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51.
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53.
de León ME Pérez-García B Márquez-Guzmán J Mendoza-Ruiz A 《Micron (Oxford, England : 1993)》2008,39(8):1351-1362
The morphogenesis of the sexual phase of seven species of Thelypteris subg. Cyclosorus (Thelypteridaceae) is described and compared. Spores of all species are monolete, ellipsoid and have positive photoblastism. They have Vittaria-type germination, germinal filaments are short and uniseriate, and Aspidium-type development. Adult gametophytes are spatulate-cordiform, and have wide wings with numerous glandular, marginal and superficial hairs. Antheridia have a narrow or widened basal cell, an undivided annular cell, and an opercular cell; antherozoids are liberated through three mechanisms. Archegonia have short necks and four triangular cells on the neck's mouth. The sporophyte's first leaf is lobed, with open dichotomous veins, glandular hairs similar to those of the gametophyte, and anomocytic stomata. Differences observed between the studied species are: spore size; ornamentation of the perispore; germination and emergence periods; size of hairs; developmental period of gametangia; and antherozoid liberation mechanisms through total detachment of the operculum, partial detachment of the operculum, and development of an apical pore through tearing of the operculum. These taxonomically valuable characters, combined with the sporophyte characteristics, can be useful tools in the identification of the species studied to the subg. Cyclosorus. 相似文献
54.
Jos Mahía Miguel A. Maestro Miguel Vzquez Manuel R. Bermejo Ana M. Gonzlez Marcelino Maneiro 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(3):347-348
The structure of the title compound, C30H30N4O4S2, is highly conditioned in the solid state by two strong N—H?N interactions. The values of the distances between the aminic N atoms [5.865 (3) Å] and the iminic N atoms [2.930 (4) Å], in conjunction with the long distance between the S atoms of the two tosyl groups [7.673 (1) Å], suggest that when the molecule acts as a ligand it will provide a single cavity for N4 coordination to the metal centre. 相似文献
55.
Concepción Foces-Foces Carlos Cativiela María Mar Zurbano Isabel Sobrados Nadine Jagerovic José Elguero 《Journal of chemical crystallography》1996,26(8):579-584
The crystal and molecular structure of the title compound has been determined by X-ray analysis. 4-(3,5-Dimethylpyrazol-l-yl)benzoic acid trifluoroacetate crystallizes in the 12/a space group witha=20.6584(13),b=9.9068(3),c=14.9467(6) , =106.195(4),V=2937.6(2) Å3, Dc=1.494 g/cm3 andZ=8. The ions pack in chains parallel to thea axis through O–HO and N–HO hydrogen bond interactions. Solid-state13C CPMASNMR spectroscopy has been used to compare the structure of the trifluoracetate with that of the neutral molecule [4-(3,5-dimethylpyrazol-l-yl)benzoic acid]. 相似文献
56.
[W3(O)O3Cl3(C5H5N)6]2W6O19·6C5H5N, the side product of the reaction between WCl4(C5H5N)2 and pyridine, crystallizes in the rhombohedral space groupR¯3 (No. 148), witha=14.044(1) Å,=87.70(1)°, andZ=1. The structure was solved by the heavy-atom method, and refined to the unweighted and weighted residuals of 0.068 and 0.055, respectively. The tungsten atoms define an equilateral triangle with a capping and three bridging oxygen atoms. Two pyridines in thecis position and a chlorine atom form, together with the oxygens, a distorted octahedron around the tungsten atoms; three octahedra are connected through common edges. Important bond lengths are: W-W (single bond) 2.532(1), W-O (tricapped) 2.09(1), W-O (bridging) 1.92(1) and 1.94(1), W-C1 2.424(5), and W-N (pyridine) 2.23(1) and 2.26(1) Å. In W6O
19
2–
, six WO6 octahedra have one common central oxygen, twelve bridging and six terminal oxygen atoms. Corresponding W-O bond lengths are: 2.323(1) (central oxygen), from 1.90 to 1.94(1) (bridging oxygens), and 1.70(2) Å (terminal oxygens). Lattice pyridine molecules have no important contacts with either anion or cation. 相似文献
57.
