Modification of the reactivity of polyhydrides with Lewis acids. Synthesis and reactivity of {IrH5[P(iso-C3H7)3]2}2Cu(CF3SO3). X-ray crystal structure of {IrH2(MeCN)2[P(iso-C3H7)3]2}(BF4)

1990 ◽  
Vol 29 (24) ◽  
pp. 5000-5002 ◽  
Author(s):  
X. D. He ◽  
J. Fernandez-Baeza ◽  
B. Chaudret ◽  
K. Folting ◽  
K. G. Caulton
Keyword(s):  
2000 ◽  
Vol 55 (1) ◽  
pp. 60-64
Author(s):  
Melanie Pülm ◽  
Joachim Becht ◽  
Reinhold Tacke

The zwitterionic λ5Si-tetrafluorosilicates F4SiCH2NMe2H (1) and F4SiCH2NMe3 (2) behave as Lewis acids and react with [Me3NH]F (molar ratio 1:1) in aqueous solution to yield the ionic λ6Si-pentafluorosilicates [Me3NH][F5SiCH2NMe2H] (3) and [Me3NH][F5SiCH2NMe3] (4), respectively. These hexacoordinate silicon compounds contain singly charged λ6Si-silicate anions ([F5SiCH2NMe2H]- , [F5SiCH2NMe3]- ) with an SiF5C skeleton. Compounds 3 and 4 were isolated as the crystalline hydrates 3·H2O (yield 80%) and 4·H2O (yield 82%) which were structurally characterized by single-crystal X-ray diffraction. The Si-coordination polyhedra in the crystals of 3·H2O and 4·H2O are slightly distorted octahedra


1991 ◽  
Vol 46 (12) ◽  
pp. 1706-1712 ◽  
Author(s):  
Norbert Kuhn ◽  
Gerald Henkel ◽  
Jörg Kreutzberg

1,2,4,5-Tetramethylimidazole (3) is obtained by metalation of 2,4,5-trimethylimidazole (2) with sodium in liquid ammonia and subsequent addition of methyl iodide. 3 reacts with Lewis acids to form the compounds Me4C3N2 · BH3 (8) and Me4C3N2 · E+ (4, 5, 7, 10; E = Me, H, SiMe3, C(O)Me). The X-ray structure reveals the ionic nature of pentamethylimidazolium iodide (4) in the solid state.


2003 ◽  
Vol 58 (2-3) ◽  
pp. 217-225 ◽  
Author(s):  
Joachim Nikolai ◽  
Gerhard Taubmann ◽  
Gerhard Maas

Adducts of various acyclic enaminoketones and enaminoaldehydes with the Lewis acids boron trifluoride and triphenylboron were prepared. The adducts were characterized by NMR (1H, 13C, 11B) and IR spectroscopy, FAB-MS, and X-ray crystal structure analysis of the adducts of (E)-3- diethylamino-3-phenyl-2-propenal with BF3 (4a) and BPh3 (5a), respectively. The adduct formation occurs at the oxygen atom of the enaminocarbonyl compound and gives rise to a betainic structure with expressed equalization of the bond orders in the enaminocarbonyl moiety. The gas-phase structures of complexes 4a and 5a and of the corresponding free enaminoaldehyde were determined computationally by RHF and DFT methods, and a Natural Bond Orbital (NBO) analysis was undertaken.


Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.


Planta Medica ◽  
2008 ◽  
Vol 74 (03) ◽  
Author(s):  
W Gul ◽  
P Carvalho ◽  
D Slade ◽  
M Avery ◽  
JR Duchek ◽  
...  
Keyword(s):  

Author(s):  
Süheyla Özbey ◽  
F. B. Kaynak ◽  
M. Toğrul ◽  
N. Demirel ◽  
H. Hoşgören

AbstractA new type of inclusion complex, S(–)-1 phenyl ethyl ammonium percholorate complex of R-(–)-2-ethyl - N - benzyl - 4, 7, 10, 13 - tetraoxa -1- azacyclopentadecane, has been prepared and studied by NMR, IR and single crystal X-ray diffraction techniques. The compound crystallizes in space group


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