Isotypic one-dimensional coordination polymers: catena-poly[[di-chlorido-cadmium]-μ-5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ato-κ(2) N (5):N (6)] and catena-poly[[di-chlorido-mercury(II)]-μ-5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ato-κ(2) N (5):N (6)]

Montserrat Alfonso; Helen Stoeckli-Evans

doi:10.1107/S2056989016012093

Isotypic one-dimensional coordination polymers: catena-poly[[di-chlorido-cadmium]-μ-5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ato-κ(2) N (5):N (6)] and catena-poly[[di-chlorido-mercury(II)]-μ-5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ato-κ(2) N (5):N (6)]

Acta Crystallogr E Crystallogr Commun. 2016 Jul 29;72(Pt 8):1214-8. doi: 10.1107/S2056989016012093. eCollection 2016 Aug 1.

Authors

Montserrat Alfonso¹, Helen Stoeckli-Evans²

Affiliations

¹ Institute of Chemistry, University of Neuchâtel, Av. de Bellevaux 51, CH-2000 Neuchâtel, Switzerland.
² Insitute of Physics, University of Neuchâtel, rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland.

Abstract

The isotypic title one-dimensional coordination polymers, [CdCl2(C18H14N4O4)] n , (I), and [HgCl2(C18H14N4O4)] n , (II), are, respectively, the cadmium(II) and mercury(II) complexes of the dimethyl ester of 5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carb-oxy-lic acid. In both compounds, the metal ions are located on a twofold rotation axis and a second such axis bis-ects the Car-Car bonds of the pyrazine ring. The metal ions are bridged by binding to the N atoms of the two pyridine rings and have an MN2Cl2 bisphenoidal coordination geometry. The metal-Npyrazine distances are much longer than the metal-Npyridine distances; the difference is 0.389 (2) Å for the Cd-N bonds but only 0.286 (5) Å for the Hg-N bond lengths. In the crystals of both compounds, the polymer chains are linked via pairs of C-H⋯Cl hydrogen bonds, forming corrugated slabs parallel to the ac plane.

Keywords: C—H⋯Cl hydrogen bonding; MN2Cl2 bisphenoidal coordination geometry; crystal structure; dimethyl ester; isotypic coordination polymer; one-dimensional; pyrazine; pyridine.