Sławomir Wojtulewski

Ab initio and AIM studies on intramolecular dihydrogen bonds

Abstract Ab inito calculations on molecules with intramolecular dihydrogen bonds have been performed at MP2/6-311++G(d,p) level of theory. The O–H bond for these systems is the proton donator and the H–B bond of BH3− group is the acceptor within B–H⋯H–O H-bridge. Different geometrical, energetic and topological parameters derived from the theory of Bader have been studied. The correlation analysis shows that there is no the meaningful delocalization of electrons within the ring formed by the intramolecular H-bridge. The properties of the bond critical points of H+δ⋯−δH contacts and the properties of the ring critical points are useful parameters for the description of the unconventional H-bond analysed in this study.

DFT and AIM studies on two-ring resonance assisted hydrogen bonds

Abstract DFT calculations on molecules with intramolecular hydrogen bonds have been performed at B3LYP/6-311++G(d,p) level of theory. The investigated 2,4-dihydroxybut-2-ene-4-dial molecule and its derivatives contain two intramolecular H-bonded rings. Each ring is the resonance-assisted system. The results of calculations show that two rings within the same molecule do not cause an increase of the resonance effect. It is shown that the topological parameters such as features of bond critical points and ring critical points may be treated as measures of H-bond strength.

Unconventional F–H⋯π hydrogen bonds — ab initio and AIM study

Abstract Ab initio HF/6-311++G∗∗ and MP2/6-311++G∗∗ calculations on complexes of hydrogen fluoride with acetylene and its derivatives have been performed to study the unconventional F–H⋯π hydrogen bonding. The results show that topological parameters of the Bader theory correlate better with H-bond strength than geometrical parameters. The changes of proton donating molecule (HF) due to dimerization also reflect well the H-bond strength.

Theoretical (in B3LYP/6-3111++G** level), spectroscopic (FT-IR, FT-Raman) and thermogravimetric studies of gentisic acid and sodium, copper(II) and cadmium(II) gentisates.

The DFT calculations (B3LYP method with 6-311++G(d,p) mixed with LanL2DZ for transition metals basis sets) for different conformers of 2,5-dihydroxybenzoic acid (gentisic acid), sodium 2,5-dihydroxybenzoate (gentisate) and copper(II) and cadmium(II) gentisates were done. The proposed hydrated structures of transition metal complexes were based on the results of experimental findings. The theoretical geometrical parameters and atomic charge distribution were discussed. Moreover Na, Cu(II) and Cd(II) gentisates were synthesized and the composition of obtained compounds was revealed by means of elemental and thermogravimetric analyses. The FT-IR and FT-Raman spectra of gentisic acid and gentisates were registered and the effect of metals on the electronic charge distribution of ligand was discussed.

Performance of Moller-Plesset second-order perturbation theory and density functional theory in predicting the interaction between stannylenes and aromatic molecules.

The performances of Møller-Plesset second-order perturbation theory (MP2) and density functional theory (DFT) have been assessed for the purposes of investigating the interaction between stannylenes and aromatic molecules. The complexes between SnX2 (where X = H, F, Cl, Br, and I) and benzene or pyridine are considered. Structural and energetic properties of such complexes are calculated using six MP2-type and 14 DFT methods. The assessment of the above-mentioned methods is based on the comparison of the structures and interaction energies predicted by these methods with reference computational data. A very detailed analysis of the performances of the MP2-type and DFT methods is carried out for two complexes, namely SnH2-benzene and SnH2-pyridine. Of the MP2-type methods, the reference structure of SnH2-benzene is reproduced best by SOS-MP2, whereas SCS-MP2 is capable of mimicking the reference structure of SnH2-pyridine with the greatest accuracy. The latter method performs best in predicting the interaction energy between SnH2 and benzene or pyridine. Among the DFT methods, ωB97X provides the structures and interaction energies of the SnH2-benzene and SnH2-pyridine complexes with good accuracy. However, this density functional is not as effective in reproducing the reference data for the two complexes as the best performing MP2-type methods. Next, the DFT methods are evaluated using the full test set of SnX2-benzene and SnX2-pyridine complexes. It is found that the range-separated hybrid or dispersion-corrected density functionals should be used for describing the interaction in such complexes with reasonable accuracy.

