Crystal structure of a cadmium sulfate coordination polymer based on the 3,6-bis-(pyrimidin-2-yl)-1,4-di-hydro-1,2,4,5-tetra-zine ligand

Abstract

The polymeric title compound, poly[aqua-hemi[μ₂-3,6-bis-(pyrimidin-2-yl)-1,4-di-hydro-1,2,4,5-tetra-zine](μ₃-sulfato)-cadmium(II)], [Cd(SO₄)(C₁₀H₈N₈)_0.5(H₂O)] _n , (I), represents an example of a three-dimensional coordination polymer resulting from the reaction of CdSO₄·8/3H₂O with 3,6-bis-(pyrimidin-2-yl)-1,4-di-hydro-1,2,4,5-tetra-zine (H₂bmtz, C₁₀H₈N₈) under hydro-thermal conditions. The Cd^II atom has a distorted octa-hedral coordination environment defined by two nitro-gen atoms from one H₂bmtz ligand, three oxygen atoms from three different sulfate anions, and one oxygen atom from a coordinating water mol-ecule. The 1,4-di-hydro-1,2,4,5-tetra-zine ring of the H₂bmtz ligand is located about an inversion center, with the NH group being equally disordered over two sites. The sulfate anion acts as a μ₃-bridging ligand to connect three Cd^II atoms, resulting in the formation of [Cd(SO₄)(H₂O)] sheets propagating parallel to the bc plane. Adjacent sheets are inter-connected across the H₂bmtz ligands, which coordinate the Cd^II atoms in a bis-bidentate coordination mode, to form a three-dimensional framework structure. The framework is further stabilized by classical O-H⋯O hydrogen bonds involving the coordinating water mol-ecules and the sulfate groups, and by N-H⋯O hydrogen bonds between the disordered tetra-zine NH groups and sulfate oxygen atom, along with C-H⋯π and π-π stacking [centroid-to-centroid separation = 3.5954 (15) Å] inter-actions between parallel pyrimidine rings of the H₂bmtz ligand.

Keywords: bis-bidentate coordination mode; cadmium(II); coordination polymers; crystal structure; tetra­zine.