Syntheses and structures of bis(2-amino-py-rimi-dine-κN 1)di-chlorido-zinc(II) (ortho-rhom-bic polymorph) and bis(2-am-ino-py-rimi-dine-κN 1)di-iodido-zinc(II).

The title compounds, [ZnCl2(C4H5N3)2] (1) and [ZnI2(C4H5N3)2] (2) (C4H5N3 = 2-amino-pyrimidine), were prepared from a solvent mixture of tri-chloro-methane and methanol and structurally characterized. The asymmetric unit of 1 consists of one ZnII cation that is situated on a twofold rotation axis and one chloride anion as well as one 2-amino-pyrimidine ligand in general positions. The asymmetric unit of 2 is built up of one ZnII cation, two iodide anions and two 2-amino-pyrimidine ligands, all of them located in general positions. In both compounds, the metal cations are tetra-hedrally coordinated by two halide anions and two 2-amino-pyrimidine ligands. In compound 1, the discrete complexes are linked by N-H⋯Cl hydrogen bonds into layers that are further connected by weak C-H⋯Cl inter-actions. In compound 2, the complexes are connected via N-H⋯I hydrogen bonds into layers that are further linked by a number of N-H⋯I and C-H⋯I hydrogen bonds. Compound 1 represents a second polymorphic modification of ZnCl2(C4H5N3)2 that crystallizes in the ortho-rhom-bic non-centrosymmetric space group Pba2, whereas the known form crystallizes in the monoclinic, centrosymmetric space group C2/c [Lin & Zeng (2007 ▸). Acta Cryst. E63, m1597].