title: Orientational disorder in 4-chloronitrobenzene.
abstract: The crystal structure of 4-chloronitrobenzene, C(6)H(4)ClNO(2), a material that exhibits disorder in the solid state, is re-examined using multiple-temperature single-crystal X-ray diffraction. Our results show a marked improvement on previous crystal structure determinations and our comprehensive multiple temperature measurements help to rationalize the structural anomalies. 4-Chloronitrobenzene exhibits twofold orientational disorder of the NO(2)/Cl substituents, with the molecule lying across an inversion centre. There is also evidence of large thermal motion, which exists at all temperatures and reflects the presence of significant disorder in this material. The nitro group shows possible libration, with one O atom exhibiting larger thermal motion than the other across the whole temperature range. This is explained by a difference in hydrogen-bonding environment.
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, England.
authors.forename: Lynne H
authors.initials: LH
authors.lastname: Thomas
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Cole
authors.forename: Chick C
authors.initials: CC
authors.lastname: Wilson