Synthesis and Crystal Structures of Alkali and Alkaline Earth Metal Complexes of 3,5‐Dinitropyrazolyl‐4‐carboxylate

Abstract

The synthesis and crystal structures of 3,5‐dinitro‐1H‐pyrazolyl‐4‐carboxylic acid (H2dnpzc) and its four complexes with Ca2+, Ba2+, Na+ and K+ are reported in this paper. Ca(dnpzc)·5H2O exhibits a 1D polymeric structure, whereas Ba(dnpzc)·4H2O possesses a 2D structure. The structure of Na2(dnpzc)·4H2O consists of 2D layers of [Na(dnpzc)]–n and 1D chains of [Na(H2O)3]+n. K2(dnpzc)·H2O has a true 3D structure. It was observed that the doubly deprotonated ligand (dnpzc2–) can act as a versatile bridge to form polymeric structures by varying combinations of its 8 potential donor atoms (two carboxy O atoms, two pyrazolyl N atoms and four nitro O atoms). Particularly in the structure of K2(dnpzc)·H2O, all the 8 donor atoms of dnpzc2– take part in the coordination and as many as 10 potassium atoms are connected by one ligand.