Spectroscopic (FT-IR, FT-Raman and 1H and 13C NMR) and theoretical in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels study of benzenesulfonic acid and alkali metal benzenesulfonates

The FT-IR, FT-Raman and NMR ((1)H and (13)C) spectra of benzenesulfonic acid as well as lithium, sodium, potassium, rubidium and caesium benzenesulfonates were registered, assigned and compared. The molecular structures of ligand and alkali metal salts were discussed. On the basis of quantum mechanical calculations in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels the geometric parameters, infrared spectra, NMR spectra, the magnetic and geometric aromaticity indices for acid and alkali metal benzenesulfonates and benzoates were obtained. The effect of alkali metal ions on the electronic charge distribution of benzenesulfonic acid was studied and compared with the alkali metal benzoates and benzoic acid.

Magnetic nanoparticles with chelating shells prepared by RAFT/MADIX polymerization

In this study, the preparation of multifunctional materials based on magnetic nanoparticles (MNP) and original thiosemicarbazide derivatives is presented. The synthesized nanohybrids consist of an iron oxide core and a polymeric shell, which possesses the ability to complex metal ions. They exhibit superparamagnetic properties and can thus be easily separated from complex mixtures using an external magnetic field (facile separation, purification, and recyclability). Synthesized carbamohydrazonothioate derivatives were polymerized on dithiocarbonate-coated MNPs using the RAFT/MADIX (reversible addition–fragmentation transfer/macromolecular design by interchange of xanthates) method. Three types of nanohybrids were obtained and their physicochemical properties were investigated. The ability of nanohybrids to complex palladium(II) ions and the spectroscopic properties of the obtained materials were studied. In addition, the hemolytic activity tests of polymer-coated particles were performed in order to confirm their potential in biomedical applications.

(2R)-8-Benzyl-2-[(S)-hy­droxy(phen­yl)meth­yl]-8-aza­bicyclo­[3.2.1]octan-3-one

The crystal of the title compound, C21H23NO2, was chosen from a conglomerate formed by a racemic mixture. An intramolecular hydrogen bond is formed between hydroxy group and heterocyclic N atom of the azabicyclo[3.2.1]octan-3-one system. The crystal structure is stabilized by C—H⋯O interactions between aliphatic C—H groups and the carbonyl O atom. For the title chiral crystal, the highly redundant and accurate diffraction data set collected with low energy copper radiation gave a Flack parameter of 0.12 (18) for anomalous scattering effects originating from O atoms.

Carbamohydrazonothioate derivative—experimental and theoretical explorations of the crystal and molecular structure

AbstractThe structural studies of carbamohydrazonothioate derivative and its hydrochloride solvate are the aim of hereunder presented research. The combination of the crystallographic technics and the Hirshfeld surface analysis allows to describe the net of the hydrogen bonds as well as other non-covalent interactions within the crystal structures. The crystal structures of 4-ethenylbenzyl N′-[(E)-phenylmethylidene] carbamohydrazonothioate (CHT) and CHT hydrochloride solvate are built of bent and linear conformers of the carbamohydrazonothioate derivative, respectively. The theoretical calculations indicate that the alteration of the conformation is possible. While the geometry of the bent conformers allows the crystal structure to propagate, the linear conformation does not encourage formation of the intermolecular interactions between CHT molecules. Therefore, in the latter case, the chloride ions and methanol play the role of the molecular glue. In both crystal structures, the dominant is H···H interaction; thus, the dispersion energy is an important factor in intermolecular interactions. The theoretical calculations for single molecules and dimers of CHT show the negligible influence of the crystal packing on molecular conformation and dimer formation, when the dispersion energy correction is applied.

N-Oxide–N-oxide interactions and Cl...Cl halogen bonds in pentachloropyridine N-oxide: the many-body approach to interactions in the crystal state

Pentachloropyridine N-oxide, C5Cl5NO, crystallizes in the monoclinic space group P21/c. In the crystal structure, molecules are linked by C-Cl...Cl halogen bonds into infinite ribbons extending along the crystallographic [100] direction. These molecular aggregates are further stabilized by very short intermolecular N-oxide-N-oxide interactions into herringbone motifs. Computations based on quantum chemistry methods allowed for a more detailed description of the N-oxide-N-oxide interactions and Cl...Cl halogen bonds. For this purpose, Hirshfeld surface analysis and the many-body approach to interaction energy were applied.