Syntheses, Structures, and Properties of Honeycomb and Square Grid Coordination Polymers with In Situ Formed 5-(2′-Pyrimidyl)tetrazolate

Solvothermal reactions of Zn(II), Cd(II), Mn(II), Co(II), or Ni(II) salts and 2-pyrimidinecarbonitrile (pymCN) in the presence of NaN<sub>3</sub> in DMF yielded seven metal−organic coordination polymers formulated as [Zn(pymtz)<sub>2</sub>]<sub><i>n</i></sub> (<b>1</b>), [NaM<sup>II</sup>(pymtz)<sub>3</sub>]<sub><i>n</i></sub>·G (M = Zn <b>2</b>, Cd <b>3</b>, Mn <b>4</b>, Co for <b>5</b>, and Ni for <b>6</b>; G = DMF and/or H<sub>2</sub>O) and [Cd(pymtz)<sub>2</sub>]<i><sub>n</sub></i> (<b>7</b>) [pymtz = 5-(2′-pyrimidyl)tetrazolato]. Compounds <b>2</b>−<b>6</b> are isomorphous and all contain neutral honeycomb layers in which pymtz serves as a bis(chelating) bridge between M(II) (M = Zn for <b>2</b>, Cd for <b>3</b>, Mn for <b>4</b>, Co for <b>5</b>, and Ni for <b>6</b>) and Na<sup>+</sup>, and the ellipse stacking of the layers generates one-dimensional hexagonal channels. Compounds <b>1</b> and <b>7</b> exhibit different (4,4) square grid networks. In <b>1</b>, the Zn ions are octahedrally coordinated and linked by pymtz ligands in the μ<sub>2</sub> tridentate bridging mode, while in <b>7</b>, the Cd(II) ions are eight-coordinated with a square prismatic geometry and bridged by bis(chelating) pymtz ligands. Compounds <b>2</b> and <b>3</b> can transform into <b>1</b> and <b>7</b>, respectively, by immersing the sample in appropriate solvents. Interestingly, photoluminescence measurements on Zn(II) and Cd(II) compounds show that the emission bands can be correlated to the coordination modes of the pymtz ligands.