Abstract
In order to investigate the intramolecular [4 + 2] cycloaddition, we prepared some new tertiary N-(5-substituted-2-furfuryl)-N-prop-2-ynyl-p-toluidines [Hergold-Brundić et al., Acta Cryst C56:e520, 2000; Mance and Jakopčić, Mol Divers 9:229, 2005; Mance, “unpublished results”] by the alkylation of secondary N-(5-substituted-2-furfuryl)-p-toluidines with the propargyl-bromide [Mance and Šindler-Kulyk, Synth Commun 26:923, 1996]. In the course of preparation of N-(5-methoxy-2-furfuryl)-N-prop-2-ynyl-p-toluidine [Mance, “unpublished results”], besides the main product (compound 1) (Scheme 1) we obtained N,N-di(prop-2-ynyl)-p-toluidine (compound 2) as the colourless crystals. The title compound 2, N,N-di(prop-2-ynyl)-p-toluidine, C13H13N, crystallizes in monoclinic C 2/c space group with unit cell parameters: a = 19.5319(9) ?, b = 7.5230(3) ?, c = 15.9000(7) ?, β = 112.554(5)°, V = 2157.64(18) ?3, Z = 8. The crystal structure is dominated by van der Waals forces only. The bond distances around amine N atom correspond to σ dominated bonds (1.467(2), 1.462(2) and 1.419(2) ?). The angles sum around amine N atom is in accord with sp3 hybridization (343°). 相似文献58.
Monique Perrin Alain Thozet Sylvain Lecocq Jose Elguero Ana Martinez Alain Fruchier 《Journal of chemical crystallography》1993,23(12):961-965
The title compound (C7N2H10, HC1, 1/2H2O) crystallizes in the space groupC2/c with cell parameters:a=11.651(9),b=16.309(1),c=9.167(1)Å,=94.95(3)°,Z=8, withd=1.287 g cm–3. One of the chlorine atoms lies on a twofold axis, the second and the oxygen atom of the water molecule have disordered positions. Intermolecular interactions through hydrogen bonds are established between nitrogen atoms of the pyrazole ring and chlorine atoms or the water molecule. In this way, chains of molecules are built; these chains, through van der Waals interactions, form layers which are stacked in the a direction. The1H,13C, and15N NMR (this last using the double labelled compound) have been recorded in solution and the13C NMR spectrum also in the solid state (CP/MAS technique). The NMR parameters ( andJ's) thus obtained are discussed using the molecular structure. 相似文献
59.
Ana de Bettencourt-Dias Rose M. Beeler Sharon S. Tse 《Journal of chemical crystallography》2011,41(2):192-197
Abstract
Dipyridylamine has been coupled with phenyl groups to yield new organic ligands. During the course of one reaction a lithium salt of dipyridylamine was isolated as the product. These new compounds were characterized by single crystal X-ray diffraction, which reveals that π–π stacking interactions as well as hydrogen bonding permeate the isolated compounds in the solid state. BrPhDPA, compound 1, crystallizes in the monoclinic P21 space group with cell parameters a = 5.8291(1), b = 8.8504(2), c = 13.2341(3) ? and β = 91.928(1)°. 3-ThPh(DPA)2, compound 4, crystallizes in the orthorhombic C2/c space group with cell parameters a = 14.8033(7), b = 11.4124(4), c = 16.11780(7) ? and β = 115.911(3)°. Finally the lithium salt, [Li(HDPA)(H2O)2](H2DPA)(Cl)2(H2O), compound 5, crystallizes in the monoclinic Cmcm space group with cell parameters a = 14.043(3), b = 12.370(3) and c = 13.389(3) ?. 相似文献60.
Miguel A. Harvey María E. Díaz de Vivar Ricardo Baggio Sergio Baggio 《Journal of chemical crystallography》2011,41(11):1717-1721