petersburg State University, Petrodvoretz 198504, RUSSIA.

Abstract: One of the most intriguing fundamental problems of modern physics is the search for a permanent electric dipole moment (EDM) of elementary particles [1]. Polar molecules have a number of advantages over atoms for electron EDM searches, including a larger effective internal electric field (Eeff), and resistance to a number of important systematics, these are the factors which determine the sensitivity limit for the electron EDM experiment. The understanding the g-factor dependence on electric fields is vital for understanding possible systematic effects in polar molecule-based electron EDM searches [2]. We show that precise calculation of g-factors requires accounting for subtle effects such as hyperfine and nonadiabatic interactions [3]. In turn the knowledge of the hyperfine structure is essential for estimating the size of the theoretical uncertainties for the Eeff that can not be measured. The latter value is required for interpretation of the results of planned experiments in terms of EDM. Besides we show that the diatomics with hyperfine structure may have advantages for measuring the electron EDM. The first advantage comes from the larger Eeff being applied to the electron at a given external electric field as compared to the diatomics with spinless nuclei. The second advantage comes from the fact that difference between g-factors for the omega-doublet levels can be converged to zero for some electric field [1]. The goal of the report is to review our latest studies for heavy-atom diatomics - ThO, PbO, PbF, YbF - which are of real interest for current experiments to search the electron EDM. Particular attention is devoted to ThO. Combination of the spin precession measurement of ThO [4] with the calculated Eeff [5] leads to the most rigid limit on EDM: |de| < 8.7x10 -29e*cm This work is supported by the SPbU Fundamental Science Research grant from Federal Budget No. 0.38.652.2013 and the RFBR Grant No. 13-02-01406. L.S. is also grateful to the President of RF grant no MK-5877.2014.2 and Dmitry Zimin "Dynasty" Foundation. [1] A.V. Titov, N.S. Mosyagin, A.N. Petrov, T.A. Isaev, D.P. DeMille, Progr. Theor. Chem. Phys. B 15, 253 (2006) [2] A.N. Petrov, L.V. Skripnikov, A.V. Titov, N.R. Hutzler, P.W. Hess, B.R. O’Leary, B. Spaun, D. DeMille, G. Gabrielse, and J.M. Doyle, PRA 89 (2014) 062505 [3] A. N. Petrov, Phys. Rev. A 83, 024502 (2011). [4] J. Baron, et. al. ACME collaboration Science 343, 269 (2014) [5] L.V. Skripnikov, A.N.Petrov, A.V. Titov J. Chem. Phys. 139, 221103 (2013)

2021

Pressure in electronically excited warm dense metals: Density functional theory analysis

Vladimir V. Stegailov, Petr A. Zhilyaev

Joint Institute for High Temperatures RAS, Moscow 125412, Russia

New emerging science is connected with formation of warm dense matter (WDM) at the initial transient state of material evolution after energy deposition into electron subsystem with electron temperatures Te in the range 1-100 eV. Usually WDM forms in ultrafast phenomena and is a non- equilibrium state that makes it very challenging for theory, modelling and simulation (e.g. [1]). In many cases WDM can be described as a two-temperature (2T) system when electron and ion subsystems can be considered in quasi-equilibrium at Te > Ti. Both in continuum and in atomistic models it is assumed that the quasi-equilibrium 2T-WDM can be described using thermodynamic concepts. In this work on examples of Al and Au we are making an attempt to analyze the electronic contribution to the total pressure in 2T-WDM. Another question considered is the separation of electrons into bound and free. We perform finite temperature Kohn-Sham density functional theory (FT KS DFT) calculations in the pw basis with PAW potentials. We analyze the dependencies on the electronic temperature of the electronic pressure Pe components for fcc aluminum and gold for Te = 0–12 eV. We see the strongest dependence on Te in the kinetic and non-local pressure components. Using the pDOS-based analysis we decipher the bond hardening effect in fcc Au [2] as a transition of electrons from d-like states into s- and p-like states as well as into the plane-wave like (i.e. free) states. We deploy the comparison of the Fermi gas model with the FT KS DFT results to understand the 2T- WDM properties better. We also consider the Hellmann-Feynman forces acting on ions in 2T-WDM. We are making the following conclusions [3]. The sum of kinetic and non-local DFT pressure components governs the build-up of the electron pressure in FT KS DFT models of warm dense metals. The non-local component of the electron-ion interaction plays an important role in the changes of warm dense metal properties with increase of Te.

In the general case the increase of Te in warm dense metal not only causes the free-electron pressure build-up, but also changes the effective interionic forces [1] and hence the binding pressure and the equation of state.

Using effective ion-ion potentials obtained by force-matching for different Te [1] it is possible to separate the binding component of electron pressure and the free electron like component. This is a method (among several others [4]) for calculation of the number of free electrons, i.e. the ionization degree of WDM. [1] G. Norman, S. Starikov, V. Stegailov, JETP. 114, 792 (2012) [2] V. Recoules et al., Phys. Rev. Lett. 96, 055503 (2006) [3] P. A. Zhilyaev, V. V. Stegailov, Contrib. Plasma Physics, 55, 164-171 (2015) [4] G. Norman, I. Saitov, V. Stegailov, P. Zhilyaev, Phys. Rev. E. 91, 023105 (2015)

2030

Optical Chemosensor Properties of Europium(III) chelates. Quantum chemical calculations

Emelina T.B., Mirochnik A.G.

Institute of Chemistry FEBRAS, Vladivostok, Russia

Abstract: Intensive investigations in the field of development of polyfunctional materials characterized by optical chemosensor properties are currently observed. The promising compounds for the production of optical chemosensors are particularly lanthanide-containing complexes. Features of the Eu(III) photochemical behavior allows registering fine changes of the coordination sphere of a rare-earth ion upon surrounding impact. We developed a Eu(III) ion based sensor for detection of ammonia in atmosphere. Ammonia is highly toxic gas, it is used in chemical industry and in industrial refrigerator systems. Аmmonia monitoring in the environment constitutes an urgent task. We suggest the europium(III) сhelate (Eu(Dbm)3) complex adsorbed on silica gel as an ammonia sensor. Density functional theory calculations were performed using the GAMESS program system. The hybrid B3LYP density functional was employed. The ECP52MWB basis set with 52MWB pseudopotential was used for Eu atom, and appropriated MWB basis sets were used for light atoms. The initial geometrical parameters were taken from the experimental data and then were fully optimized. As we have established experimentally, the action of ammonia vapor on Eu(Dbm)3 yields the 1.5-10- fold increase of the Eu(III) luminescence intensity. To clear the mechanism of ammonia influence on luminescence intensity of Eu(III), quantum chemistry calculations of the system Eu(Dbm)3•H2O – ammonia were performed.

In accordance with our calculations, the H2O molecule is held in the coordination sphere of Eu(III) due to the hydrogen bond with the oxygen atom of Dbm. When the ammonia molecule approaches the complex Eu(Dbm)3•H2O, a strong H2O•NH3 bond is formed, and the hydrogen bond of H2O molecule with Dbm ligand disrupts. The formed complex H2O•NH3 could leave the europium coordination sphere, and the free site can be occupied by the other NH3 molecule. In this case, the complex energy stabilizes, as compared to its aqueous analog (by 0.2 eV), while the formed Eu-NH3 bond is strong and of a covalent character.

The comparative analysis of luminescent behavior Eu(Dbm)3•H2O and Eu(Dbm)3•NH3 complexes was able to explain the reasons of Eu(III) luminescence intensity increase. The energy diagram of Eu(Dbm)3•NH3 complex was created. We found that main channel of intramolecular energy transfer 5 from ligand to Eu(III) is preferably T*→ D0, which is completed by the radiative relaxation of the excited state.

2036

Similarities between amorphous and microcrystalline forms of hydrogenated silicon from periodic DFT modeling of IR spectra

Andrey A. Rybakov, Alexander V. Larin

Department of Chemistry, Moscow State University, Leninskie Gory, Moscow, GSP-2, 119992 Russia

Abstract: Vibrational Si-H frequencies were calculated on the basis of density functional theory (DFT) using periodic boundary conditions for N-Si voids, N < 8, in microcrystalline hydrogenated silicon (MHS) and (100), (110), and (111) slabs of 8, 5, and 8 layers, respectively, with the dangling bonds being saturated with hydrogen atoms. The slabs are considered as the models of inter-grain boundaries (IGB) in MHS. The N-Si voids of different shapes have been obtained via random deleting N silicon atoms. It was shown that the high stretching modes (HSM) of Si-H vibrations, which are usually assigned to SiHX, appear also due to (SiH)X groups, X = 2 - 4, in the N-Si voids. No such (SiH)X groups were formed with X > 1 at the IGB. The low stretching modes (LSM) are thus assigned to Si-H groups presented at both N-Si voids and IGB. Similar relative stability of the voids is obtained with two different DFT approaches, i.e., B3LYP with atomic basis set and PBE with plane wave basis set. The formation of these (SiH)X groups is the consequence of tetrahedral Si symmetry of MHS and can be the result of a conservation of local ordering in AHS [1]. The presence of similar (SiH)X groups in the voids of amorphous hydrogenated silicon (AHS) explains macro concentration of H…H pairs separated by 1.8 Å [2] according to NMR data (1019 – 1020 cm-3). Such H…H pairs were obtained in di- vacancies of AHS but the authors mentioned that it is not typical for higher size vacancies [3]. At the absence of the evidences of dominant concentration of di-vacancies this result can be considered as additional confirmation of the local ordering in AHS [1] and closer similarity between the vacancies in MHS and AHS. [1] Larin A.V., Milyaeva D.V., Rybakov A.A., Bezrukov D.S., Trubnikov D.N., Mol. Phys., 112, 956 (2014). [2] D.C. Bobela, T. Su, P.C. Taylor, and G. Ganguly, J. Non-Cryst. Solids, 352, 1041 (2006). [3] S. Chakraborty, D.A. Drabold, Physical Review B 79, 115214 (2009)

2038

Calculation of energy transfer parameters in the photoactive complex of europium by multireference quantum-chemical methods

Kurbatov, I.A.1 Freidzon, A.Ya.2,4 Kharchenko, V.I.1,3 Cherednichenko, A.I.1,3 Taidakov I.V.5 1 Far Eastern Federal Universtity, ul. Suhanova 8, Vladivostok, Russia, 2 Photochemistry Center, RAS, ul. Novatorov 7a, Moscow, Russia, 3 Institute of Chemistry of the FEB RAS, ul. 100-letiya 159, Vladivostok, Russia, 4 National Research Nuclear University Moscow Engineering Physics Institute, Kashirskoe shosse 31, Russia, 5 Lebedev Physical Institute RAS, Leninskii pr. 53, Moscow, Russia

Trivalent lanthanide (Ln(III)) coordination compounds are promising phosphorescent emitters. They can be used in a number of high-tech devices: organic light emitting diodes (OLEDs), displays, optical amplifiers, lasers and fluorescent panels. Furthermore, some Ln(III) complexes exhibit triboluminescence, i.e., emission that occurs under crystal cracking, which makes them promising as new molecular sensors capable to detect damage and defects. The electronic spectra of Ln(III) ions originating from f-f transitions in the inner 4f-shell are individual for each ion. Possibility of generating monochromatic radiation is an important advantage of Ln(III) compounds. It is known that the best luminescence efficiency of Ln(III) is achieved when the donor triplet level of the ligand (antenna) is resonant with the accepting excited level of Ln(III). On the other hand, the accepting level should lie higher than the emitting level to avoid fast back-transfer of energy decreasing the emission efficiency. Therefore, selection of the ligands most appropriate for each ion is a top priority in the photochemistry of lanthanides at present. In order to describe the mechanism of the energy transfer during photoexcitation of antenna ligand and calculate the constants of the energy transfer steps, the positions of the lowest excited singlet and triplet levels in the chelate complex [Eu(Pyr)4]– (Pyr = 1,3-bis(1,3-dimethyl-1H-pyrasol-4-yl)-1,3- propanedione) were calculated by XMCQDPT/CASSCF method taking into account relaxation of the complex in the excited states. The active space included one highest occupied molecular orbital and one lowest unoccupied molecular orbital of each ligand (CASSCF (8,8)). The structures of the ground and excieted-states were optimized by CASSCF; the energies of the singlet and triplet states in the obtained geometries are calculated by CASSCF and refined by XMCQDPT methods. Stuttgart 4f-in- core quasi-relativistic pseudopotential with the corresponding basis set was used for the lanthanide ion, and 6-31G(d,p) basis set was used for the light atoms. All the calculations were performed by FireFly software package. The calculations show that the singlet (light-induced) and triplet (electrogenerated) excitations of the complex are a π-π* ligand-localized excited states. Initially, photoexcitation results in the singlet excited state of the ligand, in which its structure is severely distorted. The energy transfer takes place 5 from the ligand triplet state (2.65 eV) to the nearest level of Eu(III), D1 (2.36 eV). In the experimental 5 7 fluorescence spectrum, the most intense band corresponds to the D0- F2 transition of Eu(III). This favorable level alignment explains high emission intensity observed in this complex.

2043

Tuning the spin crossover phenomenon through fine control of nitrogen positions on imidazol-diazine Fe(II) complexes

Eduardo G. R. de Arruda1,2, Alex Domingo1,*, Quan Phung1, André L. B. Formiga2, Kristine Pierloot1

1) Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Heverlee- Leuven, Belgium 2) Institute of Chemistry, University of Campinas - UNICAMP, P.O.Box 6154, 13083-970, SP - Brazil

Abstract: The spin crossover (SCO) phenomenon can induce a switch between two electronic states of different spin multiplicity under some external stimuli (i.e. temperature, pressure). Ideally, that process will show hysteresis and lead to a bistable material with potential technological applications. However, designing such materials with those specific properties devised beforehand requires a deep understanding and control over the multiple variables in play (i.e. molecular structure, environment, cooperative effects). Transition metal complexes based on Fe(II) are prime examples of the SCO phenomenon that offer remarkable spin transitions at relatively high temperatures. We synthesized various Fe(II) complexes with the 2-(1H-imidazol-2yl)diazine class of ligands, which combine a π- acceptor (diazine) and a σ-donor (imidazole) moieties. Such mix of properties on a single ligand offers the potential to control the ligand field strength on the metal centre and thus, tune the relative stability of the spin-states involved in the SCO phenomenon. Small modifications of the imidazole–diazine ligand structure can lead to a substantial change in the properties of the complex. The alteration of the diazine moiety from a pyrazine to a pyrimidine, solely differing in the relative position of two N atoms, leads to a loss of various features in their absorption spectra and the appearance of a spin-transition at 100 K. These prominent effects on the molecular properties by such a small structural change reflect the underlying complexity of the phenomenon. Therefore, we applied the complete active space second-order perturbation theory (CASPT2) to obtain an accurate description of the electronic structure of both compounds. The evaluation of the spin-state energetics at the CASPT2 level show that the position of the N atoms in the diazine moiety can control the spin of the ground state of the complex, turning from a low-spin singlet to a high-spin quintet. In relative terms, the energy difference between the low- and high-spin states is rather small, totalling less than 10 kcal/mol. Due to such small quantities, we took special care with the so-called core correlation effect, which we found to be determinant in the correct evaluation of spin-state energetics with the CASPT2 method. Moreover, we calculate the front of the metal to ligand charge transfer band, which is responsible for the changes observed in the absorption spectra of the compounds.

