Three-co-ordinate mercury: crystal structure and spectroscopic properties of trimethylsulphonium trichloromercurate(II)

Abstract

The structure of the title compound has been solved from diffractometer data by the heavy-atom method and refined by least-squares techniques to R 8.24% for 890 independent reflections. Crystals are monoclinic, space group P2₁/n, with unit-cell dimensions: a= 8.894(6), b= 14.603(8), c= 7.476(6)Å, β= 97.85(5)°, Z= 4. The structure consists of planar trigonal [HgCl₃]^– anions and pyramidal [Me₃S]⁺ cations. Two chloride ions bridge consecutive [HgCl₃]^– anions, giving rise to infinite chains running along [001]. I.r. and Raman spectra between 3 500 and 50 cm^–1 have been recorded and characteristic [Me₃S]⁺ and [HgCl₃]^– frequencies assigned. The spectral features agree with the planar trigonal structure of the anion. Raman data and molecular-weight measure-ments showed that [HgCl₃]^– is strongly dissociated in aqueous solution.