The crystal structure of 2,5-dichloroaniline, C6H3CleNH 2, has been determined by the combined application of nuclear quadrupole resonance and X-ray diffraction.The molecule is planar, except for the nitrogen which deviates slightly, by 0.06 A. The benzene ring is slightly deformed from the regular hexagon and the observed bond lengths agree well with the result of a simple molecular orbital calculation. There is no hydrogen bonding in the structure. The shortest intermolecular C1...C1 distance, 3.37 A, is shorter than the usually quoted van der Waals distance of 3.6 A.

The crystal structures of monoclinic quinhydrone C6H402. C6H4(OH)2 (space group is P21/c with a=7.647, b=6.001, c=11.590A and fl=109°58 ') and phenoquinone C6H402.2(C6HsOH) (space group is P21/c with a= 11.152, b= 5.970, c= 11-499 ~ and fl= 100°0 ') were refined from three-dimensional X-ray diffraction data. Different molecules in each complex are connected by hydrogen bonds between the hydroxyl and the carbonyl group. In quinhydrone, an infinite molecular chain is formed by the hydrogen bonds, while in phenoquinone one quinone molecule is placed between two phenol molecules to form a short complex chain. In spite of this difference between the complex chains, no essential difference was observed between the complexes as regards the short interatomic distances. A significant difference of the C-C-OH bond angles between hydrogen side and the non-hydrogen side was observed.

No abstract

No abstract

The structure of the title compound, C44H28N4CoCl, has been determined by single-crystal X-ray diffraction. The crystals are body-centered tetragonal, with a=b=13.693(2), c=9.701(2) Å, and Z=2. The space group was determined to be I4 from the measurement of the anomalous dispersion effect. The structure was predicted prior to the X-ray analysis from the calculation of the intermolecular van der Waals energy; the result agreed quite well with the experimentally determined structure. A tetragonal pyramidal five coordination with the chlorine atom at the apex was found for the cobalt atom. The cobalt-chlorine distance is 2.149 (6) Å, about 0.1 Å shorter than those found in ordinary octahedral coordinations.