2044

Thermal Decomposition of High-Energy Compounds: New Insights from High-level ab initio Calculations

Vitaly G. Kiselev, Dmitry E. Mashkantsev, and Nina P. Gritsan

Novosibirsk State University, Russia and Institute of Chemical Kinetics and Combustion SB RAS, Novosibirsk, Russia

Abstract: Kinetics and mechanism of thermal decomposition are crucial for understanding the sensitivity and performance of energetic species. Modern high-level quantum chemical calculations are a very powerful tool for obtaining quantitative data and understanding tiny details of kinetic mechanisms. Here we present two typical cases: thermolysis of 1,1-diamino-2,2-dinitroethylene (DADNE, FOX-7), which is among the most promising high-performance insensitive energetic compounds; and furazano- tetrazine-dioxide (FTDO), which is, in turn, a very sensitive species with a very high content of energy. The reactions typical of nitroalkanes and nitroarenes (viz., C-NO2 bond dissociation, nitro-nitrite, and nitro-aci-nitro isomerization) have been widely discussed as possible primary channels of thermal decomposition of FOX-7. Moreover, the chemical mechanism of initiation of this species is often simply related to the “weakest” or “trigger” bond C-NO2. However, the highly accurate CCSD(T)-F12 computations revealed that none of conventional reactions dominate the thermolysis of FOX-7. On the contrary, we proposed the two competing primary reaction channels never discussed before. The rate- limiting step of FOX-7 thermolysis is the H-transfer (enamino-imino tautomerization) with a gas-phase activation barrier ~48 kcal/mol followed by radical decomposition. Only a slightly higher overall activation barrier (~55 kcal/mol in the gas phase) was found for the second channel comprised of intramolecular cyclization to oxazete-N-oxide, which is prone to fast subsequent molecular decomposition. We also found the proposed decomposition mechanism to be relevant in the case of triaminotrinitrobenzene (TATB), another insensitive high-energy compound widely used in applications. The activation barriers of the two above discussed decomposition pathways and nitro- nitrite rearrangement are very close to each other (~62 kcal/mol). On the other hand, multireference calculations (CASSCF/NEVPT2) revealed the crucial role of biradicoloid open-ring intermediates in the thermolysis mechanism of FTDO. The primary reaction channel comprises a tetrazine ring opening followed by subsequent recyclization to a 5-membered ring and elimination of nitric oxide with an effective activation barrier of ~31 kcal/mol. In this case, widely used DFT methods yield entirely spurious results.

2046

A general interface for computational chemistry and applications

Fernando Ruettea, Alexander Perazaa, Morella Sáncheza,b, Marbelia López. aLaboratorio de Química Computacional, Centro de Química, Instituto Venezolano de Investigaciones Científicas (IVIC). bIUT Federico Rivero-Palacio, Caracas, Venezuela.

Abstract: Developing a generic graphic interface system for free codes is of great importance for improving the usability of Computational Chemistry (CQ) and Computational Physics (CF) programs in education and in applications to solve scientific and technological problems. In this talk we will show the development and application of an interface for CQ (IVIChem) [1,2] for building molecules in 2D and 3D, assemble input files and facilitate analysis of the results for a series of codes. Also, here interfaces for designing and making the components of the main interface (an interface for building other interfaces) will be presented. The emphasis of this work is to develop a free software-based CQ and CF interface, in order to have a free tool that can be useful for development of scientific and technological researches, primarily for research groups with few resources. Examples of departure are shown for the computational packages: GAMESS, DeMon2k, DeMon-nano, MOPAC and CATIVIC. As future IVIChem, we consider forming a community of development to broaden the spectrum of use in different areas of CQ and CF to improve its computational architecture. It requires well defined schema, format, and style of programming that will facilitate the readability of the code and enable good interaction between programmers. Thus with the ideas of reuse code and separation of concepts, the task of developing new applications and subsequent maintenance is facilitated. Object-oriented programming is implemented, hierarchical model view controller (HMVC) using the framework of PHP (Laravel), employing suitable database, including a variety of software in different subareas of CQ and CF and development and analysis results for each. Agile methodology is used, considering also free programs for improving interface´s scientific visualization with the help of the international community. Some applications and research examples are presented, using this interface. [1] V. Sojo, A. Peraza, F. Ruette, M. Sánchez, E. Acosta, J. Comput. Methods Sci. Eng. 12 (2012) 397. [2] M. Sánchez, A. Peraza, V. Sojo, E. Matheus, E. Coto, M. Fernández, R. López, M. López, F. Ruette, Rev. Procesos Quím. 6 (2012) 35.

2053

Structure of genuine and conjugate Fermi holes in two-electron systems and its applications for correlation problems

Tokuei Sako Nihon University

Abstract: Fermionic nature of electrons yields versatility of electronic structure and electronic properties of matter. Electrons with the same spin cannot occupy the same spatial position. This nature gives the two electrons sharing the same spin well-known standard or genuine Fermi holes in their triplet wave function in a multi-dimensional coordinate space satisfying r1 being equal to r2. In the case of the two electrons with opposite spins, on the other hand, there seems to be little or at least not so commonly known about the existence of such a hole in their singlet wave function. This is the so-called conjugate Fermi hole [1, 2], that exists in a multi-dimensional coordinate space in the vicinity of the genuine Fermi hole but satisfying r1 being not equal to r2, and whose existence is irrespective of the electron- electron interaction and is determined purely by the orbital configuration of the relevant electronic state. In the present study we clarify first the conditions for which conjugate Fermi holes exist and their nature and characteristics by referring to those for the counterpart genuine Fermi holes. Then, as applications of this conjugate-Fermi-hole concept the origin of the first Hund rule [1, 2] and also the origin of the anomalously strong angular correlation [3] both in the singlet-triplet pair of states in singly-excited series of He and He-like atomic ions (He-like systems) have been rationalized on the basis of the structure of the genuine and conjugate Fermi holes in the internal space of two-electron systems. The first rule of so-called Hund’s rules empirically derived by F. Hund in the pre-quantum mechanics era has shown to be almost universally valid not only for atoms but also molecules and artificial atoms or quantum dots (See references in [1]). The mechanism of this fundamental atomic-physics rule to operate in most of finite quantum systems has been pursued for more than three quarters of a century but the debate about its origin still persists mainly because of a lack of precise knowledge about the wave functions of the relevant spin states. Only with the idea of standard Fermi holes in the triplet wave function the origin of this rule might seem mysterious but with the idea of conjugate Fermi holes in the counterpart singlet wave function its origin can be rationalized easily. A similar situation happens for the anomalously strong angular correlation that appears for the (1s)(2p) configuration of the He-like systems in the large limit of nuclear charge where the electron correlation must be practically zero [3]. Appearance of this anomalous angular correlation can also be understood as a manifestation of the genuine and conjugate Fermi holes. [1] T. Sako et al., Phys. Rev. A 83, 032511 (2011). [2] T. Sako et al., J. Phys. B 45, 235001 (2012). [3] T. Sako, et al., Phys. Rev. A 89, 062501 (2014).

2057

High pressure alkali subhalides: Insights into their chemical bonding and rationalization of their stability

Gabriele Saleh, Artem R. Oganov

Moscow Institute of Physics and Technology, 9 Institutskiy Per., Dolgoprudnyi, Moscow Region, 141700, Russia

Abstract: The application of high pressure (hundreds of GigaPascal) to materials, besides modifying their properties, changes dramatically their reactivity. Because of that, new compounds were discovered which escape the well-established chemical paradigms of ambient pressure chemistry. The development of predictive, physically-rooted models to rationalize the newborn field of high pressure chemistry is of utmost importance. Nevertheless, a convincing explanation for most of these phenomena is still lacking. An example of counterintuitive chemical phenomena taking place under pressure is the recent discovery [1] of Sodium Subchlorides NaxCl (x=1.5, 2, 3) formation. We have carried out a thorough study of these compounds as well as of other alkali subhalides by means of evolutionary crystal structure prediction calculations (USPEX approach [2]) combined with an in dept analysis of their crystal and electronic structure. The latter involves the use of real space approaches (such as the topological analysis of charge density and Electron Localization Function) together with the examination of the Density Of States, including its orbital components and the distribution of charge density associated to valence bands. Moreover, we discovered the phase diagram of NaxCl to be richer than previously thought, for it includes 1 new compound, Na4Cl3, and other 2 previously undiscovered thermodynamically stable high-pressure phases of Na3Cl. The results of our investigation, presented in this contribution, are twofold. First, we demonstrate the appearance of peculiar chemical phenomena in high pressure Sodium Subchlorides. Examples are the coexistence of metallic and ionic bonds in the same compound and the formation, at very high pressure, of crystal structures where Chlorine atoms, in an oxidation state of -2, form an extended network of bonds through the occupation of their d-orbitals. More importantly, we derive a set of rules which enable one to rationalize the stability of alkali subhalides at high pressure. The predictive ability of our model is demonstrated by the results of crystal structure prediction calculations carried out on high pressure alkali subhalides A3Y (A=Li, Na, K; Y=F, Cl, Br). We found that Lithium and Sodium subhalides follow the same trend as NaxCl, thereby confirming the predictive ability of our model. Potassium subhalides, instead, displays a somewhat different behavior. We demonstrate how this difference is due to the participation of K d-orbitals into chemical bonding and the significant K- halogen hybridization, especially for K3Cl. Finally, we show how the rules derived for light alkali subhalides are applicable to the results of recent investigations on similar high pressure compounds appeared in literature. [1] Zhang W. W.; Oganov A.R. et al. Science (2013) 342, 1502. [2] Oganov, A. R.; Glass, C.W. J. Chem. Phys. (2006) 124, 244704.

2058

DFT modeling of the catalytic CO oxidation on the Ni-Al metal oxide surface formed via plasma electrolytic oxidation

Elena A. Koblova a,b, Sergey E. Malykhin c, Alexander Yu. Ustinov a,b

(a) Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia, (b) Far Eastern Federal University, Vladivostok, Russia, (c) Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia

Abstract: Plasma electrolytic oxidation (PEO) of aluminum and 3d-metals allows to produce metal oxide coatings which possess various attractive physical and chemical properties including catalytic activity in CO to CO2 oxidation [1]. X-ray photoelectron spectroscopy method applied to the particular system reveals that the top layer is represented mainly by alumina oxide and some oxidized nickel compounds. According to our data, the most probable Ni-Al oxide structure which is considered here seems to be NiAlO4 spinel. To study the features of the catalytic activity of the formed metal oxide PEO-coatings, together with the experimental investigation, the theoretical one has been carried out within the Gamess US code [2]. Cluster model for the DFT quantum-chemical study of the CO oxidation is suggested and some aspects of the oxidation mechanism is discussed. According to our view, formate and carbonate species are formed during the reaction over Ni-Al oxide catalyst. Reaction of the CO adsorbed on Ni2+ 3+ 2+ ion with H2O on the adjacent Al ion is found to produce HCO radical on Ni which is then migrates to nearby O2- ion to form surface formate group. The subsequent scissoring of the C-H bond results in CO2 formation. Details of the DFT simulated chemical process will be discussed in the present communication. [1] Lukiyanchuk I.V., Tyrina L.M., Rudnev V.S., Ustinov A.Yu., Nedozorov P.M., Vasileva M.S. Kinetics and Catalysis, 2008, 49(3) 439-445. [2] Schmidt M.W., Baldridge K.K., Boatz J.A., Elbert S.T., Gordon M.S., Jensen J.H., Koseki S., Matsunaga N., Nguyen K.A., Su S., Windus T.L., Dupuis M., Montgomery J.A. J. Comput. Chem, 1993, 14(11) 1347-1363.

2068

Development of highly accurate approximate scheme for computing the charge transfer integral

Anton Pershin, Peter G. Szalay

Laboratory for Theoretical Chemistry, Institute of Chemistry, Eotvos Lorand University, Budapest, Hungary

Abstract: The charge transfer integral is a keystone parameter required by various theoretical models to describe charge transport properties, e.g. in organic semiconductors. The accuracy in computing this important property depends on several factors, which include the level of electronic structure theory and internal simplifications of the applied formalism. The goal of this work is to identify the performance of various approximate approaches as well as to estimate the role of electronic structure theory level in computing the charge transfer integral. First, by using the high level Equation-of-Motion Coupled Cluster theory for the electronic structure, we studied the changes of the parameter over different spatial perturbations of ethylene dimer, which was estimated with several widely used models. Here, it was shown that, while both Energy Split in Dimer (ESD) and Fragment Charge Difference (FCD) methods were equivalent with the exact formulation for symmetrical displacements, they are less efficient when describing transfer integral along the asymmetric alteration coordinate. Since the “exact” scheme was found computationally expensive, we examined the possibility to obtain the asymmetric fluctuation of the transfer integral by a Taylor expansion along the coordinate space. By exploring the efficiency of this novel approach, we showed that the Taylor expansion scheme represents an attractive alternative to the “exact” calculations due to a substantial reduction of computational costs, when a considerably large region of the potential energy surface is of interest. Moreover, we demonstrated that the Coupled Cluster and MBPT(2) approaches are the methods of choice for performing the benchmark calculations of the value, in contrast to some recently published results, which was tested on 7 different pi-stacked molecular dimers. We showed that a proper treatment of the involved ionized states, achieved by applying the continuum orbital strategy, decreases an error in computing the transfer integrals relative to MRCI+Q data by one order magnitude, which in case of CC2 method corresponds to the value deterioration from 39.9 to 3.8 %. We also extended the application of the continuum orbital strategy to the TDDFT method, and observed that it led to a dramatic improvement of the ionized states description to the conventional TDDFT approach, characterized by the error lowering from 209.0 to 24.5 %.

