Solid phase carbon-13 NMR studies of dicyclohexyl-18-crown-6 ethers and some alkali metal phenoxide complexes

✍ Scribed by G.W Buchanan; J.A Ripmeester; J.W Bovenkamp; A Rodrigue

• Book ID: 104218578
• Publisher: Elsevier Science
• Year: 1986
• Tongue: French
• Weight: 227 KB
• Volume: 27
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)84496-2

✦ Synopsis

From C-13 CPMAS spectra, the asymmetric units in the crystalline state of a number of title species have been determined. Results are compared with available x-ray data and liquid phase C-13 spectra. Recently the details of the dynamic stereochemistry of the cis-syn-cis and cis-anti-cis isomers of dicyclohexano-18-crown-6 ethers and their sodium and potassium phenoxide complexes in solution have been elucidated (1,Z). In all cases rapid conformational averaging at room temperature leads to the observation of only five C-13 signals for the macrocyclic ligand and four C-13 signals for the phenoxide moiety. With the present interest in the conformational properties of "host-guest" complexes in the solid state, the application of high resolution C-13 CPMAS techniques to this area seems appropriate. For the cis-anti-cis isomer (1) below, the x-ray structure (3) of the B' polymorph (4) has been reported. The crystal is found to possess a centre of symmetry.