The preparation and structural characterization of a double-helical binuclear dicobalt(II) complex of 2,2′: 6′,2″: 6″,2‴: 6‴, 2⁗-quinquepyridine; the x-ray crystal structure of acetato(O,O′)bis (2,2′: 6′,2″: 6″,2‴: 6‴, 2⁗-quinquepyridine)dicobalt(II) hexafluorophosphate tris-acetonitrile solvate

Polyhedron ◽  
1991 ◽  
Vol 10 (12) ◽  
pp. 1395-1400 ◽  
Author(s):  
Edwin C. Constable ◽  
Susan M. Elder ◽  
Paul R. Raithby ◽  
Michael D. Ward
1994 ◽  
Vol 47 (2) ◽  
pp. 391 ◽  
Author(s):  
CJ Kepert ◽  
BW Skeleton ◽  
AH White

The room-temperature single-crystal X-ray structural characterization of the title compound (tpyH2)2[Tb(OH2)8]Cl7.~2⅓H2O is recorded. Crystals are triclinic, Pī , a 17.063(5), b 16.243(3), c 7.878(3) Ǻ, α 84.78(2), β 84.39(3), γ 87.81(2)°, Z = 2 formula units; 3167 'observed' diffractometer reflections were refined by full-matrix least-squares procedures to a residual of 0.057. Notable features of interest of the compound are the 'chelation' of chloride ions by the terpyridinium cations , and the existence of a free [Tb(OH2)8]2+ cation in the presence of an abundance of chloride ions.


2010 ◽  
Vol 55 (3) ◽  
pp. 1248-1255 ◽  
Author(s):  
Patricia Lassaux ◽  
Daouda A. K. Traoré ◽  
Elodie Loisel ◽  
Adrien Favier ◽  
Jean-Denis Docquier ◽  
...  

ABSTRACTThe metallo-β-lactamase VIM-4, mainly found inPseudomonas aeruginosaorAcinetobacter baumannii, was produced inEscherichia coliand characterized by biochemical and X-ray techniques. A detailed kinetic study performed in the presence of Zn2+at concentrations ranging from 0.4 to 100 μM showed that VIM-4 exhibits a kinetic profile similar to the profiles of VIM-2 and VIM-1. However, VIM-4 is more active than VIM-1 against benzylpenicillin, cephalothin, nitrocefin, and imipenem and is less active than VIM-2 against ampicillin and meropenem. The crystal structure of the dizinc form of VIM-4 was solved at 1.9 Å. The sole difference between VIM-4 and VIM-1 is found at residue 228, which is Ser in VIM-1 and Arg in VIM-4. This substitution has a major impact on the VIM-4 catalytic efficiency compared to that of VIM-1. In contrast, the differences between VIM-2 and VIM-4 seem to be due to a different position of the flapping loop and two substitutions in loop 2. Study of the thermal stability and the activity of the holo- and apo-VIM-4 enzymes revealed that Zn2+ions have a pronounced stabilizing effect on the enzyme and are necessary for preserving the structure.


2017 ◽  
Vol 72 (2) ◽  
pp. 153-158 ◽  
Author(s):  
Sebastian Bräuchle ◽  
Hubert Huppertz

AbstractLi3Y(BO3)2 was prepared by high-temperature solid state synthesis at 900°C in a platinum crucible from lithium carbonate, boric acid, and yttrium(III) oxide. The compound crystallizes monoclinically in the space group P21/c (no. 14) (Z=4) isotypically to Li3Gd(BO3)2. The structure was refined from single-crystal X-ray diffraction data: a=8.616(3), b=6.416(3), c=10.014(2) Å, β=116.6(2)°, V=494.9(3) Å3, R1=0.0211, and wR2=0.0378 for all data. The crystal structure of Li3Y(BO3)2 consists of [Y2O14] dinuclear units, which are interconnected to each other by planar B(1)O3 groups and LiO4 tetrahedra via common edges and corners along the a axis.


2003 ◽  
Vol 58 (10) ◽  
pp. 1005-1008 ◽  
Author(s):  
Martin Niehues ◽  
Gerald Kehr ◽  
Roland Fröhlich ◽  
Gerhard Erker

The reaction of 1,3-diisopropylimidazolium chloride (3) with benzylpotassium in d5-bromobenzene generates the stable carbene 1,3-diisopropylimidazol-2-ylidene that is trapped by hafnium tetrachloride. A chloride anion is subsequently added to the Hf atom of the resulting intermediate to yield the salt [(1,3-diisopropylimidazol-2-ylidene)HfCl₅−][1,3-diisopropylimidazolium+] 6 that was characterized by an X-ray crystal structure analysis.


1994 ◽  
Vol 479 (1-2) ◽  
pp. 59-72 ◽  
Author(s):  
S.P. Tunik ◽  
A.V. Vlasov ◽  
K.V. Kogdov ◽  
G.L. Starova ◽  
A.B. Nikol'skii ◽  
...  

2007 ◽  
Vol 63 (2) ◽  
pp. 270-276 ◽  
Author(s):  
Thomas Reeswinkel ◽  
Sebastian Prinz ◽  
Karine M. Sparta ◽  
Georg Roth

The new spin ½ V4+ barium oxovanadate BaV4O9 was synthesized and studied by means of single-crystal X-ray diffraction. Its room-temperature structure is monoclinic, space group P2/c. We discuss the temperature evolution of the crystal structure and thermal expansion tensor of the material between 293 and 100 K.


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