Posters

1906

Non-empirical prediction of the photophysical and magnetic properties of systems with open d- and f-shells based on combined Ligand Field and Density Functional Theory (LFDFT)

Fanica Cimpoesu, Harry Ramanantoanina, Benjamin Herdem, Werner Urland and Claude Daul

Computational Chemistry Lab, University of Fribourg / Switzerland

Abstract: Despite the important growth of ab initio and computational technics, ligand field theory in molecular science or crystal field theory in condensed matter offers the most intuitive way to calculate multiplet energy levels arising from systems with open shells d and/or f electrons. We developed this last decade a ligand field treatment of inorganic molecular modelling taking advantages of the dominant localisation of the frontier orbitals within the metal-sphere. This feature, being observed in any inorganic coordination compounds especially if treated by Density Functional Theory calculation, allows the determination of the electronic structure and properties with a surprising good accuracy. In ligand field theory, the theoretical concepts consider only a single atom centre; and treat its interaction with the chemical environment essentially as a perturbation. Therefore success in the simple ligand field theory is no longer questionable, while the more accurate molecular orbital theory does in general over-estimate the metal-ligand covalence, thus yields wave functions that are too delocalized. Although LF theory has always been popular as a semi-empirical method when dealing with molecules of high symmetry e.g. cubic symmetry where the number of parameters needed is reasonably small (3 or 5), this is no more the case for molecules without symmetry and involving both an open d- and f-shell (number of parameters is roughly 90). However, the combination of LF theory and Density Functional (DF) theory that we introduced twenty years ago can easily deal with complex molecules of any symmetry with two and more open shells. The accuracy of these predictions from 1st principles achieves quite a high accuracy (less than 5 percent) in terms of states energies. Hence, this approach is well suited to predict the magnetic and photo-physical properties arbitrary molecules and materials prior to their synthesis, which is the ultimate goal of each computational chemist. We will illustrate the performance of LFDFT for the design of phosphors that produces light similar to our sun and predict the magnetic anisotropy energy of single ion magnets.

1929

Effective Hamiltonian Crystal Field: Present Status and Applications

A.L. Tchougreeff

MSU, MCCME, IAC RWTH

Abstract: We review the fundamental basics of the Effective Hamiltonian Crystal Field (EHCF) method originally targeted for calculations of the intra-shell excitations in the d-shells of coordination compounds of the first row transition metals. The formalism of effective operators is applied to derive the explicit form of the effective operator for the dipole moment in the d-shell electronic subspace. This allows to calculate the oscillator strengths of optical d-d transitions which are otherwise forbidden when treated in the standard framework of EHCF. We also extend the EHCF methodology to describe magnetic interactions of the effective spins residing in several open d-shells of the polynuclear coordination compounds. This is a challenging task of improving the precision of ca. 1000 cm-1 (that of describing the excitation energies of single d-shells by the already well successful EHCF method) to that of ca. 100 cm-1 characteristic for the energies required to reorient the spins, i.e. eventually by an order of magnitude. This is performed within the same paradigm as in the EHCF method: the concerted usage of the McWeeny's group-function approximation and the Löwdin partition technique. These are applied to develop the effective description of the d-system. This approach is implemented and tested 4+ on a series of binuclear complexes [{(NH3)5M}2O] of trivalent cations featuring μ-oxygen superexchange paths in order to confirm the reproducibility of the trends in the series of values of exchange constants for the compounds differing by the nature of the metal ion. The results of calculations are in a reasonable agreement with available experimental data and other theoretical methods. The Effective Hamiltonian Crystal Field (EHCF) method has originally been designed to reproduce the excitations in the d-shells of coordination compounds of the first transition row, and this approach has been extended in the MagAîxTic package to magnetic interactions of the effective spins in multiple open d-shells. It is now tested on a series of binuclear Fe(III) complexes featuring μ-oxygen superexchange pathways. Good agreement with experimental values is reached either for linear or bent bridge geometries as well as for protonated bridges.

1951

Quantum-Chemical ab initio Calculations on Ala- (C5H5Al) and Gallabenzene (C5H5Ga)

Stefanie Mersmann, Halima Mouhib, Matthias Baldofski, and Gerhard Raabe*

Institut für Organische Chemie, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany

Abstract: Conventional quantum-chemical ab initio and time-dependent density functional theory (TD-DFT) calculations employing various basis sets were used to study the spatial as well as the electronic structure of ala- (C5H5Al) and gallabenzene (C5H5Ga), which might be of interest for example as ligands in organometallic chemistry. The energetically lowest closed-shell singlet states of both compounds were found to have a non-planar structure of Cs symmetry with C-X-C bond angles of about 116° (MP2/6-311++G**)and 125° (CCSD/aug-cc-pVDZ). At approximately 103°, the corresponding angles of the energetically lowest triplets are significantly smaller. The lowest triplet state of alabenzene is also non-planar (Cs) at the MP2 level while optimization with the CCSD and the CASPT2 methods resulted in planar structures with C2v symmetry. The corresponding state of gallabenzene has also C2v symmetry at all levels of optimization. The relative stabilities of the energetically lowest closed-shell singlets and the lowest triplet (ΔE(T1-S0)) states are small and their signs even strongly depend on the applied method. However, according to the highest levels of theory applied in this study the singlet states of the title compounds are slightly lower in energy than the corresponding triplets with singlet/triplet gaps between about 0.5 and 5.8 kcal/mol in favour of the closed-shell singlet states. The majority of the applied methods gave a slightly smaller splitting for the ala- than for the gallacompound. Independent of the applied method (TD-DFT/B3LYP/6- 311++G(3df,3pd)//MP2/6-311++G** or SAC-CI/6-31++G(3df,3pd)//MP2/6-311++G**) the general shapes of the calculated UV/VIS spectral curves are quite similar for the energetically lowest singlet states of ala- and gallabenzene, and the same is true for the calculated spectra of the normal modes. The calculated UV/VIS spectra of C5H5Al and C5H5Ga are featured by long wavelength bands of moderate intensity around 900 nm at the TD-DFT level and between 1300 and 1500 nm with the SAC-CI method. According to the results obtained with both methods these bands are predominantly due to HOMO(π)→LUMO(σ*) transitions. The results of isodesmic bond separation reactions for the singlet states indicate some degree of stabilization due to delocalization in both of the title compounds. With our best values between 29 and 32 kcal/mol this stabilization appears to be only slightly less than the previously reported value for borabenzene ( 5∼H385B). kcal/mol, C

1958

Nonorthogonal Approach for Intermolecular Transitions

R.W.A.Havenith, R.Broer and W.C.Nieuwpoort

Theoretical Chemistry, Zernike Institute for Advanced Materials, University of Groningen Nijenborgh 4, 9747 AG Netherlands

Abstract: The efficient quantum chemical treatment of electronic excitation in molecules can be done with well- established quantum chemical methods like CASSCF/CASPT2 or methods based on Coupled Cluster theory, depending on the importance of static electron correlation. Also (TD)DFT is a cost-effective alternative for many problems. For intermolecular electronic transitions finding an adequate first principle approach is less straightforward. The initial steps towards electron=hole separation in organic donor-acceptor blends for photovoltaic purposes are examples of such transitions. Another example from the same field is singlet fission, a process through which one photon generates two electron-hole pairs instead of one. The pairs are generated by radiationless conversion from an excited singlet state localized on one chromophore, into two excited triplet states, each on one of two neighboring chromophores, coupled to an overall singlet. Studying the efficiency of such processes requires knowledge of the potential energy surfaces, vibrational frequencies and adiabatic coupling elements. With standard methods the energies of the relevant states can be estimated, but the coupling matrix elements are not easily accessible. We propose a new approach, in which correlated molecular wave functions are obtained by multi-reference methods like CASSCF and CASCI, while the wave functions of a system containing two or more such molecules are expressed as anti-symmetrized products, AP's, of these molecular wave functions. The molecular orbitals in general optimized for each individual molecular state, leading to nonorthogonal orbitals within one AP. The nonorthogonality between the orbitals of different molecules within one AP and between the AP's makes the computations of coupling matrix elements non-trivial, but a parallelized program is currently developed. On the other hand, the interpretation of the various couplings is straightforward. The approach is illustrated with an investigation of the electronic couplings in tetracene dimers and trimers. The role of charge transfer states as intermediates in the singlet fission process in tetracene is addressed as well.

1966

Stabilization of plane basal rings in silicon pyramidal systems

O. A. Gapurenko,* V. Ya. Lee,** R. M. Minyaev,* V. I. Minkin*

* Institute of Physical and Organic Chemistry, Southern Federal University, 194/2 Stachki ave., Rostov on Don 344090, Russian Federation ** Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1–1–1 Tennodai, Tsukuba 305-8571, Ibaraki, Japan

Abstract: Pyramidal compounds have inverted bond orientation on apex atoms what attracts much attention to these non-classical systems. Pyramidane C[C4H4] is well studied theoretically but is not yet synthesized. Recently its derivatives E[C4R4] (E=Ge, Sn, R=SiMe3) have been isolated and t characterized [1] as well as the full-germanium analogue Ge[Ge4R4] (R=Si Bu2Me) [2]. Pentagonal + pyramidal system Si[C5Me5] have been known for many years [3]. DFT calculations (B3LYP/6-311+G**) were used to study silicon square and pentagonal pyramidal t systems Si[Si4R4] and Si[Si5R5] with different substituents (R=H, Me, SiH3, SiMe3, Si Bu2Me) to make clear the influence of R to plane basal ring stabilization. The smallest model compounds (R=H) with high symmetry C4v or C5v are the third and second-order saddle points, respectively. Increase in substituent size leads to their stabilization to transition state (TS) and local minimum, respectivly. In t case of Si[Si4R4] bulkier substituent Si Bu2Me reduce the energy gap between pyramidal TS and distorted minimum to 0.2 kcal/mol. Because of the very low energy barriers against this rearrangement t the pyramidal compound Si[Si4(Si Bu2Me)4] can be regarded as possessing effectively pyramidal structure. This work was supported by the Russian Foundation for Basic Research (14-03-92101), Russian Scientific Schools (NSh-274.2014.3), and by the Japanese Society for the Promotion of Science (24550038). [1] V. Ya. Lee, Y. Ito, A. Sekiguchi, H. Gornitzka, O. A. Gapurenko, V. I. Minkin, R. M. Minyaev, J. Am. Chem. Soc. 135, 8794-8797, 2013. [2] V. Ya. Lee, Y. Ito, O. A. Gapurenko, A. Sekiguchi, V. I. Minkin, R. M. Minyaev, H. Gornitzka, Angew. Chem. Int. Ed. 54, 2015, in press [DOI: 10.1002/anie.201500731]. [3] P. Jutzi, A. Mix, B. Rummel, W. W. Schoeller, B. Neumann, H.-G. Stammler, Science, 305, 849- 851, 2004.

1969

Forced oscillations of the DNA nitrous bases

L.V. Yakushevich*, L.A. Krasnobaeva**

*Institute of Cell Biophysics, Russian Academy of Sciences, ul. Institutskaya 3, Pushchino, Moscow Region 142290, Russia **Tomsk State University, pr. Lenina 36, Tomsk 634050, Russia **Siberian State Medical University, 2, Moscowski Trakt st., Tomsk, 634050, Russia

Abstract: It is well known that the DNA internal mobility is an important factor that should be taken into account in the studies of the processes occurring in the living organisms at the molecular level. Many types of internal motions are possible in the molecule. The reasons for their occurrence are considered a thermal reservoir, collisions with the "hot" molecules of the solution, interaction with external fields. In this work, we consider one of possible types of the internal motions - the angular oscillations of nitrogenous bases under the action of external periodic force. As a mathematical model, we use a system of two coupled nonlinear differential equations that imitate angular oscillations of nitrous bases in both polynucleotide chains and take into account the effects of dissipation [1]. The equations are complemented by the terms which imitate the action of external periodic force. To find analytical solutions of the model equations, we apply the method of average field that allows to reduce the system of two coupled equations to the system of two independent equations. Each of them simulates oscillations of nitrous bases of one of the two polynucleotide chains in the average potential field induced by the other chain. In the harmonic approximation, when the base angular displacements are small, we obtain the general and particular solutions of the equations. We obtain also the dispersion curves and investigate the conditions of resonance. In the nonlinear case, the model equations are solved with the help of the energy method [2]. Analytical solutions in the form of nonlinear conformational waves – kinks, are investigated. We obtain analytical formula that determines the velocity of the kinks moving along the polynucleotide chains. All calculations are made for two cases: for homogeneous sequence (poly (A)), and for the sequence of the gene coding interferon alpha 17 (IFNA17) which is known as antiviral drug. [1] L.V. Krasnobaeva, L.V. Yakushevich Rotational dynamics of bases in the gene coding interferon alpha 17 (IFNA17) // Journal of Bioinformatics and Computational Biology 2015. Vol. 13, No. 1. P. 1540002 (13 pages) [2] D.W. McLaughlin, A.C. Scott Perturbation analysis of fluxon dynamics // Phys Rev A 1978.Vol. 18, P. 1652

1973

Electronic structure of tellurium(IV) halide complexes with guanidine and cesium

A.A. Dotsenko, V.I. Vovna, V.V. Korochentsev, A.G. Mirochnik

Far Eastern Federal University

Abstract: Functional materials including inorganic anions and organic cations are used in laser technologies, optoelectronics and information technologies due to their nonlinear optical and nonlinear dielectric properties. In complex compounds with a general formula of RaMbX3b+a, where R is an organic cation, M = Te(IV) or Sb(III), X = Cl, Br, alkyl-substituted ammonium, and protonated nitrogen-containing heterocycles, guanidinium C(NH2)3 and its diphenyl-substituted typically act as cations. The growing interest in this class of compounds in the past 10-15 years is due to the discovery of ferroelectric and ferroelastic phase shifts in these materials.The unusual physical and chemical properties result from the dynamics of rotation of the organic cations, and a large number of these phase shifts is observed in some of these crystals. However, spectral luminescence properties and their correlation with the unique properties of the electronic structure in these compounds have not been fully investigated. The study of the electronic structure of this class of compounds is important because the insights gained will contribute to the development of the chemistry of p-element coordination compounds, elucidate the relationship between the luminescence parameters and the structural features of the frontier electronic levels and provide opportunities for directed synthesis of new substances with desirable properties. In this work, the electronic structure of the complex compounds of Te(IV) with protonated guanidines and cesium using XPS and DFT methods are reported. The energies and molecular orbital composition of the anions and cations based on the estimated data for modelled clusters is presented, and the XPS spectra of the valence and core electrons have been analysed. The lower excited singlet and triplet 2- 2- states of the TeCl6 and TeBr6 anion using time dependent density functional theory (TDDFT) have been calculated. The classification of the excited states taking into account spin-orbit interactions has been given in terms of the representations of double point groups. The Jahn-Teller splitting of the lower excited state of the anions based on the node characteristics of the HOMO and LUMO is discussed.

