Syntheses and Crystal Structures of Three-Dimensional Cyanocadmate Clathrates with Imidazole

The crystal structures of two clathrates with imidazole (=imH), Cd₃(CN)₆(imH)₂]·C₆H₁₂, I, and Cd₃(CN)₆(imH)₂]·C₆H₅Cl, II, have been analyzed by single-crystal X-ray diffraction methods. Clathrate I crystallizes in the monoclinic system, space group P2₁/n with a=13.416(2), b=14.140(2), c=14.151(1)Å, β=105.08(9)°, V=2592.1(5)&Aringsup3;, Z=4, R ₁=0.0360, wR ₂=0.0850 for 5931 independent reflections; II: monoclinic P2₁/n, a=12.369(2), b=14.313(2), c=14.416(4)Å, β=106.04(2)°, V=2452.7(9)&Aringsup3;, Z=4, R ₁=0.0398, wR ₂=0.1105 for 5642 independent reflections. The three-dimensional host structures of clathrates I and II are isostructural with each other. The host framework is built through cyanide bridges among two kinds of Cd ions, tetrahedral and octahedral, in a ratio of 2 : 1. The tetrahedral Cd(1) centre is linked to three octahedral Cd(3) atoms and one tetrahedral Cd(2) atom; the tetrahedral Cd(2) centre is ligated by one unidentate imidazole ligand and linked to one tetrahedral Cd(1) atom and two octahedral Cd(3) atoms; the octahedral Cd(3) centre is ligated by one unidentate imidazole ligand and linked to three tetrahedral Cd(1) atoms and two tetrahedral Cd(2) atoms. The novel host structure provides two types of channels, a large, elongated, rectangular channel and a small rectangular channel. The larger channel is occupied by imidazole ligands coordinated to tetrahedral Cd(2) and octahedral Cd(3). The smaller channel accommodates the guest molecules cyclohexane and chlorobenzene.