THE MOLECULAR-STRUCTURE OF META-DICHLOROBENZENE, DETERMINED BY THE COMBINED ANALYSIS OF ELECTRON-DIFFRACTION, ROTATION CONSTANT AND LIQUID-CRYSTAL NUCLEAR-MAGNETIC-RESONANCE DATA

We have determined the molecular structure of meta-dichlorobenzene from new electron diffraction data and existing microwave data in the gas phase and direct dipolar couplings between spin - 1 2 nuclei in the NMR spectrum of a sample dissolved in a nematic liquid crystal solvent. The data, when corrected to a common basis (rα0), are compatible with a single structure in which the ring geometry is distorted by the chlorine substituents so that CC bonds adjacent to Cl are shorter than the others, and the CCC bond angles at the substituted carbon atoms are larger than 120°. The refined structural parameters are rC1C2 138.81(39), rC3C4 139.16(33), rC4C5 140.38(29), rCCl 173.55(14), rC2H 109.10(64), rC4H 108.46(23), rC5H 109.14(66) pm; ∠C1C2C3 118.09(38), ∠C2C3C4 122.27(18), ∠C3C4C5 118.13(23), ∠C4C5C6 121.10(40), ∠C2C3Cl 118.91(27), ∠C3C4H 121.19(22) degrees. © 1990.