1977

Stereoselectivity of the methanol, methanthiol and ketones vinylation with substituted acetylenes in the KOH/DMSO superbasic medium: quantum chemical study

N.M. Vitkovskaya*, E.Yu. Larionova**, V.B. Kobychev*, V.B. Orel*, A.D. Skitnevskaya*, B.A. Trofimov*** *Irkutsk State University, Russ-664003 Irkutsk, 1 Karl Marx, Russia; **East-Siberian Institute of the MIA of Russia, Russ-664074 Irkutsk, 110 Lermontov, Russia; ***A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Russ-664033 Irkutsk, 1 Favorsky, Russia.

Abstract: The current advances in acetylene chemistry are largely associated with application of high basicity media. Among the latter, the KOH/DMSO system turns out to be the most universal and practical. The nucleophilic addition of alcohols, thiols and ketones to the substituted acetylenes in this system occurs with high stereoselectivity [1]. The isomerization of the carbanionic intermediates can decrease the reaction selectivity to give not only Z–isomers but also E–products of the reaction [2]. Using the approach (MP2//6-311++G**//B3LYP//6-31+G*, PCM), the selectivity of vinylation reactions in the KOH/DMSO superbasic system is provided not only by the energetic preference of the trans–structure of the transition state, but also by the possibility of E–Z–isomerization of the corresponding intermediate carbanions. The intermediate isomerization of methoxyethene, 2– methoxyprop–1–ene, and 2–methoxybut–2–ene carbanions is impossible; this favors the stereoselective course of the reaction of the methanol vinylation with prop–1–yne and but–2–yne. The kinetic possibility of isomerization of the intermediate carbanion favors the decrease in the selectivity of the methanol vinylation reaction with ethynylbenzene so that two isomeric forms of the product (Z– and E–) in 5:2 ratio are observed in reaction mixture under the experimental conditions [3]. The formation of E–products only in the vinylation reaction of ketons with arylacetylenes observed upon prolonged heating (~ 100C) due to the rotary isomerization of enolate ions, resulting from deprotonation of beta, gamma–unsaturated ketones. The activation barrier of this reaction is high (30 kcal/mol). At lower temperatures or in the case of formation of beta, gamma –unsaturated ketones which cannot give enols the ratio of E– and Z–isomers is determined by differences in the activation barriers of the isomerization (3– 13kcal/mol) and protonation carbanions which were generated at the stage nucleophilic addition. This work was supported by a base part of Government Assignment for Scientific Research from the Ministry of Education and Science, Russia (No. 2014/51, project code 206) and the RFBR grant No. 15-03-03880. [1] Trofimov B.A. Sovrem. Probl. Org. Khim., 2010, 15, p. 23. [2] N. M. Vitkovskaya E. Yu. Larionova, A. D. Skitnevskaya et al. Dokl. Chem., 2013, 452, p. 227. [3] Tarasova O.A., Mikhaleva A.I., Shmidt E.Yu. et al. Zh. Org. Khim., 1994, 30, 6, p. 807.

1980

Influence of Metal Nature on the Formation of Amidoboranes of alkali and alkaline-earth metals

A.S. Lisovenko, A.Y. Timoshkin

Institute of Chemistry, Saint Petersburg State University, University pr. 26, 198504 Saint Petersburg, Russia

Search for the solid materials with high hydrogen content and easy H2 release is an important task for the hydrogen energetics [1]. Ammonia borane NH3BH3 [2] is a promising candidate for hydrogen storage application due to its high hydrogen gravimetric density (19.6 wt %). But its thermal decomposition proceeds in two steps and requires elevated (>110оС) temperatures; undesirable side products (ammonia, borazine) are also evolved. More recently, it was shown that derivatives of ammonia borane, such as amidoboranes MNH2BH3 (M=Li-K), decompose in a single step at lower temperatures (circa 85оС) [3], ammonia and borazine were not detected. It is supposed, that such compounds may serve as catalysts for the decomposition of ammonia borane. The main goal of this work is to elucidate the influence of metal nature on the thermodynamic characteristics and activation barriers of formation of alkali and alkaline-earth metal amidoboranes M(NH2BH3)x: xBH3NH3 + MHx = M(NH2BH3)x + xH2, (x=1: M=Li-Cs; x=2: M=Be-Ba) All computations have been carried out using the standard Gaussian 03 program package [4]. Density functional theory in the framework of hybrid three-parameter exchange functional of Becke [5] with the gradient corrected correlation functional of Lee, Yang, and Parr [6] (B3LYP) with all electron def2-TZVPP basic set [7] was used throughout. All structures have been fully optimized and verified to be minima or transition states (TS) by subsequent vibrational analysis. Intrinsic reaction coordinate scans confirmed that obtained TS are connecting reactant and products. Results of quantum-chemical studies reveal, that independently of nature of the metal, reactions between alkali metal hydrides MH (M=Li-Cs) and BH3NH3 are exothermic, have very small barriers (2-6 kJ mol-1) and occur spontaneously. In contrast, the energy profile of the formation of alkaline-earth metal amidoboranes strongly depends on the nature of the metal M (M=Be-Ba). When moving from Be to Ba, reaction exothermicity increases, and the activation barriers for elimination processes both the first and the second hydrogen molecule are greatly reduced. This study was supported by the Russian Science Foundation (grant № 14-13-00151). [1] Graetz J. // Chem. Soc. Rev., 2009, 38, 73-82. [2] Stephens F., Pons V., Baker R. T. // Dalton Trans., 2007, 25, 2613-2626. [3] Xiong Z. T. et al. // Nat. Mat., 2008, 7, 138. [4] Frisch M. J., Trucks G. W., Schlegel H. B., Scuseria G. E., Robb M. A., Cheeseman J. R., Montgomery J. A. Jr., Vreven T., Kudin K. N., Burant J. C. et al. Gaussian03, revision B.05. Gaussian, Inc.: Wallingford CT, 2004. [5] Becke, A. D. // J. Chem. Phys., 1993, 98, 1372-1377. [6] Lee C., Yang W., Parr R. G. // Phys. Rev. B, 1988, 37, 785-789. [7] Weigend F., Ahlrichs R. // Phys. Chem. Chem. Phys., 2005, 7, 3297-3305.

1981

First principles calculations of the electronic properties of oxygen vacancy of ZnO

A.B. Usseinov1, E.A. Kotomin2, Yu.F. Zhukovskii2, A.T. Akilbekov1, F.U. Abuova1

1L.N. Gumilyov Eurasian National University, Astana, Kazakhstan 2Institute of Solid State Physics, University of Latvia, Riga, Latvia

Abstract: Knowledge of the atomic and electronic structure of defective ZnO is of great importance for improving performance of electrodes in optoelectronic devices based on transparent conducting oxides, e.g. LED displays, solar batteries , etc [1]. Here, particular interest is theoretical understanding the role of native point defects such as an oxygen vacancy. It is known that the common approximations to DFT, viz., the local density approximation (LDA) and the generalized gradient approximation (GGA), systematically underestimate band gaps of semiconductors and insulators. Since the band gap is the relevant energy scale in the study of defects, this so-called “band-gap problem” of LDA and GGA severely affects the predictive power of these approximations when applied to defect levels [2]. We report results of the ab initio modeling of the oxygen vacancy in the ZnO structure based on hybrid DFT method (PBE0 exchange-correlation functional) as incorporated into the CRYSTAL-2009 computer code [3] using the supercell model and linear combination of atomic orbitals (LCAO) basis set. This approach allows us to obtain very accurate calculations of the optical gap and defect level positions therein. We carried out a theoretical analysis of the (+2/0) charge transition level of the oxygen vacancy in ZnO. We here showed that apparently conflicting theoretical results are in a much better agreement with each other when the charge transition levels are aligned with respect to the average electrostatic potential rather than to the respective valence-band maximum. We showed that the former alignment is equivalent to the choice of a common external potential such as the vacuum level, provided the electron densities are sufficiently accurately described. We have rationalized our finding by considering fundamental differences between the ways approximate density functionals describe localized and delocalized states. For localized states, the “band-gap problem” can generally be overcome through the consideration of total-energy differences. On the other hand, such a solution is not applicable to delocalized states, for which the “band-gap problem” remains an intrinsic shortcoming. [1] A. M. Stoneham, Theory of Defects in Solids: Electronic Structure of Defects in Insulators and Semiconductors (Oxford University Press, New York, 1975). [2] Janotti A and Van de Walle C G 2007 Phys. Rev. B 76 165202 [3] Dovesi R, Saunders V R, Roetti R, Orlando R, Zicovich-Wilson C M, Pascale F, Civalleri B, Doll K, Harrison N M, Bush I J, D'Arco P and Llunell M 2009 CRYSTAL09 User's Manual University of Torino, Torino.

1982

Electronic structure lumenescence comlexes of rare-earth elements (Sc, Y, La ) from the results of studies density functional theory

V.V. Korochentsev, V.I. Vovna, I.S. Osmushko, A.G. Mirochnik

Far Eastern Federal University, Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia

Abstract: Methods quantum chemistry are applied to study tris-dibenzoylmethanates of rare-earth elements (Sc, Y, and La). New information on the electronic structure of the complexes is obtained: the geometric and electronic structures of the compounds are calculated, the nature of the chemical bond of these compounds is established, the bands in X-ray photoelectron spectra of the valence and sub-valence regions are identified. The fundamental problem of chemistry and photochemistry of lanthanide complexes of the island and polymer structures is to reveal the so far unknown mechanism of the effect of the nature of the chemical bond on their fluorescent and photochemical properties. In this work, by means of the XPS and DFT methods the electronic structure of tris-dibenzoylmethanates M(Dbm)3 of three REEs (Sc, Y, La) not containing 4f-electrons, which simplifies the interpretation of the valence region spectra, is investigated. Having a strong -conjugated system, a dibenzoylmethane molecule facilitates effective transfer of the electron excitation energy to the resonance levels of the rare-earth ion The calculated energies, the sequence of upper MOs, and the electron density localization on Sc, Y, and La dibenzoylmethanate atoms are summarized in Table In all complexes, two upper 3(a2), 3 MOs are mainly localized on the chelate rings and have 20—21 %contributions of the phenyl groups, according to the results of the calculation in the Mulliken approximation. In the three complexes, the energies of e splitting3(a2) HOMOs between coincide the а2 andwith е an accuracy 3 orbitals is highest in Y(Dbm)3 (0.16 eV). An increase in the Sc(Dbm)3  Y(Dbm)3 splitting is caused with a decrease in the metal contribution to 3 orbitals interaction due to a change in the geometry from D3 to D3h; in La(Dbm)3 an increase in the М—О distance from 2.26 Å to 2.,43 Å decreases the a2 – е splitting to 0.9 eV. Below n–(a2) МО there are nine orbitals mainly localized on the Ph rings. The coincidence of the symmetry and the similarity of energies lead to a mixing of n–(e) orbitals with the phenyl -orbitals in Y and La dibenzoylmethanates (Table 1, Fig.1). For two n+ МОs having the largest contributions of metal AOs among the ligand levels, the non-monotonic a – е splitting, similar to 3 levels. n+(а1) when the complexing agents are substituted is imposed on the above mentioned factor of changes in the series of the interligand interaction. The contributions of vacant nd and (n + 1)s AOs in n+(а1) are maximum for the Y and La complexes, and the stabilization of n+(e) by nd and (n + 1)p metal orbitals is highest for Sc. The project was carried out as part of the State assignment №2014/36 of the Ministry of Education and Science of the Russian Federation (on № 1137 FEFU).

1983

X-ray spectroscopy and quantum-chemical calculations to understand the chemical bonding in modified carbon nanomaterials

Yu. V. Fedoseeva1,2, L.G. Bulusheva1,2, A.V. Okotrub1,2, M. Kosinova1, E. Flahaut3,4, J. Zhou5, H. Song5

1Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk, 630090, Russia 2Novosibirsk State University, Novosibirsk, 630090, Russia 3Centre Interuniversitaire de Recherche et d’Ingenierie des Materiaux, Universite Paul-Sabatier, France 4CNRS, Institut Carnot Cirimat, F-31062 Toulouse, France 5University of Chemical Technology, Beijing 100029, China

Abstract: Chemically modified carbon nanomaterials attract attention due to their numerous spectacular properties, which are strongly dependent on the nature of functional groups and their bonding with carbon atoms. X-ray emission (XES) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopies are efficient experimental methods to study the electronic structure of nanomaterials. Analysis of XES and NEXAFS spectral features allows getting information about the chemical bonding, partial electron density of occupied and unoccupied orbitals, local surrounding of atoms, and forecasting physical and chemical properties. Interpretation of the X-ray spectra is actual problem for experimentalists and materials scientists. Modeling of the XES and XANES spectra using quantum chemical calculations provides detail information about peculiarity of the chemical bonding in studied substance. Here we demonstrate our latest developments in the study of electronic structure and modeling of XES and NEXAFS spectra of carbon-based nanomaterials. Objects of our study are fluorinated carbon nanotubes, detonation nanodiamonds with oxygenated surface, boron-and nitrogen containing carbon films, and graphene nanoparticles modified by metal sulfides. Hybrid method B3LYP with 6-31G* basis set was used to perform the quantum chemical calculations of the cluster models of modified carbon nanomaterials. We apply different approaches for modeling XES and NEXAFS boron, carbon, nitrogen and fluorine K-spectra. It was demonstrated that theoretical XES spectra constructed on the ground state calculation of cluster models show good agreement with experimental profiles. It was shown that electron hole in core level, which arises during measurements of X-ray spectra, should be taken into account in order to describe NEXAFS spectra. NEXAFS boron, carbon, nitrogen K-spectra are quite good described within the framework of the Z+1 approximation. Using IGLO (individual gauge for localized orbitals) basis set yields good results for modeling of NEXAFS FK-спектра. With help of quantum chemical modeling of X-ray spectra, we demonstrate peculiarities of the interaction of carbon nanomaterials with heteroatoms and metal sulfide. The work was supported by the Russian foundation for Basic Research (grant No. 14-03-91156), and the bilateral Program “Russian-German Laboratory at BESSY”.

