CH⋯Pd interactions: one dimensional heteropolynuclear complexes.

Three cyanide complexes, [Cu(hepH)2Pd(μ-CN)2(CN)2]n (1), [Zn(hepH)2Pd(μ-CN)2(CN)2]n (2) and [Cd(hepH)2Pd(μ-CN)2(CN)2]n (3) (2-pyridineethanol abbreviated to hepH), have been synthesized and characterized by various techniques (elemental analysis, FT-IR and Raman spectroscopy, thermal analysis and single crystal X-ray diffraction). FT-IR spectroscopy pointed out the existence of terminal and bridged cyanide ligands in the complexes. The crystallographic analyses reveal that complexes 1 and 2 crystallize in the triclinic system, space group P-1 and complex 3 crystallizes in the monoclinic system, space group P2₁/n. The palladium atom is coordinated with cyanide-carbon atoms in a square-planar arrangement and the metal(II) atoms are six-coordinated with two cyanide nitrogen, two hepH nitrogen and two hepH oxygen atoms, in a distorted octahedral arrangement. In all the complexes adjacent chains are connected by CH⋯Pd, π⋯π and OH⋯N hydrogen bonding interactions to form two- and three-dimensional networks. When it comes to thermal analysis, the complexes followed usual decomposition mechanism in which neutral ligands (hepH) are released first, and then cyanide ligands are decomposed. The final decomposition products are found to be the corresponding metal oxides.