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In the title compound, C16H11F3O 2, the -pyran-one ring adopts an envelope conformation with the chiral C atom standing out of the ring plane. In the crystal, molecules are linked by C - H⋯O and C - H⋯F inter-actions.

Theoretical charge density analysis of the thioureido based compound 4-methyl-3-thiosemicarbazide (MeTSC) is used in this study with the aim to provide additional insight into electronic features of the thioureido sulfur acceptor and the corresponding D-H...S hydrogen bonding (D=N, C). The present work is motivated by our earlier experimental charge density study on the same compound that pointed out to a great flexibility of the thioureido S acceptor and its ability to adjust the lone pair electron density to the donor groups in simultaneous hydrogen bonding. Through the additional theoretical approach we were able to single out different fragments of MeTSC crystal and to carefully follow the changes in electron density properties of the S acceptors belonging to: isolated MeTSC monomers (i.e. two crystallographically independent molecules), eight D-H...S bonded dimers and MeTSC molecules placed in full crystal environment, where each S atom engages in four hydrogen bonds. Deformation density of the sulfur's lone electron pair, topological properties of D-H...S interactions and electrostatic potential are here examined in order to comprehend the mutual influence and potential cooperative effects of the four simultaneously formed interactions to each of the S acceptors. The hydrogen bonding involving thioureido S acceptor is also investigated in terms of the energetic properties of the eight real MeTSC dimers existing in the crystal structure, and additional systems MeTSC/MeOH and acetone/MeOH. The latter systems are designed with the purpose of direct comparison and ranking of interactions involving thioureido S to those involving more conventional, carbonyl O acceptor. Energetic features were thoroughly studied through electrostatic interactions energies (XD2006), cohesive energies (CRYSTAL09) and ab initio approach employing the coupled-cluster single S and doubles augmented by a perturbational correction for connected triple excitations (CCSD(T)) method.

U ovoj doktorskoj disertaciji izloženi su rezultati analize eksperimentalno i teorijski dobijene raspodele gustine naelektrisanja dva derivata tiosemikarbazida, 4-metil-3-tiosemikarbazida (MeTSC) i 4-metil-3-tiosemikarbazon 2-piridinformamida (TSC4). Analiza eksperimentalno dobijene gustine naelektrisanja je zasnovana na preciznim podacima dobijenim difrakcijom rendgenskog zračenja visoke rezolucije. Teorijska istraživanja bazirana su na teorijskim strukturnim faktorima dobijenim primenom programa CRYSAL09 polazeći od geometrije molekula određene nakon multipol utačnjavanja eksperimentalno dobijene gustine naelektrisanja. Za opisivanje eksperimentalne i teorijske ukupne elektronske gustine korišćen je Hansen-Coppens-ov multipol-model. Takođe je urađena i topološka analizahemijskih veza i interakcija i ispitivana su elektrostatička svojstva atoma sumpora. Analizom eksperimentalne gustine naelektrisanja kristalnih struktura MeTSC i TSC4 uočeno je da deformaciona gustina slobodnih elektronskih parova S atoma ima oblik torusa, da je unutar njega raspodela elektronske gustine nehomogena i da položaj samog torusa može biti ortogonalan (SalTSC) ili pod uglom (MeTSC, TSC4). Na osnovu raspodele deformacione gustine i elektrostatičkog potencijala, kao i na osnovu topološke analize ukupne eksperimentalne gustine naelektrisanja ρktv i njenog Laplasijana ∇2ρktv zaključeno je da atom sumpora ima izrazitu fleksibilnost i sposobnost da prilagodi svoju elektronsku gustinu slobodnih elektronskih parova prostornom rasporedu donornih grupa koje učestvuju u interakcijama sa S akceptorom. U kristalnim strukturama MeTSC i TSC4 utvrđeno je da S atom istovremeno gradi četiri, odnosno prosečno šest međumolekulskih interakcija. U cilju upotpunjavanja eksperimentalnih rezultata analizirana je teorijski dobijena gustina naelektrisanja oba molekula, a zatim su ispitivane karakteristike sumpora kao akceptora i to u sistemima različite složensti polazeći od izolovanih monomera, preko izdvojenih di, In this dissertation the analysis of the experimental and theoretically obtained electron density of two derivatives of thiosemicarbasides, 4-methyl-3-thiosemicarbaside (MeTSC) and 4-methyl-3-thiosemikabazone 2-piridinformamide (TSC4) are presented. The analysis of experimentally obtained electron density is based on accurate X-ray diffraction data of high resolution. Theoretically calculated electron densities are obtained from periodic quantum mechanical calculation using CRYSTAL09 and the accurate structural parameters from high resolution X-ray experiment. For the description of the theoretical and experimental electron density the Hansen-Coppens multipol model was used. Further topological analysis of chemical bonds and interactions was performed in order to explain the electrostatic properties of sulfur. In this work it has been observed that in the experimentally obtained electron density of the MeTSC and TSC4 crystal structures, the deformational electron density of sulfur free electron pairs forms a toroidal shape. Further, this torus is not homogeneously filled but shows pronounced local accumulations and its position can be either orthogonal (like in SalTSC) or tilted (MeTSC, TSC4). Based on the distribution of the deformational electron density and electrostatic potential, as well as the topological analysis of the total electron density ρktv and its Laplasian ∇2ρktv it can be concluded that the S atom has a remarkable flexibility and ability to adapt his deformation electron density of free electron pairs into toruses corresponding to the position of donor groups surrounding him. In the crystal structures of MeTSC and TSC4 it was determined that the S atom participates in four and six interactions, respectively. In order to supplement the experimentally obtained results a theoretically calculated electron density of both molecules (MeTSC and TSC4) was performed and the properties of the S atom as a hydrogen acceptor have been studied. The analysis was p