1989

The Effect of Terminal Groups on Electronic Properties of [RGaNH]3n (R=H, CH3) nanorods

Pomogaeva A. V., Timoshkin A. Y.

Inorganic Chemistry Group, Institute of Chemistry, St. Petersburg State University, University Pr. 26, Old Peterhof, 198504, Russia

Abstract: GaN based materials are among the most popular for nanoengineering due to their high temperature and chemical stability. GaN based semiconducting nanorods serve as a channel for charge carriers with polarization-dependent conductivity with variety of applications in high-efficiency light emitting diodes, transistors, UV sensors, piezotronic devices and others. It is well known that end-effects can introduce significant changes in electronic properties of nanoscaled systems. The present study is devoted to comparison of structural and electronic properties of [RGaNH]3n (R=CH3,H) nanorods with two different types of termination. So-called “closed” oligomers are capped by additional metal-radical and imido groups. The other type is so-called “open” oligomer where the dangling bonds on the ends are simply saturated by hydrogens or functional groups. DFT B3LYP/SVP level of theory was utilized in this research to obtain optimized molecular structures and electronic spectra of [RGaNH]3n with n up to 38, that is about 10 nm in length. It was found that “closed” type of termination results in almost periodic structure of the oligomer where terminal effects are localized at the very edges of the rod. Band structure of the polymer was extracted from computations of “closed” rod with n=38. The “open” type of termination leads to a systematic change in structural parameters destroying a periodic pattern and increasing the number of end localized sates. The value of the dipole moment of “open” rods is much larger than the one of “closed” rods and it is faster increasing with the length. In the both cases HOMO-LUMO gaps are smaller than the band gap of the polymer and determined by localized states in the band gap. HOMO and LUMO states are heavily localized at the different ends of the rod that can cause a charge transfer upon excitation. For “closed” rods the value of the energy gap is almost stabilized ( 6.5 eV) for n=10, while for “open” rods it is not yet fully stabilized (2.1 eV) even for n=38. In our research we demonstrate that the way of termination of the nanorods along with adjusting the length of the rod could provide an effective control over the electronic and optical properties of the compounds in a wide energy range. This work was supported by SPbSU grants 12.38.255.2014 and 12.50.1563.2013. Research was carried out using computational resources provided by Resource Center "Computer Center of SPbU".

1992

The structure of atmospheric gases (N2, CO, Ar) polymolecular clusters

A.A. Milov, R.M. Minyaev, V.I. Minkin

Institute of Physical and Organic Chemistry at Southern federal University, 344090, Stachks ave., 194/2, Rostov-on-Don, Russia; Southern Scientific Center of Russian Academy of Sciences, 344006, st. Chehova, 41, Rostov-on-Don, Russia

Abstract: As ab initio method MP2(full)/6-311++G** studies have shown the most energetically stable complexes of 11 and 13 molecular complexes of atmospheric gases are icosahedral clusters of nitrogen molecules. At the same time, argon atoms complexes have the least stable. The 11 and 13 molecular icosahedral clusters continue the trend observed for the smaller molecular clusters where the growth of the number of molecules in the system increases the cooperative effect [1-2]. Calculations have shown that the most stable 11 and 13 molecular structures in gas phase are formed by a central nitrogen molecule. If the cluster are formed by many components that complete mixing is not observed, and the subsystem formed from identical molecules, but where the center is nitrogen molecule. Calculations show that there is a significant transfer of electron density from the central molecule to the cluster boundary. Analysis of molecular clusters by the atom in molecule Bader theory method shows the presence of bond paths between the central molecule of cluster with other atoms and molecules of the system, and the characteristics of bond points indicate the presence of a weak interaction between them. The Natural Bond Orbital (NBO) analysis gives similar results. Calculations showed no correlation between the stability of the cluster and its molecular volume. [1] Gribanova T.N., Milov A.A., Gapurenko O.A., Minyaev R.M., Minkin V.I., Starikov A.G., Gurashvili V.A. Cooperative effects in polymolecular nitrogen clusters. Russian Chemical Bulletin. 2008. Vol. 57. N 10. Pp. 2037-2044. [2] Gribanova T.N., Milov A.A., Gapurenko O.A., Minyaev R.M., Minkin V.I., Starikov A.G., Gurashvili V.A. Structure and stability of the mixed polymolecular complexes of nitrogen and carbon nonooxide: a quantum chemical study. Russian Journal of General Chemistry. 2011. Vol. 81. N 5. Pp. 807-818. Work carried out in the framework of the Project of the Ministry of Education of Russia in scientific research (project N 4.71.2014/K).

1997

The relaxational model of superconducting temperature forming and the example of its possible application

Yuryeva E.I.

The Ural State College named after Ivan I. Polzunov, Lenin av. 28, 620014, Ekaterinburg, Russia, Ural State Agrarian University, Karl Liebknecht st., 42, 620075, Ekaterinburg, Russia

Abstract: Now it is still actually to establish the microscopic mechanisms of high-temperature superconductivity (HTSC) in a series of layered copper oxides. The character of atomic bonding in superconductors with low and high TC differs essentially [1] but we think that fundamental tenets of the BCS theory [2] are also valid for high-temperature (high-TC) superconductors (SC). In this work we reviewed the moving of free and non interacting electron in condensed matter with the not zero temperature within molecular-kinetic theory of rarefied gas and in according with introduced expansion of Drude theory. The introduced in this work expansion of Drude theory consists of details of mechanism for inelastic interaction of free conductor electron with ionic core. Earlier in article [3] the author of this work introduced the assumption that the potential energy of electron with ionic core may be calculated according the expression: Epot=Pbin(Ne)-Pbin(Ne-1),where is reduced binding energy on one electron from system or valence electrons and on one proton from atomic nuclear system, which formed the investigation system. If the kinetic energy of free electron equals reduced binding energy we can write as: (3/2)kBT=Pbin(Ne)-Pbin(Ne-1). Then minimal value of temperature which can cause realization of non elastic impact of electron with ionic core we can calculate using the expression: Tmin=(2/(3*kB))[(Ne)-Pbin(Ne-1)]. When the value of ambient temperature become smaller then value Tmin in this case the impact of electron with ionic core will stop out. And the electron motion under the potential difference will be realize without dissipation of mechanic energy. And as result in this case the resistance of electron currency will disappear. The last expression will mean the transition of material to the state of superconductivity, i.e. Tmin = Tс, where Tс will be superconducting transition temperature. In framework of previously proposed model [3] and according with introduced in this work expansion of Drude theory the evaluation of possible superconducting temperature for yttrium-barium ceramic was carried out. [1]. M.M. Doria, A.R. de Romaquera, S. Salem-Sugui, Jr., Vanishing of the upper critical field in Bi2Sr2CaCu2O8+δ from Landau-Ott scaling, Phys. Rev. B., (76) 2007, 052504-1 - 052504-3. [2]. J. Bardeen, L.N. Cooper, J.R. Schrieffer, Theory of Superconductivity, Phys. Rev., (105) 1957, 1175 – 1204. [3]. E.I. Yuryeva. Stability of fragments of condensed matter. Saarbrucken, Deutschland: LAP Lambert Academic Publishing, 2012, 1-557. [in Russian].

2002

Chemical modification of Pt particles surface in nanocatalysis: a DFT study on the Pt40 and Pt41 clusters

Oleg B. Gadzhiev*, Stanislav K. Ignatov*, Artem E. Masunov**, Alexei G. Razuvaev*

N.I. Lobachevsky State University of Nizhny Novgorod, Russia **University of Central Florida, USA

Abstract: Methodologies for preparation of facet-controlled nanoparticles (NPs) are developed intensively since the shape-selected nanoparicles exhibit often selective catalytic properties [1]. Moreover, due to shape selection, the NPs can be building blocks of advanced nanomaterials with high surface area, which is an important feature of the catalyst. The most methodologies of these structures preparation are based on surfactant specific stabilization of the facet. That is, the manipulation of surface energy of a given facet using surface-binding molecules has been the major synthetic strategy. However, the data on specific adsorption energy are very scarce. In the present, we addressed to these properties. In order to elucidate catalytic properties of Pt NPs capped by DDT (1-dodecanethiol) in the crotonaldehyde hydrogenation [1], quantum chemical study of (finite, free) three-layer clusters Pt41{100} and Pt40{111} as models for different facets of Pt NPs corresponding to crystallographic planes was conducted. BuSH was used as a model for DDT. The study was performed with BLYP density functional in conjunction with CRENBS effective core potential (ECP) and orbital basis set for platinum, LANL2DZdp ECP and orbital basis set for sulfur, and 6-31G(d,p) all-electron basis set for carbon, oxygen, and hydrogen atoms. As was calculated at the BLYP/Pt(CRENBS)+S(LANL2DZdp)+C,H,O(6-31G(d,p)) theory level, 1) the adsorption energy of BuSH shows moderate dependence on the adsorption mode onto the studied clusters, i.e., for Pt40{111} and Pt41{100} the calculated values are -144.9 kJ/mol and -172.6 kJ/mol, respectively; 2) energy of physical adsorption for BuSH in the single molecular approximation is remarkably lower than the corresponding dissociative adsorption (Er= -135.4 kJ/mol); 3) CO is an ambidentate ligand in the approach to the Pt cluster; 4) coordination through carbon atom onto Pt cluster surface is thermodynamically highly favorable with respect to coordination through the oxygen atom of CO; 5) two-and four-fold coordination modes were determined for CO adsorption through carbon atom onto Pt41{100} model surface (Eads= -172.6 kJ/mol). In the later case, three bond lengths are about of 2.22 Å while the fourth one is about 2.41 Å; 6) the IR vibrational shifts for the stretch mode of CO (sharp mode in the simulated IR-spectra) due to adsorption are -200 cm-1 and -330 cm-1, respectively to the adsorption mode; 7) CO can compete with BuSH for the adsorption site even in the single molecular approximation; 8) for the three-fold CO coordination on Pt40 (hollow site) the adsorption energy is - 171.3 kJ/mol that negligibly deviates from the favorable adsorption mode onto Pt41; however, the vibrational shift is -284 cm-1. In the present study, two very common poisons for Pt-based catalysts were characterized by the adsorption modeling with Pt40 and Pt41 clusters. [1] L. Altmann, S. Kunz, M. Bäumer, J. Phys. Chem. C 2014, 118, 8925-8932

2015

Structural, electronic, thermodynamic and spectral properties of magnesium clusters Mgn (n=2-31). A DFT study

Belyaev S.N., Panteleev S.V., Ignatov S.K.

Lobachevsky State University of Nizhny Novgorod

Abstract: The properties of small magnesium clusters Mgn (n=2–31) are very important for coordination and organometallic chemistry because they are a convenient model for the Grignard reactant formation on the activated magnesium surface. In the present study, the structural, electronic, spectroscopic, and thermodynamic properties (including the energies, enthalpies, and the Gibbs free energies of formation and atomization) of the small clusters Mgn (n=2-31) were studied using the DFT method at two levels of theory (B3PW91/6-31G(d) and B3PW91/6-311+G(2d)). The optimization of the cluster structures was performed in a systematic manner for both singlet and triplet spin states, and the IR spectra of the optimized structures were calculated. It was found that the difference between the structures optimized at two levels theory are not very pronounced as well as the difference between the singlet and triplet structures (typical changes in interatomic distances are about 1-2%.). The energies of triplet states are usually higher by 2-5 kcal/mol. The HOMO energies and the band gaps of the clusters demonstrate slow convergence to the metal limit but the largest clusters remain to be semiconductors. The atomization energies and the Gibbs free energies of atomization demonstrate the clear linear dependence on the n^(-1/3). As a whole, the calculated thermodynamic functions (energy, enthalpy, entropy, and the Gibbs free energy) demonstrate the slow convergence to the limiting values, and this convergence is better in the case of the higher theory level. The IR spectra of the clusters shows that the absorption bands of the clusters are located in the region of 40-270 cm-1. In the case of small clusters there are several distinct bands which form the broad structured band in the case of large clusters. Among the features of this broad band, the distinct intense maxima at 200-250 cm-1 and 120-150 cm-1 take place which allows registering and identification of the different kinds of clustersformed or isolated in the inert matrices. The study was supported by the Russian Foundation for Basic Research (Project No. 14-03-00585)

2018

Еlementary reactions of the cluster mechanism of SOCl2 hydrolysis in the gas phase

Maria A. Zasovskaya StanislavK. Ignatov

Ukhta State Technical University N.I. Lobachevsky State University of Nizhny Novgorod

Abstract: Quantum chemistry methods (DFT, MP2, G4, and CCSD(T)) were used to calculate the energies, thermodynamic and kinetic parameters of elementary reactions of thionyl chloride (SOCl2) hydrolysis in the gas phase involving bi- and termolecular clusters. Optimization of molecular geometry and search for all the intermediates and transition states were performedat the B3LYP/6-311++G(2d,2p) and MP2/6-311++G(3df,3pd) levels. For some key stationary points, the CCSD(T)/cc-pVDZ and CCSD(T)/aug-cc-pVTZ full optimizations were carried out. For both bi- and termolecular reactions, overall minimum energy reaction paths were constructed to connect all the discovered stationary points. The results show that water dimers involvement leads to a significant decrease in activation energy but not in the Gibbs free energy of activation. It was discovered that the termolecular hydrolysis of first S-Cl bond consists of two steps and runs through the intermediate in which the coordinated SOCl2 molecule has a flat structure. The quantum chemistry methods (B3LYP/6-311++G(2d,2p) and MP2/6-311++G(3df,3pd)) were used to study the elementary steps of thionyl chloride hydrolysis reaction in gas phase with one or two water molecules. The thermodynamic parameters of elementary hydrolysis steps were studied, and continuous reaction paths connecting all stationary points on the potential energy surface were constructed. The obtained data confirms the conclusions drawn earlier that the termolecular hydrolysis mechanism has lower activation barriers both in terms of energy and Gibbs free energy. In this case the activation energy is by 41 kJ mol-1lower than the activation energy of the bimolecular reaction based on the B3LYP calculation data (62 kJ mol-1according to MP2 calculation data). The rate-determining step of the termolecular hydrolysis is the second S-Cl bond hydrolysis step. Its activation energy relatively to SOCl2+2H2O is 77.5 (B3LYP) or 56.3 (MP2) kJ mol-1. In a similar way, Gibbs activation energy is 160.4 (B3LYP) or 140.4 (MP2) kJ mol-1

