T. Veszprémi

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Borane complexes of aziridine, phosphirane, cyclopropylamine, cyclopropylphosphine, cyclopropylmethylamine, and cyclopropylmethylphosphine have been prepared by the reaction at low temperatures of a borane complex or diborane on the free phosphine or amine. The products characterized by NMR spectroscopy and mass spectrometry have then been investigated by(More)
Several C5-substituted 2,4,6-triaminopyrimidine derivatives and their HBF4 salts were synthesized to study the carbon protonation of the pyrimidine ring. NMR investigations in DMSO-d6 prove experimentally that, in addition to the usual protonation at N1, the compounds can be protonated at C5 as well. We present several new stable cationic sigma-complexes in(More)
Conceptual DFT gives sharp definitions for many long-known, but rather vaguely defined chemical concepts. In this study DFT-based reactivity indices are applied to silylenes in order to elucidate the relationships among their properties: stability, acid-base, and spin properties, nucleophilicity and electrophilicity. On the basis of a detailed, comparative(More)
The regioselectivity of ring-forming radical reactions is investigated within the framework of the so-called spin-polarized conceptual density functional theory. Two different types of cyclizations were studied. First, a series of model reactions of alkyl- and acyl-substituted radicals were investigated. Next, attention was focused on the radical cascade(More)
This paper presents an approach for obtaining accurate interaction energies at the density functional theory level for systems where dispersion interactions are important. This approach combines Becke and Johnson's [J. Chem. Phys. 127, 154108 (2007)] method for the evaluation of dispersion energy corrections and a Hirshfeld method for partitioning of(More)
A detailed investigation of the electrophilic and nucleophilic character of singlet silylenes and germylenes, divalent compounds of silicon and germanium, respectively, substituted by first- and second-row elements is presented. In a first part, the Lewis acid properties of these compounds were studied through their complexation reaction with the Lewis(More)
The possible synthesis of hexasilabenzene was studied as the consecutive reaction of three disilyne units in order to find a suitable substituent. Although there is a reaction pathway which leads to hexasilabenzene in the case of hydrogen (A) and phenyl (B) groups, and it is thermodynamically and kinetically favourable, the reaction can easily proceed(More)
Size matters! The electronic structure and size-dependent stability of neutral and cationic scandium-doped copper clusters have been investigated by mass spectrometric studies (for the cations) and also quantum chemical computations. The proposed reaction paths ultimately lead to the most stable Frank-Kasper-shaped Cu(16)Sc(+) cluster (shown here), which(More)
Density functional theory calculations demonstrate that the global minimum of the Cu(7)Sc potential energy surface is a seven-membered ring of copper atoms with scandium in its center, yielding a planar D(7) (h) structure. Nucleus-independent chemical shifts [NICS(1)(zz) and NICS(2)(zz)] show that this cluster has aromatic character, which is consistent(More)
This work presents a real three-dimensional (3D) solution of the scalar Helmholtz-equation for VCSELs with finite volume method (FVM). The advantage of this formulation is that the order and structure of the system matrix can be reduced compared to vectorial finite element approach, and thus the feasible problem size can be significantly increased.(More)