The L-phenylalanine methyl ester derivative of dexamethasone-derived cortienic acid (DF) was synthesized and its crystal structure characterized by the X-ray diffraction method. The crystal system is orthorhombic with space group P2(1)2(1)2(1) and cell constants a = 8.2969(3) angstrom, b = 18.9358(8) angstrom, c = 20.0904(6) angstrom, V = 3156.4(2) angstrom(3) and Z = 4. Ring A of the steroid nucleus and phenyl ring in the 17 beta-side chain are almost planar. Rings B and C have a slightly distorted chair conformation, whereas ring D has an envelope conformation. The packing of DF is characterized by a network of intermolecular hydrogen bonds involving the O4 atom from one side of the steroid nucleus and O1 and F1 atoms from the other side as hydrogen bond acceptors. Apart from the intermolecular hydrogen bonds in the crystal packing, there are also numerous intramolecular hydrogen bonds of the N-H center dot center dot center dot O, C-H center dot center dot center dot O and C-H center dot center dot center dot F type. The local anti-inflammatory activity of DF was evaluated using the croton oil-induced ear oedema test. This derivative achieved maximal inhibition of ear oedema at significantly lower concentration in comparison with dexamethasone.

In the title compound, [Fe(C8H7N3)(H2O)(4)]SO4, the central Fe-II ion is octahedrally coordinated by two N atoms from the bidentate 2-(pyridin-2-yl)-1H-imidazole ligand and by four O atoms of the aqua ligands. The largest deviation from the ideal octahedral geometry is reflected by the small N-Fe-N bite angle of 76.0 (1)degrees. The Fe-N coordination bonds have markedly different lengths [2.1361 (17) and 2.243 (2) angstrom], with the shorter one to the pyrimidine N atom. The four Fe-O coordination bond lengths vary from 2.1191 (18) to 2.1340 (17) angstrom. In the crystal, the cations and anions are arranged by means of medium-strength O-H center dot center dot center dot O hydrogen bonds into layers parallel to the ab plane. Neighbouring layers further interconnect by N-H center dot center dot center dot O hydrogen bonds involving the imidazole fragment as donor group to one sulfate O atom as an acceptor. The resulting three-dimensional network is consolidated by C-H center dot center dot center dot O, C-H center dot center dot center dot pi and pi-pi interactions.

Sulfur atom is generally considered as a weak hydrogen bonding acceptor which is mostly explained by its low electronegativity. This is a background, and motivation, for this study that aims to provide additional insight into electronic features of the sulfur acceptor. The analysis of sulfurs electronic features uses high-resolution, low-temperature X-ray diffraction datasets on 4-methyl-3-thiosemicarbazide (MeTSC) and salicylaldehyde thiosemicarbazone (SalTSC). The total electron density distribution was modeled using Hansen-Coppens multipole model. The fact that MeTSC crystallizes with two crystallographically independent (but chemically equivalent) molecules, engaging in partly different D-H center dot center dot center dot S interactions, has, quite conveniently, enabled the examination of fine effects of the D-H center dot center dot center dot S interactions on the lone pairs electron density of the two S acceptors. The deformation density distribution, topological analysis of the total experimental charge density rho(r) and its Laplacian (del(2)rho(r)), and, finally, electrostatic potential all point to the great flexibility of the S acceptor and its ability to adjust to the spatial distribution of the interacting donor groups. Toroidal accumulation of the S lone pairs electron density, strong value of the negative electrostatic potential even at a distance of 3.1 angstrom from the S nucleus, and interpenetration of the van der Waals spheres for the donor and S acceptor atoms are all an indication of sulfurs capacity to simultaneously engage in a greater number of interactions than conventional acceptors such as O and N.