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Crystal, molecular and electronic structure of (5S,8aS)-5-methyl-4,6,7,8,8a,9-hexahydrothieno-[ 3,2-f] indolizinium iodide

Abstract

The molecules of the title compound, C11H16NS·I, crystallize as single enantiomer with two stereogenic centre, their absolute configuration were confirmed by anomalous dispersion effects in diffraction measurements on the crystals. The conformation of the pyrrolidine ring is close to that of an envelope, with the flap atom N1 displaced by 0.661 (2) A from the plane of the oder remaining four atoms. The central six-membered ring of the indolizine moiety adopt a half-chair conformation with atom C5 displaced by -0.686 (2) Å from the plane of the oder remaining five atoms. The crystal structure of the title compound is stabilized by C-H···I···H-C hydrogen interactions.

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Crystal, molecular and electronic structure of (3aS,4S,9aS,9bR)-4-ethyl-2,2-dimethylhexahydro-[1,3]dioxolo[4,5-g] indolizin-7(3aH)-one

Abstract

Molecules of the title compound, C13H21NO3, crystallize as single enantiomers with four stereogenic centres, their absolute configuration were confirmed by anomalous dispersion effects determined by diffraction measurements on the crystals. Conformations of the pyrrolidine and 1,3-oxolane rings are close to that of an envelope, with the flap atoms displaced by −0.205 (1) and −0.449 (1) Å, respectively, from the plane of the other remaining four atoms. The central six-membered ring of the indolizine moiety adopts a nearly perfect boat conformation, with two atoms displaced by 0.575 (1) and 0.603 (1) Å from the plane of the other remaining four atoms. Crystal structure of the title compound is stabilized by C−H···O hydrogen interactions.

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Mössbauer spectroscopy of reduced forms of a Fe-tetraphenylporphyrine complex

. Guilard (Eds.), The porphyrin handbook (Vol. 6, pp. 231–256). San Diego: Academic Press. 4. Gurinovich, G. P., Gurinovich, I. F., Ivashin, N. V., Sinyakov, G. N., Shulga, A. M., Terekhov, S. N., Filatov, I. V., & Dziliński, K. (1988). Electronic structure of metalloporphyrin π-anions. J. Mol. Struct. , 172 , 317–343. DOI: 10.1016/0022-2860(88)87026-1. 5. Fukuzumi, S. (2003) Electron transfer chemistry of porphyrins and metalloporphyrins. In K. M. Kadish, K. M. Smith & G. Guilard (Eds.), The porphyrin handbook (Vol. 8, pp. 115–151). Amsterdam: Academic Press

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Mössbauer study of a tetrakis (pentafluorophenyl) porphyrin iron (III) chloride in comparison with the fluorine unsubstituted analogue

Abstract

Mössbauer investigations, in association with density functional theory (DFT) calculations, have been conducted for the molecular and electronic structures of iron (III) [tetrakis (pentafluorophenyl)] porphyrin chloride [(F20TPP)Fe:Cl], as a Fe(III)-tetraphenylporphyrin complex containing chloride axial ligand and substituted hydrogen atoms by fluorine ones in the four phenyl rings, in comparison with its fluorine unsubstituted analogue [(TPP)Fe:Cl]. It was found that the parameters of Mössbauer spectra of both complexes are close to one another, and correspond to the high-spin state of Fe(III) ions, but they show the different temperature dependence and the quadrupole doublets in Mössbauer spectra show different asymmetry at low temperatures. Results of DFT calculations are analyzed in the light of catalytic activity of the halogenated complex.

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DFT Investigation of Structural and Electronic Properties of Modified PZT

. 2004 , 3 , 164-170. 12. Watson, G.W.; Parker, S.C.; Kresse, G. Ab initio calculation of the origin of the distortion of α-PbO. Phys. Rev. B. 1999 , 59 , 8481-8486. 13. Franchini, M.; Philipsen, P.; van Lenthe, E.; Visscher, L. Accurate Coulomb Potentials for Periodic and Molecular Systems through Density Fitting. J. Chem. Theory Comput . 2014 , 10 , 1994–2004. 14. Liu, S.-Y.; Shao, Q.-S.; Yu, D.-S.; Lü, Y.-K.; Li, D.-J.; Li, Y.; Cao, M.-S. First-principles study on the geometric and electronic structures and phase transition of PbZr 1−x

