Crystal and molecular structure of anti-3′,4′-difluoro-2-hydroxyiminopropiophenone

Abstract

The two isomers of 3′,4′-difluoro-2-hydroxyiminopropiophenone show different biological activities. Crystals of the more active form are monoclinic, space-group Cc, with a= 3·848, b= 20·695, c= 11·585 Å, β= 103·83°, and Z= 4. The structure was determined from visually estimated Weissenberg data by a direct phase-determining method, and refined to R 0·075 for 748 reflexions. The analysis shows this isomer to be the anti-form and confirms the trans-oid arrangement of the carbonyl and hydroxyimino-groups. The molecule may be described by the three planes defined by the difluorophenyl, carbonyl, and hydroxyimino-groups, which are twisted with respect to each other. The structure contains intermolecular O–H⋯O bonds of 2·70 Å.