scholarly journals Novel O-C-C-O and C-O-C-C stereochemistry in crown ether analogs. X-ray crystal structure and NMR studies of dibenzo-20-crown-6

1995 ◽  
Vol 73 (1) ◽  
pp. 100-105 ◽  
Author(s):  
G.W. Buchanan ◽  
A. Moghimi ◽  
C. Bensimon
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crown Ether ◽  
Crown Ethers ◽  
Nmr Studies ◽  
Trans Conformation ◽  
Torsion Angles ◽  
X Ray ◽  
Solid State Conformation ◽  
C Nmr

The X-ray crystal structure of the title material indicates that the molecule possesses a pseudo-centre of inversion. A pair of O-C-C-O bonds have a trans conformation in contrast to normal gauche stereochemistry for such units in crown ethers. For the C-O-C-C networks, which are normally transoid in crown ethers, all four such units involving methylene carbons of the 20-membered ring exhibit unusual geometries. Two units possess gauche conformations and the other two have torsion angles near 120°. Solution 1H and 13C NMR spectra have been recorded as a function of temperature and 13C solid state spectra are included. Keywords: crown ether, solid state conformation.

Solid state stereochemistry of crown ethers: X-ray crystal structure and 13C NMR studies of the LiNCS complex of 1,4,7,11-tetraoxacyclotetradecane

2000 ◽  
Vol 78 (3) ◽  
pp. 316-321
Author(s):  
G W Buchanan ◽  
A B Driega ◽  
G PA Yap
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crown Ether ◽  
13C Nmr ◽  
Title Complex ◽  
Nmr Studies ◽  
Nmr Spectrum ◽  
X Ray ◽  
Large Amplitude Motion ◽  
C Nmr

The title complex is asymmetric in the crystal due to the spatial orientation of the NCS function. The space group has been determined to be P21 with a = 9.496(3), b = 8.736(3), c = 9.676(3) Å, β = 117.859(5)°, and Z = 2. The solid state 13C NMR spectrum is consistent with the lack of symmetry in the crystal and there is little evidence for large amplitude motion in the macrocycle as determined from the dipolar dephased spectrum.Key words: macrocyclic crown ether, lithium complex.

Synthesis, X-ray crystal structure, and solid-state 13C NMR study of tris(9-crown-3)triphenylene

2001 ◽  
Vol 79 (2) ◽  
pp. 195-200 ◽  
Author(s):  
Gerald W Buchanan ◽  
Majid F Rastegar ◽  
Glenn PA Yap
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crown Ether ◽  
Chemical Shifts ◽  
Aromatic Rings ◽  
X Ray ◽  
Nmr Study ◽  
Group A ◽  
C Nmr ◽  
Solid State 13C Nmr

Benzo-9-crown-3 ether trimerizes in the presence of FeCl3 and aqueous H2SO4 to produce tris(9-crown-3)triphenylene in 25.4% yield. This compound crystallizes in the monoclinic P21/c space group: a = 13.759(2) Å, b = 13.318(2) Å, c = 13.399(2) Å, β = 96.883(2)°, with Z = 4. The three 9-crown-3 ether units of the trimer possess different geometries and there is substantial deviation from coplanarity in the three aromatic rings. 13C NMR chemical shifts in the solid state are consistent with this lack of symmetry and are discussed in terms of the X-ray crystal-structure data.Key words: crown ether, trimerization, stereochemistry.

scholarly journals Structural Investigations of C-Nitrosobenzenes. Part 3.1 Solid-state and Solution 13C NMR Studies, and Crystal Structure of E-(4-CIC6H4NO)2

1999 ◽  
Vol 23 (3) ◽  
pp. 202-203
Author(s):  
Daniel A. Fletcher ◽  
Brian G. Gowenlock ◽  
Keith G. Orrell ◽  
David C. Apperley ◽  
Michael B. Hursthouse ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
13C Nmr ◽  
Nmr Studies ◽  
Structural Investigations ◽  
Nmr Data ◽  
C Nmr

Solid-state and solution 13C NMR data for the monomers and dimers of 3- and 4-substituted nitrosobenzenes, and the crystal structure of E-(4-CIC6H4NO)2 are reported.

3-Hexyne Complexes of M olybdenum(II) and Tungsten(II) Containing 2, 2 '-Bipyridine. X-Ray Crystal Structure of [MoI2(CO)(bipy)(η2-EtC2Et)]

2000 ◽  
Vol 55 (11) ◽  
pp. 1095-1098
Author(s):  
Mutlaq Al-Jahdali ◽  
Paul K. Baker ◽  
Michael B. Hursthouse ◽  
Simon J. Coles
Keyword(s):  
Crystal Structure ◽  
Carbon Monoxide ◽  
Room Temperature ◽  
Octahedral Geometry ◽  
Cationic Complex ◽  
Molybdenum Complex ◽  
Neutral Complex ◽  
Nmr Studies ◽  
X Ray ◽  
C Nmr

Reaction of [MI2(CO)(NCMe)(η2-EtC2Et)2] (M = Mo,W) with one equivalent of 2,2' -bipyridine (bipy) in CH2C12 at room temperature gives either the neutral complex, [MoI2(CO)(bipy)- (η2-EtC2Et)] (1) or the cationic complex, [WI(CO)(bipy)(η2-EtC2Et)2]I (2). The neutral molybdenum complex 1, has been crystallographically characterised, and has a pseudo-octahedral geometry with the iodo-ligand trans to the 3-hexyne, and with the bipy, carbon monoxide and other iodo-ligand occupying the equatorial face. 13C NMR studies show the 3-hexyne is donating four electrons to the molybdenum in 1.

ChemInform Abstract: Synthesis, X-Ray Crystal Structure Analyses, and Solid-State NMR Studies of Some Zwitterionic Organofluorosilicates.

ChemInform ◽  
2010 ◽  
Vol 24 (41) ◽  
pp. no-no
Author(s):  
R. TACKE ◽  
J. BECHT ◽  
A. LOPEZ-MRAS ◽  
W. S. SHELDRICK ◽  
A. SEBALD
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Solid State Nmr ◽  
Nmr Studies ◽  
X Ray

On the solid state conformation of azithromycin monohydrate and dihydrate pseudopolymorphs

2005 ◽  
Vol 220 (1) ◽  
Author(s):  
José Manuel Montejo-Bernardo ◽  
Santiago Garcia-Granda ◽  
Miguel Santos Bayod-Jasanada ◽  
Lujan Llavona-Díaz ◽  
Isidro Llorente
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Single Crystal ◽  
Chemical Compound ◽  
X Ray ◽  
Crystal State ◽  
Crystalline Forms ◽  
Solid State Conformation

AbstractThis paper describes the crystal structure of the azithromycin monohydrate pseudopolymorph (pseudopolymorphic forms, different solvates of the same chemical compound, azithromycin in our case) crystallised from isopropanol, solved by X-ray single crystal, and calledComparing the monohydrate and the dihydrate crystalline forms, we try to explain the role played by the solvent in the final results, and find a relation between the conformation in solution and in the crystal state conformation for the antibiotic.The crystal obtained using

Sign in / Sign up

Export Citation Format

Share Document