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Crystal and electronic structure, N–H⋯N and C–H⋯O interactions in novel spiro-[chroman-chromene]-carboxylate

Abstract

We report here the structure of new spiro-derivative, namely methyl (2R,4R)-4-(5-methylthiazol- 2-ylamino)spiro[chroman-2,2’-chromene]-3’-carboxylate, C23H20N2O4S, which crystallizes as racemate in the space group P-1. In this compound, the chromanone moiety consists of a benzene ring fused with a sixmembered heterocyclic ring which adopts a distorted half-chair conformation. The molecules are linked by a combination of N–H⋯N hydrogen bonds and weak C–H⋯O, C-H⋯S, C-H⋯π, inter- and intramolecular interactions resulting in a two-dimensional network in the crystal structure.

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Crystal, molecular and electronic structure of (5S,11R,11aS)-11-hydroxy-5-methyl-1,2,3,4,5,6,11,11a-octahydropyrido[1,2-b]isoquinolin-5-ium iodide

Abstract

The title compound, C14H20INO, is a molecule with three stereogenic centres. It absolute configuration was derived from the synthesis and confirmed by structure determination (AD, Flack (Parsons’) parameter: 0.031 (8)). The expected stereochemistry of atoms N1 was confirmed to be S, C5 was confirmed to S, C6 was confirmed to R. The central N-heterocyclic ring is not planar and adopts a half-chair conformation. A calculation of least-squares planes showed that these rings are puckered in such a manner that the five atoms: C5, C6, C7, C12 and C13 (the second ring: C1, C2, C3, C4, C5 and N1) are planar, while atom N1 is displaced from these plane with the out-of-plane displacement of −0.694 (4) and −0.670 (5) Å in the second ring, respectively. Dihedral angle between the planes of the central N-heterocyclic rings is 23.4 (2)°. Crystal structure is also stabilized by C—H···O hydrogen interactions.

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Quantum-chemical study of the active sites of camptothecin through their Cu(II) coordination ability

Abstract

The structures of camptothecin (CPT) lactone form and its complexes with Cu(II) were optimized at B3LYP/6-311G* level of theory. Their electronic structures were evaluated via QTAIM topological analysis of electron density and Mulliken population analysis. Stability, electron density distribution and geometrical factors of the optimized systems were compared. Both CPT nitrogen atoms show lower affinity to Cu(II) compared to the oxygen ones. Both the oxygen atom in the CPT lactone ring and the one in the neighbouring carbonyl group show the highest affinity to Cu(II) and the highest stability of Cu-CPT complexes which indicates the most probable CPT reaction sites.

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On local aromaticity of selected model aza-[n]circulenes (n = 6, 7, 8 and 9): Density functional theoretical study

Abstract

A computational study using density functional theory is reported for selected model aza[n]circulenes (n = 6, 7, 8 and 9) and their derivatives consisting of pyrrole and benzene units. Local aromaticity of central rings was discussed and analyzed using theoretical structural indices. Depending on their molecular structures, energies of the highest occupied and lowest unoccupied molecular orbitals change from –5.23 eV to –4.08 eV and from –1.97 eV to –0.41 eV, respectively. Based on B3LYP calculated optimal geometries, electronic structure of molecules and their charge transport properties resulted in the suggestion of three planar molecules containing three or four pyrrole units as potential candidates for p-type semiconductors. Hole drift mobilities for ideal stacked dimers of these potential semiconductors were calculated and they range from 0.94 cm2·V−1·s−1 to 7.33 cm2·V−1·s−1.

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Crystallographic characterization of a novel spiro-[chroman-chromene]-carboxylate

Abstract

We report here the crystal and electronic structure of a new spiro-derivative, namely methyl (2R,4S)- 4-(benzothiazol-2-ylamino)-8,8´-dimethoxyspiro[chroman-2,2´-chromene]-3´-carboxylate (I), C28H24N2O6S, which crystallizes as racemate in the space group C2/c. In this compound, the chromanone moiety consists of a benzene ring fused with a six-membered heterocyclic ring which adopts a distorted half-chair conformation. The molecules are linked by a combination of N-H∙∙∙N hydrogen bonds and weak C-H∙∙∙O, C-H∙∙∙S, C-H∙∙∙ π, inter- and intra-molecular interactions resulting in a two-dimensional network in the crystal structure.

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