Control of stereochemistry in potassium alkoxide accelerated [1,3] sigmatropic rearrangements by the use of a crown ether for the apparent destruction of ion pairs. Evidence for a fragmentation mechanism in a vinylcyclobutane rearrangement

1983 ◽  
Vol 105 (23) ◽  
pp. 6978-6979 ◽  
Author(s):  
M. Bhupathy ◽  
Theodore Cohen
Keyword(s):  
Crown Ether ◽  
Ion Pairs ◽  
Fragmentation Mechanism ◽  
Sigmatropic Rearrangements

Formation of ion pairs in rubidium-tetrahydrofuran crown ether solutions

1980 ◽  
Vol 84 (8) ◽  
pp. 842-847 ◽  
Author(s):  
U. Eliav ◽  
Haim Levanon
Keyword(s):  
Crown Ether ◽  
Ion Pairs

Synthesen und Kristallstrukturen der Kronenether-Komplexe (18-Krone-6) · 2CH3CN, [Na-15-Krone-5][ReO4] · CH3CN und [Na-15-Krone-5]PF6 / Syntheses and Crystal Structures of the Crown Ether Complexes (18-Crown-6) · 2 CH3CN, [Na-15-Crown-5][ReO4] · CH3CN, and [Na-15-Crown-5]PF6

1989 ◽  
Vol 44 (12) ◽  
pp. 1524-1530 ◽  
Author(s):  
Frank Weller ◽  
Harald Borgholte ◽  
Harald Stenger ◽  
Stefan Vogler ◽  
Kurt Dehnicke
Keyword(s):  
Crown Ether ◽  
Sodium Fluoride ◽  
Ion Pairs ◽  
Sodium Atom ◽  
Acetonitrile Solution ◽  
Space Group ◽  
Crown Ether Complexes ◽  
Water Space ◽  
Ether Molecule ◽  
Oxygen Atoms

Single crystals of (18-crown-6) · 2 CH3CN were obtained by cooling a solution of 18-crown-6 in acetonitrile to 4 °C. Space group P21/n, Z = 2, 629 observed independent reflexions, R = 0.062. Lattice dimensions at 19°C: a = 911.7(1), b = 852.0(1), c = 1370.0(2) pm; β = 104.61(1)°. The compound forms a molecular structure with approximate D3d symmetry of the crown ether molecule, and C—H ··· O interactions of the acetonitrile molecules with the crown ether, the Η···Ο distances being 243, 253, and 267 pm, respectively.[Na-15-crown-5][ReO4] · CH3CN is formed as a by-product of the reaction of ReNCl4 with sodium fluoride in acetonitrile in the presence of 15-crown-5 and traces of water. Space group Ρ 1̄ , Ζ = 2, 3107 observed independent reflexions, R = 0.045. Lattice dimensions at 19°C: a = 823.4(1), b = 1078.8(1), c = 1204.0(1) pm; α = 112.40(1)°, β = 94.35(1)°, γ = 104.63(1)°. The compound forms ion pairs, in which the sodium atom is sixfold coordinated by the five oxygen atoms of the crown ether molecule, as well as by one oxygen atom of the ReO4- ion, which is only slightly distorted. The bond length Na—OReO3 is 237.8(8) pm, the bond angle NaORe is 164.3(5)°.[Na-15-crown-5]PF6 is formed in the reaction of [ReCl3(NSCl)2 · POC13] with sodium fluoride in acetonitrile solution in the presence of 15-crown-5. Space group Pna21, Ζ = 4, 1130 observed independent reflexions, R = 0.123. The high R value is due to disorder of the skeletal atoms of the crown ether molecule. The compound forms ion pairs, in which the sodium atom is sevenfold coordinated by the five oxygen atoms of the crown ether molecule, as well as by two fluorine atoms of the PF6- ion with Na—F bond lengths of 240(2), and 246(2) pm, respectively.