2024

Ketones reactions with phenylacetylene in the KOH/DMSO superbasic system

V.B. Kobychev,* N.M. Vitkovskaya,* V.B. Orel,* and B.A. Trofimov**

* Irkutsk State University, 1 Karl Marx Str., 664003 Irkutsk, Russia; ** A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1 Favorsky Str., 664033 Irkutsk, Russia

Ketones are known to interact with acetylenes in the presence of basic catalysts yielding propargyl alcohols (Favorsky reaction). Additionally to this common knowledge, ketones were recently found to be capable of vinylating by arylacetylenes in the superbasic catalytic system KОН/DMSO to give the beta-gamma-unsaturated ketones [1]. At contrast to typical nucleophilic trans-addition to arylacetylenes yielding adducts of Z-configuration, the ketones nucleophilic addition to phenylacetylene exhibits E stereoselectivity. The mechanism of acetone ethynylation and vinylation with HCCPh in the presence of KОН/DMSO is investigated within the ab initio MP2/6-311++G**//B3LYP/6-31+G* approach. The superbasic reaction center was represented by a KOH·5DMSO complex of the non-dissociated alkali hydroxide molecule with five solvent molecules of the nearest environment; the rest solvent effect was treated via a PCM continuum approach. The reaction profiles obtained give rise to specifying of three temperature area. At a low temperature the reaction system follows the ethynylation pathway with small activation energy 5.9 kcal/mol to form tertiary acetylenic alkoholate. Being heated up to 40-60°C, reagents could be able to overcome the 16.3 kcal/mol activation barrier for a thermodynamically preferable vinylation branch. A specific trans- deformation of the acetylenic substrate in the TS causes a predominant formation of (4Z)-5- phenylpent-4-en-2-one. Nevertheless, the intermediate carbanion could undergo the E–Z isomerization with a relatively low activation energy 9.8 kcal/mol comparable to that of the carbanion protonation with the inner-shell water molecule. Thus, one should expect a mixture of E- and Z-isomers formation. Both E- and Z-isomers of 5-phenylpent-4-en-2-one formed show an increased C-H acidity in the KOH/DMSO surrounding, and the final ketone presents in the reaction mixture in its enolate form. The activation energy of enolate ion E-Z transformation is 30.8 kcal/mol, and this kind of isomerization needs heating up to 100°C. Indeed, a 100% E-stereoselectivity occurs for enolisable ketones under heating for an hour. Activation energies of the vinylation stage obtained within a simplified model with a single solvent molecule explicitly included have demonstrated a good agreement with the results of the extended model. The activation energies of substituted ketones (pinacolone, acetophenone, 2- methylcyclohexanone) vinylation found in the framework of this model reproduce well the differences in their reactivity. This work was supported by a project part of Government Assignment for Scientific Research from the Ministry of Education and Science, Russia (No. 2014/51, project code 206), and the RFBR grant No. 15-03-03880a. [1] Trofimov, B.A.; Schmidt, E.Yu.; Zorina, N.V.; Ivanova, E.V.; Ushakov, I.A. J. Org. Chem., 2012, 77, 6880.

2034

A Nexus between Electronic Structure and Spectral Properties of the Biologically Active Compound – Echinochrome A: a Quantum Chemical Study

Valerii I. Kharchenko (a, b), Alexander I. Cherednichenko (a, b), Leonid N. Alexeiko (a)

(a) Far Eastern Federal University, Vladivostok, Russia, (b) Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia

Abstract: Spinochromes possess numerous intra- and intermolecular hydrogen bonds as well as high-mobile protons [1]. Compounds of this class have shown high efficiency as biogenic antioxidants and high- conductive organic systems. One of such compounds, echinochrome A (Ech A), 2,3,5,6,8-penta- hydroxy-7-ethyl-1,4-naphthoquinone, being a naphthoquinoid pigment from the sea urchins, is characterized by antioxidant, antimicrobial, anti-inflammatory, as well as chelating abilities. Moreover, Ech A is a main active substance in the ophthalmic and cardiac drug Histochrome®. The therapeutic potential of Ech A for reducing cardiotoxic agent-induced damage has been confirmed, but its underlying cardioprotective mechanisms are not well clarified [2]. The purpose of this work was to apply methods of quantum chemistry to study the electronic structure of Ech A in the ground and excited states in order to find a way of understanding such protective mechanisms of this compound. Quantum chemical calculations of the Ech A electronic structure and spectral characteristics were carried out by the ab initio RHF/CIS and time-dependent density functional theory DFT/TDDFT/PBE0 methods with the basis sets 6-311++G** in a vacuum approximation within the cluster approach using the GAMESS-US program package [3]. The quantum-chemical modeling has been shown to give a rather correct description of the structure and unique spectral properties of Ech A. According to the calculated and experimental IR and Raman spectra, a substantial delocalization of π-conjugated systems of the quinoid and benzenoid rings, when intra- and intermolecular hydrogen bonds of OH groups are formed, might cause a stabilization of the quinoid ring. The calculated UV absorption spectra of Ech A are featured by bands between 380 and 500 nm. According to the calculations, the bands are mainly associated with HOMO(π) and HOMO-1(π) → LUMO(π*) electronic transitions. The present study has shown an importance of further carrying out more sophisticated quantum chemical modeling of some reactions involving Ech A to clarify mechanisms of its high bioactivity. This work was supported by the Russian Ministry of Education and Science within the state contract No. 2014/36 with Far Eastern Federal University (project No. 1137). [1] D. V. Berdyshev, et al. Russ. Chem. Bull. 3 (2007) 413. [2] S.H. Jeong, et al. Mar. Drugs 12, 2922 (2014). [3] M.W. Schmidt, et al. J. Comp. Chem. 14, 1347 (1993).

2035

The effects of noncovalents interactions in the co-crystal of Piroxicam and Meloxicam with carboxylic acids like co-formers

Christian Tantardini, Sergey G. Arkhipov, Elena V. Boldyreva

Novosibirsk State University This research was supported by Russian Ministry of Education and Science (project 1828).

Abstract: Oxicams are non-steroidal anti-inflammatory analgesics, classified as ECB II (FDA regulations). Those belonging to this class show a high bioavailability and low solubility in aqueous environments. As a result, ECB II compounds exhibit difficult absorption properties in biological organisms, but once absorbed, even at low doses, invoke a very strong response with, making them an important pharmaceutical target. In their current form their high bioavailability associated with poor solubility make them unsuitable as rapid relief painkillers. The oral administration is preferred respect other form of administration by the patients and thus many active pharmaceutical ingredients (API) are synthesized in solid form with other additivies in the form of tablets capsules granules pills. All drugs for the oral administration should show good solubility, thus for all of them with low water solubility it's important to increase this property and there are many different techniques that it is possible to use. These techniques are based on the addition of additives but it's necessary that the additivies are biocompatibility, thus under this aspect the carboxilic acids find a good employment to form co-crystal, salts, solvates. The oxicams are included in this category of API that can make co-crystals, salts, solvates with appropriate co-formers and specially when we use carboxylic acids, they show higher solubility compared to the crystals of oxicams alone or with other co-formers. The aim of our work is to evaluate how Non Covalent Interactions (NCI) vary in co-crystals of piroxicam and meloxicam by varying the degree of saturation of a co-former of dicarboxylic acid and varying its structural isomers where present. The experimental part of this study shows the techniques of crystallization to obtain new co-crystals of piroxicam and meloxicam with dicarboxilic acids with single, double and triple carbon- carbon bonds. The theoretical part of this study begin with the application of density functional theory (DFT) with different level of theory to obtain the theoretical density subsequently there will be a complete Bader's Analysis of all the co-crystals, in order to understand, how the contributions of different atoms influence intramolecular and intermolecular bonds. The Bader's analysis will begin searching the critical points of charge density and after the study of Laplacian of charge density to see the form of atomic basins and non nuclear attractors. In the critical points that they are considered interesting to describe the charge distribution as bond critical points and maximum and/or minimum of Laplacian it was calculated the contributions of Source Function (SF). These contributions allow to evaluated the influence of H-bond at the charge distribution in the co-crystals with different abilities to form intramolecular and intermolecular H-bonds, and for different structural isomers of the same molecules.

2042

Multi-state vibronic interactions in cis-1,2-dichloroethene radical cation

D. Yu. Soshnikov*, A. B. Trofimov*, D.M.P. Holland**

*Laboratory of Quantum Chemistry, Irkutsk State University, 664003 Irkutsk, Russia **Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD, UK

Abstract: The photoelectron spectrum of cis-1,2-dichloroethene exhibits three complex bands between 11.3 and 12.9 eV. Despite the high experimental resolution, only the lowest band (11.3-11.9 eV) shows vibrational structure below 11.7 eV. Above this energy the spectrum is rather diffuse and structureless. The most striking feature of the spectrum is the splitting of the second band (11.9-12.3 eV) into two 2 strong components, which cannot be explained in terms of the non-interacting cationic states, 1 B2, 2 2 1 A1, and 1 A1, contributing to the energy region under consideration. In the first stage of our study, the influence of the other cationic states was excluded by computing the vertical ionization spectra using OVGF and ADC(3) propagator methods. A closer examination of the 2 2 2 potential energy surfaces of 1 B2, 1 A1, and 1 A1 states revealed a possibility of vibronic coupling among these states. In our preliminary study the splitting of the second band was reproduced when the 2 2 interaction of 1 B2 and 1 A1 states was taken into account. The more rigorous modeling was performed using diabatic vibronic Hamiltonians [1]. The parameterization of the model was accomplished using OVGF/cc-pVTZ and MP2/cc-pVTZ calculations for the ionization energies and ground state parameters, respectively. The model takes into 2 2 2 2 account interaction of 1 B2 and 1 A1 states via single b2 mode and interaction of 1 A1 and 1 A2 states via two a2 modes. According to the present results, these interactions give rise to the conical intersections of the corresponding potential energy surfaces near 11.87 and 12.39 eV, respectively. The 2 2 photoelectron 1 A1 and 1 A2 bands are therefore lying entirely in the domain of the nonadiabatic nuclear dynamics, which can be seen from the highly complex structure of the computed vibronic 2 spectrum. The part of 1 B2 band below the conical intersection can still be interpreted within the adiabatic approximation in terms of the excitations of the totally symmetric a1 modes and in-plane b2 bending modes. The computed vibronic spectrum is in good qualitative agreement with measurements, confirming the adequate level of the present vibronic treatment. By contrast, the Franck-Condon calculations using model Hamiltonian without vibronic coupling terms are unable to reproduce the spectrum even qualitatively. This work was supported by grant No. 4.1504.2014/K from the Ministry of education and science of the Russian Federation. [1] H.Köppel, W. Domcke and L.S. Cederbaum, Adv. Chem. Phys.- 1984.- Vol. 57.- P 59.

2048

Mechanism of spin-state changing of Ni(II) diketonates under self-association. Quantum chemical modeling.

Starikov A.G., Starikova A.A., Minkin V.I.

Institute of Physical and Organic Chemistry at Southern Federal University

Abstract: Recently, it was proposed to use the configurational isomerism as an instrument for controlling magnetic properties of nickel complexes. Photoinduced cis-trans isomerisation of properly functionalized ligands is accompanied by the formation of a new bond with metal center, which change the coordination type and spin-state of the complex [1]. This idea follows from the research data of association/dissociation of bis-chelate nickel complexes. The isolated molecules of nickel diketonates have planar structure of coordination site and are characterised by the low-spin state of metal atom. In solution and solid state, such complexes form the trimeric associates, in which nickel atoms have pseudo-octahedral coordination site and the high-spin state owing to the additional coordination of oxygen atoms of adjacent molecules. With the aim to elucidate the mechanism of this phenomenon the DFT (B3LYP/6-31G(d,p)) calculations have been performed. As a research object we used bis-(dibenzoylmethanato)Ni(II), for which in crystalline state both monomeric and trimeric forms have been detected. According to the calculations, dissociation of the trimer can pass through two routes, differing by the geometry of the structures with intermediate spin states. The first pathway implies the formation of the associate, in which metal-metal contacts are elongated to 3.07 Angstrom, while the central complex has planar coordination site and is characterized by the low-spin state of metal atom. The further elongation of the distance between molecules results in the isomerisation of the external complexes and changing of their stereochemistry from pseudo-octahedral to square-planar. When moving the reaction system by the second route, the planarization of the chelate cycles of one of the external complexes occurs and its nickel atom is stabilized in the low-spin state. Thereafter as a result of dissociation of the dimer the weakly coupled associate, containing diamagnetic complexes, is formed. Calculated structures with the intermediate spin-state have similar total energies, which doesn’t allow to make a choice in favour of one of the routes. In order to elucidate the mechanism of dissociation of the trimer involved the search for MECP (minimal energy crossing point) has been carried out. The calculation led to a structure, in which one of the exterior complexes is removed at the considerable distance (Ni-Ni distance is equal to 4.04 Angstrom). This finding allows to conclude that the initial stage of the dissociation of the bis- (dibenzoylmethanato)Ni(II) trimer is the separation of the external molecule of the complex, accompanied by the transition of metal atom to the low-spin state. This research was performed in the framework of SFedU grant N 213.01-2014/005VG. [1] S. Venkataramani, U. Jana, M. Dommaschk, F. D. Sonnichsen, F.Tuczek, R. Herges, Science, 2011, 331, 445.

