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(β-Cyclodextrin)2·KI7·9 H2O. Spatial fitting of a polyiodide chain to a given matrix (1983)

Betzel, Christian ; Hingerty, Brian ; Noltemeyer, Mathias ; [et al.]

Springer

Journal of inclusion phenomena and macrocyclic chemistry 1 (1983), S. 181-191

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ISSN: 1573-1111

Keywords: (β-cyclodextrin)2·KI7·9H2O ; zigzag and linear polyiodide ; I2·I 3 − ·I2 ; starch-iodine model ; crystal structure

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract α-Cyclodextrin, a torus shaped molecule with a 5 Å wide central cavity, forms a number of deep green, blue and black crystals when complexed with iodine/metal iodide. In contrast, β-cyclodextrin, having a 6 Å cavity produces only one type of reddish-brown crystal, no matter what metal iodide is used. The complex (β-cyclodextrin)2 ·KI7·9H2O displays space groupP21 (pseudo-C2) with cell constantsa=19.609(5),b=24.513(7),c=15.795(6)Å, β=109.50(2)°,Z=4. The crystal structure was solved inC2 on the basis of 3022 absorption corrected CuKα (Ni-filter) X-ray intensities and refined by full matrix least squares toR=17%. This relatively highR-factor is due to many weak reflections (pseudo-C2) and considerable disorder exhibited by water and iodine. In the complex, β-cyclodextrin adopts a ‘round’ shape with O(2)...O(3) interglucose hydrogen bonds formed and all O(6) hydroxyls pointing away from the cavity. Two molecules are arranged head-to-head to produce a dimer, and dimers are stacked such that a slightly zigzagged cylinder with a 6 Å-wide cavity is formed. In the cavity described by each dimer, an I 7 − ion composed of I2·I 3 − ·I2 units is located, with I2 and I 3 − perpendicular to each other. K+ ions and 9 H2O molecules are found in interstices between the β-cyclodextrin cylinders. This zigzag polyiodide contrasts with the linear form observed in the 5 Å wide α-cyclodextrin channels. It explains differences in color of the crystals and suggests that β-cyclodextrin polyiodide is not a good model for blue starch-iodine.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00656821

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Neue Komplexe des Titans mit Bis(trimethylsilyl)amido-LigandenProfessor Kurt Dehnicke zum 60. Geburtstage gewidmet (1991)

Bai, Yüniu ; Roesky, Herbert W. ; Noltemeyer, Mathias

Weinheim : Wiley-Blackwell

Zeitschrift für anorganische Chemie 595 (1991), S. 21-26

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ISSN: 0044-2313

Keywords: Titanium complex compounds ; cyclopentadienyl titanium bis(trimethylsilyl)amido compounds ; syntheses ; crystal structure ; Chemistry ; Inorganic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Description / Table of Contents: New Complexes of Titanium with Bis(trimethylsilyl)amido LigandsThe reaction of cp′TiCl3 with LiN(SiMe3)2 · Et2O 1 yield the compounds cp′TiCl2N(SiMe3)2 (cp′ = C5H5 2, C5H4SiMe3 3, C5H3(SiMe3)2 4, C5Me5 5) and cp′TiCl[N(SiMe3)2]2 (cp′ = C5H5 6). Compound 2 was characterized by an X-ray structural analysis with space group P21/n and unit cell dimensions of a = 1 660.9(7), b = 688.6(3), c = 1 739.1(8) pm and β = 117.18(3)°.

Notes: Die Reaktion von cp′TiCl3 mit LiN(SiMe3)2 · Et2O 1 führt zu den Verbindungen cp′TiCl2N(SiMe3)2 (cp′ = C5H5 2, C5H4SiMe3 3, C5H3(SiMe3)2 4, C5Me5 5) und cp′TiCl[N(SiMe3)2]2 (cp′ = C5H5 6). Verbindung 2 wurde durch eine Einkristall Röntgenstrukturanalyse charakterisiert. 2 kristallisiert in der Raumgruppe P21/n mit a = 1 660,9(7), b = 688,6(3), c = 1 739,1(8) pm und β = 117,18(3)°.

Additional Material: 1 Ill.