Stereochemistry of oxygenated 10-membered rings: X-ray crystal structure, theoretical calculations and H-1 and C-13 NMR studies of benzo-10-crown-3 ether in solution and in the solid phase

The title molecule crystallizes in space group P21/c, with a = 7.2705(20), b = 10.825(3), c = 12.790(5) Angstrom,beta = 93.51(3)degrees and Z = 4. The solid phase C-13 NMR spectrum is discussed in relation to that obtained in solution. A dideuterio derivative has been synthesized to aid in the spectral assignments. Conformational preferences of the 10-membered ring in the solid state are compared with results of molecular mechanics calculations using MM2 and quantum mechanical methods employing the AM1 approach. (C) 1997 Elsevier Science B.V.