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URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11800
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Item A pentacyclic triterpene from Maytenus imbricata: structure elucidation by X-ray crystallography(Structural Chemistry, 2006-02) Pimenta Jr., Alécio Antonio; Silva, Sílvia Ribeiro de Souza e; Silva, Grácia Divina de Fátima; Barbosa, Luiz Cláudio de Almeida; Ellena, Javier; Doriguetto, Antonio CarlosA pentacyclic triterpene, 3β,30-dihydroxy-lup-20(29)-ene, was isolated from the powder extract of Maytenus imbricata. The structure and stereochemistry of the compound were established by spectroscopic techniques and unambiguously determined by single crystal X-ray crystallography. The crystal structure shows one molecule in the asymmetric unit. The crystal packing is stabilized by O–H···O intermolecular hydrogen bonds, which give rise to infinite helical chains along the c unit cell axis. The intra-molecular geometry was analyzed using MOGUL, a knowledge base of molecular geometry derived from the Cambridge Structural Database (CSD).Item Preparation, crystal structure and spectroscopic characterization of nickel(II) complexes with dithiocarbimate derivated of sulfonamides(Polyhedron, 2006-07-10) Oliveira, Marcelo R. L.; Franca, Eduardo de Faria; Guilardi, Silvana; Andrade, Renato Pereira de; Lindemann, Renata Hernandez; Amim Jr., Jorge; Ellena, Javier; Bellis, Vito M. de; Rubinger, Mayura M. M.This work describes the syntheses of three compounds containing [Ni(RSO2N=CS2)2]^2 anions: (Bu4N)2[Ni(CH3CH2SO2N=CS2)2] (1), (Bu4N)2[Ni(4-IC6H4SO2N=CS2)2] (2) and (Bu4N)2[Ni(2,5-Cl2C6H3SO2N=CS2)2] (3). They were obtained in the crystalline form by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate (RSO2N=CS2K2) with nickel(II) chloride hexahydrate in methanol/water. Elemental analyses were consistent with the proposed formulae. UV–Vis and IR data are consistent with the formation of nickel–sulfur diamagnetic planar complexes. The 1H NMR and 13C NMR spectra showed the expected signals for the tetrabutylammonium cation and the dithiocarbimate moieties. Single crystal structure analyses showed that 1 crystallizes in the monoclinic space group P21/n, 2 crystallizes in the monoclinic space group P21/c and 3 crystallizes in the triclinic space group Pī. In these compounds the Ni. atom is coordinated to four S atoms in a distorted square plane geometry due to the asymmetric bidentade chelation by each ligand.