Synthese und Kristallstruktur von [Na-15-Krone-5][MoF5 (NCl)]

1988 ◽  
Vol 43 (9) ◽  
pp. 1125-1129 ◽  
Author(s):  
Dieter Fenske ◽  
Karin Völp ◽  
Kurt Dehnicke
Keyword(s):  
Crown Ether ◽  
Nmr Spectra ◽  
Bond Angle ◽  
Ion Pairs ◽  
Sodium Ion ◽  
Acetonitrile Solution ◽  
Crystal Data ◽  
X Ray ◽  
Data Space ◽  
Ether Molecule

Abstract [Na-15-Crown-5][MoF5(NCl)] has been prepared as yellow crystals by the reaction of NaF with MoF4(NCl) in the presence of 15-crown-5 in acetonitrile solution. The compound was charac­terized by its IR and 19F NMR spectra as well as by an X-ray structure determination. Crystal data: space group P21/n, Z = 4 (3736 observed, independent reflexions, R = 0.034). Lattice dimensions at -70 °C: a = 823.5(4). b = 1612.2(9), c = 1383.4(8), β = 99.35(3)°. The compound forms ion pairs, in which the sodium ion is seven-coordinated by the oxygen atoms of the crown ether molecule and by two fluorine ligands of the [MoF5(NCl)]- unit with Na-F distances of 228.3 and 249.6 pm. The Mo=N-Cl group of the anion is nearly linear (bond angle 175.8°) with bond lengths MoN = 172.9 and NCl = 161.8 pm.

scholarly journals Polysulfonylamine, XLIV Synthese von [Na(15-Krone-5)][N(SO2CH3)2] und Kristallstruktur bei –95°C / Polysulfonylamines, XLIV Synthesis of [Na(15-Crown-5)][N(SO2CH3)2] and Crystal Structure at –95°C

1993 ◽  
Vol 48 (7) ◽  
pp. 893-897 ◽  
Author(s):  
Armand Blaschette ◽  
Karl-Heinz Nagel ◽  
Peter G. Jones
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crown Ether ◽  
Ion Pairs ◽  
Sodium Cation ◽  
Methanol Solution ◽  
Sodium Ion ◽  
Monoclinic Space Group ◽  
Ether Oxygen ◽  
Oxygen Atoms

The complex [Na(15-crown-5)][N(SO2CH3)2] crystallizes at —25°C from a methanol solution containing equimolar amounts of NaN(SO2CH3)2 and 15-crown-S. Its crystallographic data at —95°C are: monoclinic, space group P 21/c, a = 852.1(5), b = 2731.9(12), c = 909.2(4) pm, β = 115.53(4)°, V = 1.910 nm3, Z = 4, Dx = 1.445 Mgm3. The structure in the solid state consists of ion pairs. The sodium cation is coordinated to the five oxygen atoms of the crown ether, one oxygen atom of the anion, and to the nitrogen atom of the anion. The bond distances are Na—O(crown) 238.7-247.2, Na—O(sulfonyl) 234.9, Na—N 275.8 pm. The sodium ion lies 78 pm out of the plane of the crown ether oxygen atoms. The conformation of the coronand is described.

[Na-15-Krone-5] [ReF2Cl2(NO)2]; Synthese, IR-Spektrum und Kristallstruktur / [Na-15-Crown-5][ReF2Cl2(NO)2]; Synthesis, IR Spectrum, and Crystal Structure

1989 ◽  
Vol 44 (11) ◽  
pp. 1393-1396 ◽  
Author(s):  
Stefan Vogler ◽  
Kurt Dehnicke ◽  
Dieter Fenske
Keyword(s):  
Crystal Structure ◽  
Ir Spectroscopy ◽  
Crown Ether ◽  
Ir Spectrum ◽  
Ion Pairs ◽  
Sodium Ion ◽  
X Ray ◽  
Moisture Sensitive ◽  
In Cis ◽  
Ether Molecule

[Na-15-crown-5][ReF2Cl2(NO)2] has been prepared by the reaction of ReCl3(NO)2 with sodium fluoride in acetonitrile suspension in the presence of 15-crown-5. It forms green, slightly moisture sensitive crystals, which were characterized by IR spectroscopy as well as by an X-ray structure determination. Space group P21/c, Z = 4, 4821 observed unique reflexions, R = 0.040. Lattice dimensions at —60 °C: a = 1024.6(7), b = 801.4(4), c = 2386.6(12) pm; β = 99.90(4)°. The compound forms ion pairs via two Na—F contacts with bond lengths of 239.8 and 233.4 pm. Thus the sodium ion is seven-coordinate by the five oxygen atoms of the crown ether molecule and by two fluorine ligands of the [ReF2Cl2(NO)2]- unit. The nitrosyl groups of the anion are in transposition to the fluorine atoms and in cis-position to one another (symmetry C2v).

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