Syntheses and structures of bis(2-aminopyrimidine-κ <i>N</i> ¹ )dichloridozinc(II) (orthorhombic polymorph) and bis(2-aminopyrimidine-κ <i>N</i> ¹ )diiodidozinc(II)

The title compounds, [ZnCl₂(C₄H₅N₃)₂] (<b>1</b>) and [ZnI₂(C₄H₅N₃)₂] (<b>2</b>) (C₄H₅N₃ = 2-amino-pyrimidine), were prepared from a solvent mixture of tri-chloro-methane and methanol and structurally characterized. The asymmetric unit of <b>1</b> consists of one Zn^II 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 <b>2</b> is built up of one Zn^II 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 <b>1</b>, 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 <b>2</b>, the complexes are connected <i>via</i> 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 <b>1</b> represents a second polymorphic modification of ZnCl₂(C₄H₅N₃)₂ that crystallizes in the ortho-rhom-bic non-centrosymmetric space group <i>Pba</i>2, whereas the known form crystallizes in the monoclinic, centrosymmetric space group <i>C</i>2/<i>c</i> [Lin & Zeng (2007 ▸). <i>Acta Cryst.</i> E<b>63</b>, m1597].