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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 30 (2000), S. 727-730 
    ISSN: 1572-8854
    Keywords: zapoterin ; A,D-bis-seco limonoid ; triterpene ; casimiroa edulis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of zapoterin C26H30O8 isolated from Casimiroa edulis has been determined and the compound crystallizing in the monoclinic space group P21 with a = 7.486(1), b = 16.247(3), c = 9.736(2) Å, β = 98.77(1)°, V = 1170.3(4) Å3, and Z = 2 was confirmed as 11β-hydroxyobacunone (11β-hydroxy-14,15:21,23-diepoxy-4,4,8-trimethyl-A,D-di-homo-24-nor-4,17-dioxa-chola-1,20,22-triene-3,7,16-trione) 1. The molecule comprises a tetracyclic skeleton with homo-oxa rings A and D. In the crystal, molecules form infinite ribbons along the b axis by hydrogen bonding involving the hydroxyl group and the carbonyl group of the seven-membered lactone.
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  • 2
    ISSN: 0009-2940
    Keywords: Phosphazene metallacycles ; [N-(Diphenylphosphinoselenoyl)-P,P-diphenylphosphinoselenoic amidato-Se,Se′] chelates ; Inorganic carbon-free chelate rings ; Octahedral MSe6 core (M = Sb, Bi, and In) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The [(SePPh2)2N]- ligand 1c forms stable tris(chelates) with the SbIII, BiIII, and InIII ions. The crystal and molecular structures of the resulting compounds 3, 4, and 5 were determined by X-ray diffractometry. The coordination geometry around the metal centers can be described as a distorted octahedron. This feature and the results obtained by comparing the structures with their sulfur and oxygen analogs lead us to conclude that in both SbIII and BiIII compounds the arrangement around the metals suggests a stereochemically nonactive electron lone pair.
    Additional Material: 3 Ill.
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  • 3
    ISSN: 0044-2313
    Keywords: Stibocanes ; dithiophosphinates ; conformational analysis ; x-ray structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Konformative Trends und intermolekulare Assoziation in Dialkyldithiophosphinat-Stibocanen X(CH2CH2S)2SbS2PR2 (X = O, S; R = Me, Et)Alkylstibocanes O/S(CH2CH2S) 2SbS2PMe2/ Et2 1-4 wurden aus den entsprechenden Chlorooxa- und -thiastibocanen bzw. Natriumdialkyldithiophosphinaten in CH2Cl2 dargestellt und durch IR, EI-MS und Multikern-NMR (1H, 13C, 31P{1H}) charakterisiert. Die Kristall- und Molekülstrukturen von O(CH2CH2S) 2SbS2PMe2 1 und S(CH2CH2S) 2PMe2 3 wurden bestimmt. Die Kristallstruktur von 1 zeigt ein Dimer durch zwei Sb … S-intermolekulare Wechselwirkungen (3,960(3) Å). 3 bildet im kristallinen Zustand eine dimere Struktur durch eine sekundäre Sb … Sb-Bindung (4,067(1) Å), 1 und 3 zeigen endocyclische, transannulare Sb … O/S-Wechselwirkungen (1: 2,561(7) Å; 3: 2,972(1) Å) und exocyclische, sekundäre Sb … S-Bindungen (1: 3,454(2) Å; 3: 3,147(2) Å). Die Strukturen von 1 und 3 können als trigonal bipyramidal beschrieben werden mit zusätzlichen sekundären Kontakten über eine Ebene bzw. Kantenverbrückt. Die Konformation des Achtrings in 3 ist Wanne-Sessel, die in 1 Sessel-planar.
    Notes: The alkyl stibocanes O/S(CH2CH2S)2SbS2PMe2/ Et2 1-4 were prepared from the corresponding chloro oxa and thiastibocanes, and sodium dialkyldithiophosphinates in CH2Cl2. Compounds 1-4 were characterized by IR, EI-MS and multinuclear NMR (1H, 13C, 31P{1H}). The crystal and molecular structures of O(CH2CH2S)2SbS2PMe2 1 and S(CH2CH2S)2SbS2PMe2 3 were determined. The crystalline state of 1 has two Sb … S intermolecular interactions [3.960(3) Å] that results in a dimer. The crystalline state of 3 features a dimeric structure through an Sb … Sb secondary bonding [4.067(1) Å]. Compounds 1 and 3 display both an endocyclic, transannular Sb … O/S interaction [1, 2.561(7) Å; 3 2.972(1) Å] and an exocyclic Sb … S secondary bonding [1, 3.454(2) Å, 3, 3.147(2) Å]. The coordination geometry in 1 and 3 could be described as trigonal bipyramidal with additional secondary bonding contacts face capping or edge bridging the polyhedron. The conformation of the eight membered ring in 3 is boat-chair. Whereas in 1, the mean conformation is chair-planar.
    Additional Material: 5 Ill.
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