Reactions of mercury(II) with 2-pyridinecarboxylic and 6-methyl-2-pyridinecarboxylic acids and corresponding esters.: Crystal structures of [Hg(C5H4NCOO)2], [HgX2(C5H4NCOOPri)], X=Br or I and [HgCl2(MeC5H3NCOOEt)]

Several mercury(II) complexes with 2-pyridinecarboxylic and 6-methyl-2-pyridinecarboxylic acids as well as with corresponding esters have been obtained and some of them structurally characterized by X-ray diffraction. [HgC5H4NCOO)(2)] consists of one-dimensional chains of octahedrally coordinated mercury atoms linked by means of the oxygen atoms of the carboxylate groups. The structure of the isomorphous complexes [HgX2(C5H4NCOOPri)], X = Br or I, consists of isolated centrosymmetric dimers with unsymmetrical mu-X bridges, where mercury atoms are in a distorted square pyramidal coordination. Complex [Hg(Cl-2(MeC2H3NCOOEt)] has a polymeric chain structure formed by loosely bound formula units through a unique non-planar bis(chloride) asymmetric Hg(mu-Cl)(2)Hg bridge. In all cases picolinate ligands behave as chelates. The crystal structures are compared with those found for the related family [HgCl2(C5H4NCOOR)], R = Me,Et, Pr-n or Pr-i. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.