SOLID-STATE AND SOLUTION STEREOCHEMISTRY OF CROWN-ETHERS AND MODELS - ORTHO-DIMETHOXYDIPHENYL ETHER AND RELATED DIBENZO-15-CROWN-5 AND TETRABENZO-30-CROWN-10 ETHERS AS STUDIED BY X-RAY CRYSTALLOGRAPHY AND H-1 AND C-13 NMR SPECTROSCOPY

Solid phase 45.3 MHz C-13 NMR spectra of ortho-dimethoxydiphenyl ether, 1, dibenzo[b,e]-15-crown-5-ether, 2, and tetrabenzo[b,e,q,t]-30-crown-10 ether, 3, have been obtained. Chemical shift trends are discussed in terms of the asymmetric units and structural features available from X-ray crystallographic data. Comparison with solution C-13 spectra are made. The crystal structures of 1 and 3 were determined by X-ray diffraction at room temperature. 1 crystallizes in space group P2(1)/a with a = 13.366(1), b = 8.230(1), c = 12.303(1) Angstrom, beta = 116.63(1)degrees, Z = 4. 3 crystallizes in space group P2(1)/c with a = 7.903(1), b = 26.337(2), c = 7.852(1) Angstrom, beta = 97.28(1)degrees, Z = 2. The structures were solved by direct methods and refined by full-matrix least squares to residuals of 0.055 using 1727 reflections for 1 and of 0.042 using 2590 reflections for 3.