CRYSTAL AND MOLECULAR-STRUCTURE OF 1-ALPHA,9-BETA-DICHLORO-2,2,10,10-TETRAMETHOXY-[2,2](2,6)PYRIDINOPHANE

Crystals of the title compound, C18H20CI2N2O4, are monoclinic, a 14·706(1), b 17·168(1), c 7·269(1) Å, β92·72(l)°, space group P21/c with Z = 4. The structure was solved from diffractometer data by direct methods. Block-diagonal least-squares refinement converged at R 0·037, Rw 0·045 for 2103 reflections with I ≽ 3σ(I) which had been corrected for absorption (μ 34·0 cm-1). The asymmetric unit is comprised of two independent half-molecules, each molecule being centrosymmetric. The pyridine rings are distorted from planarity, with a maximum deviation of 0·10Å at the nitrogen atoms, as a consequence of the short intramolecular N ⋯ N contacts of 2·476(4) and 2·473(5) Å. © 1978 Australian Journal of Chemistry, All rights reserved.