Crystal and molecular structure of salicylaldehyde azine
- 1 January 1969
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society B: Physical Organic
- p. 733-741
- https://doi.org/10.1039/j29690000733
Abstract
The crystal and molecular structure of salicylaldehyde azine has been determined by Patterson and Fourier methods from three-dimensional X-ray data, and refined by anisotropic least-squares methods to a final R value of 0·087. The crystals are monoclinic, space group P21/c, with two molecules in the unit cell of dimensions a= 8·467, b= 6·318, c= 12·432 Å, β= 112°22′. The molecules are centrosymmetric and nearly planar; the small deviations from planarity are indicative of intramolecular overcrowding between the two ortho-substituents in the benzene ring. The distribution of bond distances within the benzene ring is consistent with a significant contribution to the structure from a resonance quinonoid form. A strong internal hydrogen bond of 2·645 Å binds the phenolic hydroxy-group to the nearest nitrogen atom in the azine chain. The molecules are packed in plane-to-plane stacks within the crystal, with a perpendicular spacing between adjacent molecules of about 3·4 Å, which in part accounts for its thermochromic properties.Keywords
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