Cadmium(II) iodide molecular coordination compounds with 4-methylpyridine and 4-methylquinoline

The coordination compounds [CdI2(4-MePy)2] (I) and [CdI2(4-MeQuin)2] (II) where Quin is quinoline have been synthesized, and their structure has been solved. Crystals of complex I are monoclinic, space group C2/c, a = 13.353(1) Å, b = 16.653(1) Å, c = 14.380 (1) Å, β = 103.17(1)°, V = 3113.5(4) Å3, ρcalcd = 2.425 g/cm3, Z = 8. Crystals of complex II are monoclinic, space group P21/c, a = 10.647(1) Å, b = 25.264(1) Å, c = 8.610(1) Å, β = 113.73(1)°, V = 2120.1(3) Å3, ρcalcd = 2.044 g/cm3, Z = 4. Polymer [CdI2(4-MePy)2]∞ chains running in the direction [001] are formed in the structure of complex I. Each of the two crystallographically nonequivalent Cd(1) and Cd(2) atoms are octahedrally surrounded by the four iodine and two nitrogen atoms of the 4-MePy ligand. The Cd(1)⋯Cd(2) distance in a chain is 4.33 Å. The structure of complex II is built of [CdI2(4-MeQuin)2] discrete neutral clusters. The two iodine and two nitrogen atoms of the 4-MeQuin ligand participate in the coordination of the Cd2+ ion. The cadmium coordination polyhedron is a distorted tetrahedron (Cd-Iavg, 2.72 Å; Cd-Navg, 2.30 Å; angles N(I)CdN(I), 98.3–121.8°). The minimum and maximum values correspond to the ICdI angle and NCdN angle, respectively. Complex I is photoluminescent in the solid state at room temperature.