Richard Ševčík

The synthesis and characterization of three oxidized derivatives of bis(diphenylphosphino)pyridine and their Sn(IV) complexes

The synthesis and spectroscopic characterization of three chalcogenophosphoryl ligands derived from pyridine is reported. The synthesis was based on the oxidation of C5H3N(PPh2)(2) by elemental sulfur and selenium, and hydrogen peroxide. As a part of our study on the coordination chemistry of the ligands, three new Sn(IV) complex cations of the general formula {[Ph2P(E)-C5H3N-P(E)Ph-2]SnCl3}(+) (E = O, S, Se) were also synthesized. All compounds were characterized by P-31 NMR and X-ray crystallography. The organic ligands are tridentate, with both chalcogens and nitrogen involved in chelation. The cations show an approximate octahedral core geometry and are paired with either SnCl5- or SnCl5(OH2)(-) anions.

Acid-base properties, FT-IR, FT-Raman spectroscopy and computational study of 1-(pyrid-4-yl)piperazine.

We report the vibrational spectral analysis was carried out using FT-IR and FT-Raman spectroscopy for 1-(pyrid-4-yl)piperazine (PyPi). Single crystals of PyPi suitable for X-ray structural analysis were obtained. The acid-base properties are also reported. PyPi supported on a weak acid cation-exchanger in the single protonated form and this system can be used efficiently as the solid supported analogue of 4-N,N-dimethyl-aminopyridine. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule and with the molecular electrostatic potential map was applied for the reactivity assessment of PyPi molecule toward proton, electrophiles and nucleopholes as well. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The calculated first hyperpolarizability of PyPi is 17.46 times that of urea.