Syntheses, structures, and magnetic and optical properties of the compounds [Hg3Te2][UCl6] and [Hg4As2][UCl6]

Two new quaternary salts, [Hg3Te2][UCl6] and [Hg4As2][UCl6], have been synthesized and their structures determined by single-crystal X-ray diffraction analysis. [Hg3Te2][UCl6] is the product of a reaction involving UCl4, HgCl2, and HgTe at 873 K. The compound crystallizes in space group P21/c of the monoclinic system. [Hg4As2][UCl6] results from the reaction of U, Hg2Cl2, and As at 788 K. It crystallizes in space group Pbca of the orthorhombic system. [Hg3Te2][UCl6] has a two-dimensional framework of image layers, whereas [Hg4As2][UCl6] has a three-dimensional framework of image layers interconnected by Hg atoms linearly bonded to As atoms. Both framework structures contain discrete [UCl6]2− anions between the layers. [Hg3Te2][UCl6] exhibits temperature-independent paramagnetism. The optical absorption spectra of these compounds display f–f transitions.