Conformational studies. Part I. Crystal and molecular structures of cis-1,2-di-p-chlorobenzoyl- and cis-1,2-dibenzoyl-ethylene

Abstract

The crystal structures of the two named compounds have been solved from partial three-dimensional photographic data and both refined by a full-matrix least-squares programme to R′ 0·02 and R 0·07. The estimated standard deviations of bond lengths and angles are of the order of 0·02 Å and 1·0°. The molecular structures of the two compounds compare well and permit correlation between molecular conformation in which the benzoyl groups are respectively near-coplanar with and near-orthogonal to the ethylene system. The intramolecular CO ⋯ CO distance of 2·7 Å suggests interaction of these polar groups; similar, longer intermolecular contacts and C–H ⋯ OC contacts are regarded as determining the molecular packing arrangements.