Crystal structure of polymeric bis­(3-amino-1H-pyrazole)­cadmium diiodide

The title compound, {[Cd(3-apz₂)]I₂}_n consists of a Cd²⁺ cation, iodine anions balancing the charge and bridging 3-amino­pyrazole (3-apz) mol­ecules. The Cd²⁺ cations are coordinated by two iodine anions and two apz ligands, generating trans-CdN₄I₂ octa­hedra, and are linked into chains by pairs of the bridging ligand. In the crystal structure, the apz ligands and iodide anions of neighboring chains are linked through inter­chain hydrogen bonding into a two-dimensional supra­molecular network.

The reaction of cadmium iodide with 3-amino­pyrazole (3-apz) in ethano­lic solution leads to tautomerization of the ligand and the formation of crystals of the title compound, catena-poly[[di­iodido­cadmium(II)]-bis­(μ-3-amino-1H-pyrazole)-κ²N²:N³;κ²N³:N²], [CdI₂(C₃H₅N₃)₂]_n or [CdI₂(3-apz)₂]_n. Its asymmetric unit consists of a half of a Cd²⁺ cation, an iodide anion and a 3-apz mol­ecule. The Cd²⁺ cations are coordinated by two iodide anions and two 3-apz ligands, generating trans-CdN₄I₂ octa­hedra, which are linked into chains by pairs of the bridging ligands. In the crystal, the ligand mol­ecules and iodide anions of neighboring chains are linked through inter­chain hydrogen bonds into a di-periodic network. The inter­molecular contacts were qu­anti­fied using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative qu­anti­tative contributions of the weak inter­molecular contacts.