Reference of 33100-27-5. Chemistry is an experimental science, and the best way to enjoy it and learn about it is performing experiments.Introducing a new discovery about 33100-27-5, Name is 1,4,7,10,13-Pentaoxacyclopentadecane
STRUCTURES OF 18-CROWN-6, 15-CROWN-5 AND THEIR METAL COMPLEXES IN METHANOL SOLUTION AS STUDIED BY RAMAN SPECTROSCOPY
Raman spectra of 18-crown-6, 15-crown-5, and their complexes with Li+, Na+, K+, Cs+, Mg2+, Ca2+ and Ba2+ have been investigated in methanol solution.Normal coordinate calculations are presented for the D3d- and Ci-symmetric structures of 18-crown-6.Analysis of the Raman spectra gives information on the ring conformations of the crown ethers and the stoichiometry of complexation.The uncomplexed ethers adopt diverse conformational states in methanol at room temperature, the D3d state being the most stable in 18-crown-6 and various states equally stable in 15-crown-5.Most of the cation form 1:1 or 2:1 crown-metal complexes depending on the cation size relative to the hole size of crown.Exceptionally, Cs+ forms both 1:1 and 2:1 complexes with 18-crown-6.The ring structures in complexes of 18-crown-6 are not much distorted from the D3d one, though the distortion is rather large in the 2:1 Cs+ and 1:1 Ca2+ complexes.Complexes of 15-crown-5 exhibit four types of ring structure depending on the size and charge of the cation.These structures are likely to involve distortion from the gauche or gauche’ conformation about the C-C bonds and various conformations about the C-O bonds.
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Chiral Catalysts,
Chiral catalysts – SlideShare