The Solvent Effect on Composition and Dimensionality of Mercury(II) Complexes with Picolinic Acid

Three new mercury(II) coordination compounds, {[HgCl(pic)]} (), [HgCl(pic)(picH)] (), and [HgBr(pic)(picH)] () (picH = pyridine-2-carboxylic acid, picolinic acid) were prepared by reactions of the corresponding mercury(II) halides and picolinic acid in an aqueous () or alcohol-methanol or ethanol ( and ) solutions. Two different types of coordination compounds were obtained depending on the solvent used. The crystal structures were determined by the single-crystal X-ray structural analysis. Compound is a one-dimensional (1-D) coordination polymer with mercury(II) ions bridged by chelating and bridging ,,'-picolinate ions. Each mercury(II) ion is four-coordinated with a bidentate picolinate ion, a carboxylate O atom from the symmetry-related picolinate ion and with a chloride ion; the resulting coordination environment can be described as a highly distorted tetrahedron. Compounds and are isostructural mononuclear coordination compounds, each mercury(II) ion being coordinated with the respective halide ion, ,-bidentate picolinate ion, and ,-bidentate picolinic acid in a highly distorted square-pyramidal coordination environment. Compounds were characterized by IR spectroscopy, PXRD, and thermal methods (TGA/DSC) in the solid state and by H and C NMR spectroscopy in the DMSO solution.