2056

A Theoretical Study Of Ethyne Hydroformylation On Platinum Complexes With Hydrophosphoryl Ligands

V.G. Savchenko, Yu.V. Babin

Far Eastern Federal University, 8 Suhanova St., Vladivostok, Russia Moscow State University Of Food Production, 11 Volokolamskoe Shosse, Moscow

Abstract: Higher stability of hydrophosphoryl complexes (HPC) against oxidation is their undoubtful advantage as ligands over tertiary phosphines traditionally used in catalysis. In 1986 van Lewen at al. demonstrated for the first time the catalytic potential of HPC ligands in the Pt catalized hydroformylation of olefins [1]. The hydroformilation of 1-heptene on the complex hydride [(Ph2 PO)2 H]Pt(PPh3 )H (1) occurred under mild conditions with a regioselectivity of more than 90%. Since 2001 that ligands have been used to a greater extent in homogenous catalysis. One interesting detail of the ligand coordination in (1) is the strong intramolecular hydrogen bond in the backbone that leads to the formation on bidentate ligand which makes the geometry of the catalytic center rigid. Theoretical studies revealed that the ease migration of the proton within PR2O-H…O-PR2 chain provides fine adjustment of the electron density in each reaction step [2]. We used model complex (1) with aryl groups replaced by hydrogen atoms for theoretical simulation of the mechanism of ethyne hydroformylation. The model catalytic cycle is basically corresponding to the Wilkinson’s mechanism for the hydroformylation and hydrogenation of olefins. The entire cycle began with ethyne coordination to produce n2-adduct complex, and the next step was ethynyl insertion into Pt-H bond. Hydroformylation then proceeded with CO insertion, H2 addition and elimination, while hydrogenation proceeded with just H2 addition and elimination steps. The molecular and transition state geometries were fully optimized on PBE/TZ2P level with the SBK-JC pseudopotentials used for the core electrons. The stationary point energies were obtained from calculations with inclusion of zero point vibrational energy correction. The correspondence between the transition states and initial compounds and reaction products was verified by constructing the IRC. We came to conclusion that ethyne addition was irreversible step while acrolein elimination was rate-determining step for the whole catalytic hydroformylation cycle. The energy barrier for the competitive reaction of hydrogenation was obviously higher than that for hydroformylation so the hydroformylation of ethyne is much more preferable process than hydrogenation, in contrast with the case of rhodium catalysts. [1] P. W. N. M. van Leeuwen, C. F. Roobeek, R. L. Wife and J. H. G. Frijns, J. Chem. Soc., Chem. Commun., 1986, 31 [2] Yu.A. Ustynyuk, Yu. V. Babin, and V. G. Savchenko, Doklady Physical Chemistry, 2010, Vol. 430, Part 2, pp. 25–28

2060

Electron-count rules for extended-chain bipyramidal and sandwich complexes of s- and d-metals

Tatyana N. Gribanova, Ruslan M. Minyaev and Vladimir I. Minkin

Institute of Physical and Organic Chemistry at Southern Federal University, 344090 Rostov-on-Don, Russian Federation

Abstract: Structures and stability of a series of extended-chain bipyramidal, sandwich and sandwich-bipyramidal mixed complexes formed by conjugated cyclic hydrocarbons (CH)n with s- (Li, Na, K, Be, Mg, Ca) and d- (Cr, Mn, Fe) metals have been studied using DFT B3LYP/6-311+G(df,p) calculations. For all considered stable bipyramidal, sandwich structures formed by only s-metals atoms the sum of valence electrons of metal atoms and pi-electrons of basal cycles must be equal to 6n (rule 1), where n - total number of the basal cycles. Stable structures of bipyramidal and polysandwich complexes (including their mixed derivatives) composed by only d-metal atoms must satisfy to the rule, according to which the sum of valence electrons of metal atoms and pi-electrons of basal cycles is 12m + 6 (rule 2), where m - total number of transition metals atoms. The electron-count rules (1) and (2) cannot be applied to the mixed type complexes containing both s- and d-metal centers. For such type systems including s- and d-metals and mixed derivatives the generalized electron-count rule (3) will be valid, according to which for a stable complex the sum of all valence electrons of metal atoms, apical groups and pi-electrons of basal cycles is equal to 6n + 6d + 12c, where n - total number of hydrocarbon cycles; d – total number of d-metal atoms (or separate sandwich moieties); с – total number of metal-carbonyl groups. The rule (1) is a particular case of the generalized rule (3) under conditions d = 0, c = 0 and the rule (2) is derived from (3) for d-metal sandwiches with c = 0, n = d + 1 and for bipyramidal structures with n = d + 1, m = d + c. The generalized electron-count rule (3) holds true also for the nonsymmetric systems including only one apical group. The rules (1) – (3) represent an extension of well-known principles of aromaticity of organic and metal coordination compounds to the particular structural type systems. The rule (1) is, in fact, a consequence of the principal condition for an aromatic (4–6)-membered system to form the closed 6pi-electron shell, whereas the rule (2) reflects requirements of the 18-electron rule for transition metal complexes with several d-metal centers. The aromatic character of the isostructural compounds formed by d-metals is substantially stronger than that for the s-metal derivatives. For the multi-decker d-metal compounds, lengthening the -M-ring- M-ring- chains is accompanied by increase in the aromatic stabilization, but does not practically affect the aromatic properties of the hydrocarbon cycles of the analogous s-metal compounds. This work was supported by the Ministry of Education and Science of the Russian Federation within the State Assignnment for Research (Project part, Project 4.71.2014/K).

2061

Pros and cons of accelerated modeling of Si(110) passivation by atomic layer deposition of Al2O3

Andrey A. Rybakov, Alexander V. Larin, Georgy M. Zhidomirov

Department of Chemistry, Moscow State University, Leninskie Gory, Moscow, GSP-2, Russia 119992; OOO Plasmonika, Ural Building, 100, Novaya str., Skolkovo, Moscow region, Russia 143025; c Boreskov Institute of Catalysis, SO RAN, Novosibirsk, 630090, Russia

Abstract: Typical structural defects are studied theoretically in the course of O sitions Al  on O atomic de the basic Si(110) surface. The defects are determined by analyses of the band gap states and projected densities of the s- and p-states after the deposition aimed to form a Si(110)/SiOX/AlOY/ -Al2O3 slab. The extent of Si(110) passivation after each deposition step is studied by scanning the band structure calculated using Density Functional Theory with periodic boundary conditions. Our modeling reproduces most features of the use of any organic ligand as Al precursor along O2 plasma assisted atomic layer deposition (PA ALD) when the organic ligands are completely oxidized so that their participation can be neglected in the deposition as already shown experimentally. The passivated oxide Al2O3/Si layer is relatively thin, but nevertheless exceeds 10 Å, so that any computational hints to accelerate the growing of the interface instead of the numerous steps of successive O/Al/O/Al/… depositions could be useful. It is why we have used the merging procedure with Al16O30 (joined via two opposite sides which differ by the locations and numbers of O atoms) or Al16O24 fragments which led to a passivation in most of the cases. More precisely, the final oxidation step after O/Al/O/Al/… depositions corresponds to the junction of a slab of -Al2O3 fragment deposited over Si(110), whose super cell (SC) parameters have been selected to lead to the minimum mismatch. Different examples of either non-satisfactory or accurate junction of the oxidized Si(110) slab and -Al2O3 fragment are discussed aiming to develop a route for understanding the dominant defect types at the interface. A list of formed typical defects at the Si(110)/SiOX/AlOY/ -Al2O3 boundary is presented and characterized by the projected density of states and respective band structure around the band gap. We distinguished two types of possible drawbacks produced by joining the Si support and the oxide fragment. First, at small number of Al atoms (NAl = 4) per SC deposited on the oxidized Si slab, the oxide can attach the essential part of Al atoms thus redistributing them in favor of the oxide. The second negative effect of the proposed junction is related to the transformation of the OAl2 and OAl3 groups of the Al2O3 oxide layer. The defective states of the OAl2 groups could be previewed regarding three- or four-coordinated O atoms in the Al2O3 bulk, but the reasons of such transformation of OAl3 groups are less understood and could be assigned tentatively to a geometry distortion. The majority of the slab cases prepared by the junction possess by reasonable gap width that shows on the possibility of such approach in the modeling.

2065

Structure of NiCu Nanoparticles as derived from Monte Carlo and Molecular Dynamics simulations

Dmitrii V. Glukhov, #Paola Quaino, Shokirbek A. Shermukhamedov and Renat R. Nazmutdinov

Kazan National Research Technological University, 420015 Kazan, Republic of Tatarstan, Russian Federation; #Universidad National del Litoral, Santa Fe, Argentina

Abstract: Recently the surface structure of NiCu alloys is in the focus of a number of theoretical studies, while detailed information on segregation phenomena in NiCu nanoparticles (NP) is still lacking. Only a few attempts were made, however, to describe the structure of such NPs with the help of Monte Carlo (MC) and molecular dynamics (MD) method. In this work we employed atomistic MC and MD simulations (NVT ensemble) to gain a deeper insight into the structure of NiCu NPs of different size and shape, as well as in a wide range of their composition. Atomic interactions are described by a set pair Morse potentials and in the framework of Embedded Atom Method. Our computational strategy presumes the MD with annealing technique to model small NPs containing several hundreds atoms. Larger NPs (till 8400 atoms) are simulated using a lattice version of the Monte Carlo method. According to the results of simulations the segregation takes place at any composition of NPs. If the Ni fraction prevails, the Cu atoms tend to assemble in the surface region. In contrast, when the Ni is solute, the Ni atoms prefer to segregate at the particle surface. Our findings agrees qualitatively with the experimental data collected in literature for NiCu alloys. The most interesting prediction is the Ni segregation which supports challenging experimental observations reported in Refs. [1, 2]. The structure of model NPs differs, therefore, from the “core-shall” and “Janus-like” type, because the metal atoms are noticeably spread along the radial direction. Most of the metal atoms segregated on the surface area of NPs were found to form an island-like structure, although a minor number of isolated solute atoms are observed as well. This conclusion is supported by angular distributions calculated for the both metal atoms which clearly points to anisotropy. Such a striking feature originates purely from a competition between the interaction energies (enthalpy) and entropic factors and depends on the NP size. The formation of island-like patterns might elucidate the origin of segregation of solute Ni atoms. The Ni-Ni interaction energy which is stronger as compared with Ni-Cu and Cu-Cu might favour, on the one hand, the appearance of island structure. On the other hand, entropy factor is responsible for the extrusion of Ni atoms from core region of NP to its surface. We discuss the effect of size, shape of the NPs and their roughness on the segregation. Finally, emphasis is put on the comparison of the most qualitatively interesting features we observed with available experimental data. [1] T. Sakurai, T. Hashizume, A. Jimbo, A. Sakai, S. Hyodo, Y. Kuck, H.W. Pickering. Phys. Rev. B, 34 (1986) 8379-8390. [2] T. Sakurai, T. Hashizume, A. Kobayashi, A. Sakai, S. Hyodo, Phys. Rev. Lett, 55 (1985) 514-517.

2067

Photochemistry of 1,4-dithiane and aziridine cation radicals

Ivan D. Sorokin Oleg I. Gromov Vladimir I. Pergushov Mikhail Ya. Melnikov

Chemistry Department, M.V. Lomonosov Moscow State University, Moscow, 119991, Russia Department of Kinetics and Catalysis, N.Semenov Institute of Chemical Physics RAS, Moscow, 119991, Russia

Abstract: Mechanisms of reactions of intermediates (radicals, cation and anion radicals e.t.c.) are of great interest as intermediates play central role in overall description of chemical processes. Cation radicals of small heterocycles and their photoinduced reactions attract attention of researchers yet for some decades. Mechanistic studies mostly rely on EPR and UV-vis spectral data. Though frequently experimental data allow ambiguous interpretation. Here we present study of 1,4-dithiane and aziridine cation radicals photochemistry by means of EPR, UV-vis spectroscopy and DFT, CASSCF, MRPT2 and MRCI calculations. It was found, that in contradiction with literature 1,4-dithiane cation radical undergoes photoisomerization from 1,4-bath conformation to 1,4-twist bath conformation, while in literature the target conformation is considered to be 1,4-chair conformation. Calculated EPR parameters of 1,4-twist bath conformation better suite parameters of the product of photoisomerization. On the other hand calculated geometry of intersection of the first excited state and ground state of 1,4-bath indicates, that the product of photoisomerization is indeed 1,4-twist bath conformation. As for aziridine cation radical in Freon matrices, it was found, that cyclic form spectrum in visible region can be attributed to charge transitions from Freon molecules, while inner spectrum lies mostly in UV region. This explains, why photochemical bond breaking in cyclic form of aziridine cation radical do not take place under photolysis with >650 nm light, corresponding to the first band in visible spectrum, while photolysis with light with shorter wavelength results in bond breaking. The research is partially supported by RFBR Grants 12-03-33104, 13-03-00099, 14-03-32014 Calculations were performed using resources of the Supercomputing Center of Lomonosov Moscow State University. [1] V. Sadovnichy, A. Tikhonravov, Vl. Voevodin, V. Opanasenko "Lomonosov": Supercomputing at Moscow State University. In Contemporary High Performance Computing: From Petascale toward Exascale (Chapman & Hall/CRC Computational Science), pp.283-307, Boca Raton, USA, CRC Press, 2013.

