Coordination molecular compounds of cadmium(II) iodide with dimethylpyridines

The reactions of CdI₂ with dimethylpyridines (Me₂Py is C₇H₉N) afford complexes CdI₂(2,3-Me₂Py)₂] (I), CdI₂(2,6-Me₂Py) (II), and CdI₂(3,5-Me₂Py)₂ (III). The structures of compounds I and II are determined. The crystals of complex I are orthorhombic, space group Pbca, a = 7.930(1) Å, b = 15.537(1) Å, c = 29.943(1) Å, V = 3689.1(5) ų, ρ_calcd = 2.090 g/cm³, Z = 8. The crystals of complex II are monoclinic, space group C2/c, a = 14.784(1), b = 11.991(1), c = 17.711(1) Å, β = 90.39(1)°, V = 1081.1(2) ų, ρ_calcd = 2.908 g/cm³, Z = 4. The structure of compound I is built of discrete neutral complexes CdI₂(2,3-Me₂Py)₂]. The Cd polyhedron is a distorted tetrahedron (Cd-I 2.289–2.295, Cd-N 2.708–2.734 Å, angles N(I)CdN(I) 103.1°-114.8°). Polymer chains CdI₂(2,6-Me₂Py)]_∞ extended along the direction 100] are observed due to the bridging iodine atoms in structure II. The Cd polyhedron is a trigonal bipyramid containing iodine atoms at the axial vertices (Cd-I_aks 3.040 Å) and two iodine atoms and the nitrogen atom of the Me₂Py ligand in the equatorial plane Me₂Py (Cd-I_eq 2.840 Å, Cd-N 2.309 Å). The compounds in the solid state are photoluminescent.