Crystal and molecular structures of the N,N′-dimethyl-4,4′-bipyridylium (paraquat) salts with the chlorometallate anions CoCl42–, [CuCl2]nn– and PdCl42–

Abstract

The crystal and molecular structures of the N,N′-dimethyl-4,4′-bipyridylium (paraquat) salts of the chlorometallate anions CoCl₄^2–, [CuCl₂]_n^n–, and PdCl₄^2– have been determined by three-dimensional X-ray diffraction methods. The [CuCl₂]_n^n– anion has a chain structure analogous to that of BeCl₂. The other anions have the expected forms. The paraquat cation is planar in the CoCl₄^2– and [CuCl₂]_n^n– salts but in the PdCl₄^2– salt the planes of the N-methyl pyridyl groups are inclined at an angle of 50° to each other. The N⋯ Cl inter-ion contacts have been correlated with the charge-transfer properties of the salts.