1952

Modeling complex mixtures of asphaltenes and heavy oils at mesoscopic level by numerical simulation of Dissipative Particle Dynamics (DPD)

Carolina Del Valle Silva

INTEVEP, S.A, a subsidiary of PDVSA for scientific research, and

Abstract: The study of complex mixtures is nowadays an increasing and a very important field of research, motivated by the fact that multiphase complex mixtures appear in a wide range of technological and industrial applications. The behavior of complex fluids such as colloids, emulsions, polymers and other multiphase fluids, as petroleum systems, is strongly influenced by the coupling between the microscopic interactions producing collective properties at mesoscopic level which determine its macroscopic hydrodynamics properties. Heavy and extra heavy oil, which currently represents a very significant percentage of the available energy reservoirs, have the highest level of complexity due to several factors, the presence of the asphaltenes, which converts these crudes in extremely viscous fluids, and its high amount of heavy metals and the existence of heteroatoms. These properties not only make difficult its recovery, but also its study both theoretical and experimental. At the theoretical level, despite the computational power, even today it is not viable to represent and to study these systems at the molecular level. On the other hand, the study of parameters such as the local variation of interfacial tension, arise at scales greater than the molecular lengths, like the mesoscopic scale.The foregoing is motivating the representation and research of these complex systems on the scale mesoscopic, in the particular case of this work, the research is focused on the representation and study of systems of asphaltene characteristic of heavy crudes, to interfaces that come into contact with different solvents. A representation for an asphaltene system and asphaltene mixtures, typical of heave crude oil in the Orinoco Belt Hugo Chavéz of Venezuela (FPO), is proposed based on experimental data from PDVSA- Intevep, and Acevedo and collaborators of the Universidad Central de Venezuela (UCV). These were modeled at the mesoscopic level by applying Dissipative Particle Dynamics (DPD), where DPD beads correspond to the main structures that constitutes the real asphaltene fraction, making a super grained of each fraction. The Flory–Huggins parameter and the experimental solubility parameter (SP) were used in order to obtain the bead-bead repulsion parameters (aij), using the methodology developed by Groot and Warren (1997) and Pepe Español (1995-1997). The validation of the mesoscopic models of asphaltene and asphaltene mixtures obtained, it was through the study of the behavior of these systems toward the interface, evaluating the evolution of the Interfacial Tension and the density profiles, according to the solvents used, and variations of asphaltene/solvent concentration.

1960

Interactions between water, free radicals, and magnesium species on cellular membrane to study preeclampsia syndrome

Miguel Fernandez, Reinaldo Marin, Fernando Ruette

Instituto Venezolano de Investigaciones Científicas (I.V.I.C), Apartado 21827, Caracas, Venezuela

Abstract: Preeclampsia is a clinical syndrome of pregnant women and so far unique to humans. It is the leading cause of both maternal and fetal mortality affecting between 5 to 10 percent of pregnancies worldwide [1]. In this syndrome, the oxidative stress conditions increase, which markedly alter the structure and function of plasma membranes [2]. Lipids from the plasma membrane under these conditions are peroxidized by the action of free radicals (OH•), affecting the membrane integrity and decreasing fluidity [3]. The standard treatment of preeclamptic pregnant women is intravenous MgSO4 supply that decreases lipid peroxidation levels in cell membrane [4]. However, the mechanism of action is still unknown at molecular level. In a series of theoretical investigations of oxidized models of lipid bilayers, it has been found: the higher the degree of oxidation of a bilayer, this presents an increased area for lipid, decreased thickness and decreased mobility of lipids emphasizing that oxidized lipids bend their polar tails towards the interface with water [5]; the peroxyl radicals in lipid has a higher affinity to the hydrophobic region of the bilayer and prefer to stay in the depths of this [6]; Mg2+ and Ca2+ have similar affinities to the lipid bilayer of phosphatidylserine, however induce structural differences in bilayers which contain everyone presenting different binding sites and modifying the water of hydration of the bilayer [7]. In this direction, we have been made calculations at DFT, semiempirical and molecular dynamics levels • of MgSO4 interactions and other magnesium species, with the radical OH and models of lipid bilayers. Results show that there is a considerable Mg2+ interaction with the OH• radical, and this interaction 2+ increases with the presence of sulfate anion. The MgSO4/Mg are absorbed into the surface of a lipid bilayer, establishing that the MgSO4, which remains as an ion pair, penetrate further into the 2+ hydrophilic area of the bilayer than the Mg . Finally, these results explain the effect of MgSO4 in reducing the effect of oxidative radicals OH•. [1] Gabbe, S. G. Obstetrics: Normal and Problem Pregnancies. 6th ed. Elsevier, Saunders; 2012. [2] Jauniaux, E. 2003. Am. J. Pathol. 162, 115-125. [3] Halliwell, B. 1989. Free Radicals in Biology and Medicine. Clarendon Press, Oxford, U.K. [4] Ariza, A.C. 2005. Clin. Biochem. 38, 128-133. [5] Jarerattanachat, V. Karttunen, M. Wong-Ekkabut, J. J. Phys. Chem. B 2013 117 (28), 8490-8501 [6] Garrec, J. Monari, A. Assfeld, X. M. Mir, L. Tarek, M. J. Phys. Chem. Let. 2014 5 (10), 1653-1658 [7] Martín-Molina, A., Rodríguez-Beas, C., Faraudo, J., 2012. Bio. J. 102, 2095–2103

1972

+ + A generalization of Hellmann-Feynman theorem. Applications to H2, H2 and H3 .

Roger Hernandez

IVIC

Abstract: Differential equations has been deduced generalizing Hellmann-Feynman theorem and allow to perform calculations for potential energy curves and surfaces of molecules making use of 4 hypothesis: Locality, overlap dependence, implicit finite basis and overlap transferability. This four hypothesis and the system of differential equations allow to compute H2, H2+ potential energy curves and H3+ potential energy curve along an equilateral triangle. Formulas have been found that generalize Mayer approximations which allow to compute three and four centers functionals in terms of two centers functionals. A differential geometric interpretation has been found that allows to deduce an expression for the overlaps making use of a covariant derivative defined on a fiber bundle. This investigation is motivated by previous work done in parametric methods where overlaps and functionals are fitted by q- exponential functions. Differential equations has been deduced generalizing Hellmann-Feynman theorem and allow to perform calculations for potential energy curves and surfaces of molecules making use of 4 hypothesis: Locality, overlap dependence, implicit finite basis and overlap transferability. This four hypothesis and the system of differential equations allow to compute H2, H2+ potential energy curves and H3+ potential energy curve along an equilateral triangle. Formulas have been found that generalize Mayer approximations which allow to compute three and four centers functionals in terms of two centers functionals. A differential geometric interpretation has been found that allows to deduce an expression for the overlaps making use of a covariant derivative defined on a fiber bundle. This investigation is motivated by previous work done in parametric methods where overlaps and functionals are fitted by q-exponential functions. Differential equations has been deduced generalizing Hellmann-Feynman theorem and allow to perform calculations for potential energy curves and surfaces of molecules making use of 4 hypothesis: Locality, overlap dependence, implicit finite basis and overlap transferability. This four hypothesis and the system of differential equations allow to compute H2, H2+ potential energy curves and H3+ potential energy curve along an equilateral triangle. Formulas have been found that generalize Mayer approximations which allow to compute three and four centers functionals in terms of two centers functionals. A differential geometric interpretation has been found that allows to deduce an expression for the overlaps making use of a covariant derivative defined on a fiber bundle. This investigation is motivated by previous work done in parametric methods where overlaps and functionals are fitted by q-exponential functions.

2009

t Three-step adition of phenylsilane to imido complex ( BuN=)2Mo(PMe3)2: hydrosilylation mechanism and stability of intermediates in solvents

Andrey I. Okhapkina, Stanislav K. Ignatova and Georgii I. Nikonovb aN.I. Lobachevsky State University of Nizhny Novgorod, 23 Gagarina Avenue, 603950 Nizhny Novgorod, Russia b Brock University, 500 Glenridge Avenue, St. Catharines, ON, L2S 3A1 (Canada)

Abstract: Silylamido molybdenum complexes demonstrate quite unusual structural and chemical properties and, from this point of view, are interesting objects both for theoretical research and for practical applications, e.g. as catalysts of many chemical reactions: hydrosilylation of carbonyl compounds, alcoholysis and aminolysis silanes. Initial key step in many these processes is the addition of silane to the coordination sphere of molybdenum to form agostic intermediates. Earlier [1], it was theoretically t shown that the addition of one molecule PhSiH3 to complex ( BuN=)2Mo(PMe3)2 is a single-step reaction which results in the β-agostic adduct with significant kinetic barrier (Ea = 20.4 kcal/mol) that contradicts the experimental data. For this reason, in the present work we studied the new pathway of the the hydrosilylation reaction t between the imido complex ( BuN=)2Mo(PMe3)2 and phenylsilane by density functional theory (B3PW91/6-31G(d,p), Hay-Wadt DZ ECP for Mo atom). The existence of transition states have been confirmed by the presence of single imaginary frequency and by the further intrinsic reaction coordinate (IRC) calculation performed by the Gonzalez-Schlegel method. Assessment of solvents effects on the reaction energies was carried out using the continuum polarization model (PCM) for two solvents of different polarity (hexane and toluene). It was found that the reaction can occur by three-step mechanism different from that one described previously [1]. It consists of three steps: oxidative addition of phenylsilane, ligand rearrangement and PMe3 elimination. Limiting step of this mechanism is a direct silane attack on molybdenum atom with the initial formation of non-agostic intermediate with activation energy of 20.6 kcal/mol and subsequent rearrangement of the ligand environment. Among of studied complexes, the most favorable structure is the one with the imido group in cis-position to hydride atom. The effect of toluene and hexane solvents changes the relative stability of isomers in accordance with the increase of solvent polarity. The IR spectra of two main intermediates (previous and new mechanism) are significantly different which makes it possible in principle to distinguish theses isomers experimentally. This work was supported by the Russian Foundation Basic Research (RFBR) (project 14-03-00585). [1] A.Y. Khalimon, N. A. McLeod, S.K. Ignatov, A.I. Okhapkin, L. G. Kuzmina, J.A.K. Howard, and G. I. Nikonov, Dalton Transactions. 43 (2014)8446-8453.

2010

Selective hydrogenation of unsaturated aldehydes on the chemically modified sub-nanoparticle Pt24. A quantum chemical study

Stanislav K. Ignatov, Oleg B. Gadzhiev, Andrey I. Okhapkin, Alexey G. Razuvaev

N.I. Lobachevsky State University of Nizhny Novgorod

Abstract:

Supported Pt-based catalysts are considered today as most important catalytic systems for the hydrogenation of unsaturated compounds including the industrially important process of unsaturated aldehydes conversion to unsaturated alcohols. For such processes, the supported Pt nanoparticles with the chemically modified surface represent a new type of highly effective catalysts. The key feature of such catalytic systems is the chemical modification of a surface aimed to the formation of surface structures providing the high selectivity of a reaction. However, the thermodynamic and kinetic parameters of elementary reactions on the modified surface, the effect of different ligands on the selectivity are poorly understood yet. In the present study, we studied the elementary processes and reactions occurring on the modified Pt surface considering the model sub-nanosize cluster Pt24. The size of the model cluster is about 8Å, which is close to the real-size catalysts particles of 12-15Å. The surface of the particle contains both the (111) and (100) planes of Pt crystal in approximately equal proportion. The elementary reactions studied with this model cluster are: (1) the physical adsorption of the organic ligands (n-C4H9SH) and molecular hydrogen; (2) chemical adsorption of the organic ligands with dissociation of SH bond and formation of covalent S-Pt bond on the surface; (3) dissociative adsorption of molecular hydrogen; (4) surface migration of the formed hydrogen atoms between the different sites of the Pt24 clusters; (5) physical adsorption of the acrolein and croton aldehyde on the surface; (6) hydrogenation of aldehyde by the hydrogen atoms adsorbed on the surface. In all the processes studied, the different coordination modes of the adsorbed species were considered, and the number of adsorbed molecules of organic ligands was varied from 1 to 8. It was shown that the energy of the molecular hydrogen coordination is varied from 1.4 to 5.9 kcal/mol, whereas the dissociative chemisorption energy is in a range from 9.4 to 17.2 kcal/mol depending on the coordination mode. At the same time, the single ligand physical coordination and chemisorption are characterized by the very close energy values– about 40 and 42-44 kcal/mol, respectively. It was found that the aldehyde group hydrogenation can occur via two different pathways with significantly different activation barriers. The corresponding estimated activation energies are about 14.8 kcal/mol for the direct transfer of H atom to oxygen, and 58.6 kcal/mol for the alternative two-step mechanism with H- transfer to carbon and further migration to oxygen. The effect of various coordination modes, number of adsorbed ligand molecules, and co-adsorbed reactant and products on the thermodynamic and kinetic parameters of the catalytic reactions are discussed. The study was supported by the Russian Foundation for Basic Research (Project No. 14-03-00585)

2047

Tetrahedral boron and aluminium crystal structures

Vitaliy V. Koval’, Ilya V. Getmanskii, Ruslan M. Minyaev

Southern Federal University

Abstract:

Structural stability of the tetrahedral and supertetrahedral molecular systems manifested by the sufficiently deep local minima on their PESs makes it possible to assume that the corresponding crystal systems are also kinetically stable structures. Such an assumption was first proven and borne out by Burdett and Lee [1] for the case of supertetrahedral diamond and Johnston and Hoffmann [2] for supercubane crystal structure. Results of our calculations (see Table 1) of geometric characteristics and properties are presented in two ways: in supermolecular approximation and with imposed periodic boundary conditions. In supermolecular aproximation optimized geometries С104H32, В104H32, В64С40H32 and В40С64H32, Al104H32, Si104H32 and Al64Si40H32 are presented designed on the basis of the diamond crystal lattice in which the carbon atoms are replaced by, respectively, B4, C4, and Al4 and Si4 tetrahedral units, calculated by the B3LYP/6-311+G** method. Despite the significant electron deficiency of the boron hydride B4H4, it has a stable structure with the core BB bonds lengths typical for single BB bonds of simple boranes. The bonds linking two neighboring tetrahedral fragments in В104H32 are substantially shorter than the corresponding bonds within these fragments. This fact finds its explanation in the results of the NBO and ELF-analyses which showed that the linking B-B bonds are formed as conventional 2c-2e σ-bonds, while the bonds within the B4 fragments are weaker three center – two electron 3c-2e bonds. The aluminium analog Al104H32 is also characterized by a local minimum on the corresponding PES and exhibits same type chemical bonding pattern as in boron systems. The Al-Al bond lengths do not differ much from single AlAl bonds in the known compounds of aluminum. Calculations with imposing periodic boundary conditions are shown the properties of previously unstudied supertetrahedral modifications of boron and aluminum and their mixed [X4Y4]∞ systems. The tetrahedral crystal structures are predicted to have conductor and semiconductor properties and lower density and hardness than diamond. In Figure 1 is presented schematic depiction of the supertetrahedral crystal structure [X4Y4]∞ (X,Y=B, C, Al, Si) where atom X and Y are marked by green and brown color, respectively. Authors thank the State Assignment of Russian Government for Research (Project N4.71.2014/K).

[1] J.K. Burdett, S. Lee, J Am Chem Soc. 1985, 107, 3063–3082 [2] R.L. Johnston, R. Hoffmann, J. Am. Chem. Soc., 1989, 111, 810–819.