Syntheses and Crystal Structures of Manganese(II), Cadmium(II), Cobalt(II), and Zinc(II) Complexes with 4-Pyridyl Dithioether Ligands

The reactions of three structurally related flexible pyridyl dithioether ligands, 1,2-bis(4-pyridylthio)ethane (L), 1,3-bis(4-pyridylthio)propane (L), and 1,5-bis(4-pyridylthio)pentane (L), with Mn(ClO4)2·6H2O, Cd(ClO4)2·6H2O, Co(ClO4)2·6H2O, and Zn(ClO4)2·6H2O led to the formation of four new complexes:  {[Mn(L1)2(H2O)2](L1)2(ClO4)2(CHCl3)2}∞ (1), {[Cd(L2)2(H2O)2](ClO4)2(H2O)3}∞ (2), {[Co(L3)2(H2O)2](ClO4)2(H2O)3}2 (3), and {[Zn(L3)2(H2O)2](ClO4)2(H2O)3}2 (4), which have been characterized by elemental analyses, IR spectroscopy, and X-ray crystallography. Single-crystal X-ray analyses show that complex 1 is a unique one-dimensional chain containing cage unit,
2 is a double-stranded chain structure, and 3 and 4 are binuclear cage molecules. In the complexes, all the ligands
adopt N,N-bidentate bridging coordination mode using the two pyridyl nitrogens to coordinate to metal centers. In
complexes 1 and 2, the uncoordinated sulfur atoms show interchain weak S···S interactions, by which two 1-D
chains are linked to two different 2-D supramolecular networks. Additional weak C−H···O hydrogen bonds further
connect complex 1 into a 3-D supramolecular architecture. These S···S contacts and C−H···O hydrogen bonds also
help to stabilize the crystal structures of these complexes.