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Molecular crystals exhibiting polar symmetry are important paradigms for developing new electrooptical materials. Though accessing bulk polarity still presents a significant challenge, in some cases it may be rationalized as being associated with the specific molecular shapes and symmetries and subtle features of supramolecular interactions. In the crystal structure of 3,5,7-trinitro-1-azaadamantane, C9H12N4O6, the polar symmetry of the molecular arrangement is a result of complementary prerequisites, namely the C3v symmetry of the molecules is suited to the generation of polar stacks and the inherent asymmetry of the principal supramolecular bonding, as is provided by NO2(lone pair)...NO2(π-hole) interactions. These bonds arrange the molecules into a trigonal network. In spite of the apparent simplicity, the structure comprises three unique molecules (Z' = 1/3 + 1/3 + 1/3), two of which are donors and acceptors of three N...O interactions and the third being primarily important for weak C-H...O hydrogen bonding. These distinct structural roles agree with the results of Hirshfeld surface analysis. A set of weak C-H...O and C-H...N hydrogen bonds yields three kinds of stacks. The orientation of the stacks is identical and therefore the polarity of each molecule contributes additively to the net dipole moment of the crystal. This suggests a special potential of asymmetric NO2(lone pair)...NO2(π-hole) interactions for the supramolecular synthesis of acentric materials.1-(Chloromethyl)-3-nitrobenzene, C7H6NClO2, and 1-(bromomethyl)-3-nitrobenzene, C7H6NBrO2, were chosen as test compounds for benchmarking anisotropic displacement parameters (ADPs) calculated from first principles in the harmonic approximation. Crystals of these compounds are isomorphous, and theory predicted similar ADPs for both. read more In-house diffraction experiments with Mo Kα radiation were in apparent contradiction to this theoretical result, with experimentally observed ADPs significantly larger for the bromo derivative. In contrast, the experimental and theoretical ADPs for the lighter congener matched reasonably well. As all usual quality indicators for both sets of experimental data were satisfactory, complementary diffraction experiments were performed at a synchrotron beamline with shorter wavelength. Refinements based on these intensity data gave very similar ADPs for both compounds and were thus in agreement with the earlier in-house results for the chloro derivative and the predictions of theory. We speculate that strong absorption by the heavy halogen may be the reason for the observed discrepancy.A ternary derivative of Li3Bi with the composition Li3-x-yInxBi (x ≃ 0.14, y ≃ 0.29) was produced by a mixed In+Bi flux approach. The crystal structure adopts the space group Fd-3m (No. 227), with a = 13.337 (4) Å, and can be viewed as a 2 × 2 × 2 superstructure of the parent Li3Bi phase, resulting from a partial ordering of Li and In in the tetrahedral voids of the Bi fcc packing. In addition to the Li/In substitutional disorder, partial occupation of some Li sites is observed. The Li deficiency develops to reduce the total electron count in the system, counteracting thereby the electron doping introduced by the In substitution. First-principles calculations confirm the electronic rationale of the observed disorder.Iodination of Ph2Te2Se by molecular iodine is directed towards the Te atom and yields diiodo[(phenyltellanyl)selanyl]-λ4-tellanylbenzene, PhTeSeTeI2Ph or C12H10I2SeTe2. The molecule can be considered as a chimera of PhTeSeR, PhTeSeTePh and R'TeI2Ph fragments. The crystal structure features a complex interplay of the supramolecular synthons Te...π(Ph), Se...Te and I...Te, combining molecules into a three-dimensional framework. Their combination affords long-range supramolecular synthons which are fused in a way resembling the mythological chimera and could be defined as chimeric supramolecular synthons. The energies of the intermolecular interactions have also been calculated and analyzed.The structure of the new salt 1-(o-tolyl)biguanidium chloride, C9H14N5+·Cl-, has been determined by single-crystal X-ray diffraction. The salt crystallizes in the monoclinic space group C2/c. In this structure, the chloride and biguanidium hydrophilic ions are mostly connected to each other via N-H...N and N-H...Cl hydrogen bonds to form layers parallel to the ab plane around y = 1/3 and y = 2/3. The 2-methylbenzyl groups form layers between these layers around y = 0 and y = 1/2, with the methyl group forming C-H...π interactions with the aromatic ring. Intermolecular interactions on the Hirshfeld surface were investigated in terms of contact enrichment and electrostatic energy, and confirm the role of strong hydrogen bonds along with hydrophobic interactions. A correlation between electrostatic energy and contact enrichment is found only for the strongly attractive (N-H...Cl-) and repulsive contacts. Electrostatic energies between ions reveal that the interacting biguanidium cation pairs are repulsive and that the crystal is maintained by attractive cation...Cl- dimers. The vibrational absorption bands were identified by IR spectroscopy.The crystal structures of six halobismuth(III) salts of variously substituted aminopyridinium cations display discrete mononuclear [BiCl6]3- and dinuclear [Bi2X10]4- anions (X = Cl or Br), and polymeric cis-double-halo-bridged [BinX4n]n- anionic chains (X = Br or I). Bis(2-amino-3-ammoniopyridinium) hexachloridobismuth(III) chloride monohydrate, (C5H9N3)2[BiCl6]Cl·H2O, (1), contains discrete mononuclear [BiCl6]3- and chloride anions. Tetrakis(2-amino-3-methylpyridinium) di-μ-chlorido-bis[tetrachloridobismuth(III)], (C6H9N2)4[Bi2Cl10], (2), tetrakis(2-amino-3-methylpyridinium) di-μ-bromido-bis[tetrabromidobismuth(III)], (C6H9N2)4[Bi2Br10], (3), and bis(4-amino-3-ammoniopyridinium) di-μ-chlorido-bis[tetrachloridobismuth(III)] dihydrate, (C5H9N3)2[Bi2Cl10]·2H2O, (4), incorporate discrete [Bi2X10]4- anions (X = Cl or Br), while catena-poly[2,6-diaminopyridinium [[cis-diiodidobismuth(III)]-di-μ-iodido]], (C5H8N3)[BiI4]n, (5), and catena-poly[2,6-diaminopyridinium [[cis-dibromidobismuth(III)]-di-μ-bromido]], (C5H7N2)[BiBr4]n, (6), include [BinX4n]n- anionic chains (X = Br or I).
Homepage: https://www.selleckchem.com/products/Adrucil(Fluorouracil).html
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