Syntheses, structures, and properties of seven-coordinate calcium(II) and five-coordinate lead(II) complexes with 1-D structures

Two new 1-D heterometallic coordination polymers (CPs), {[Ca(NiL)(H2O)(4)]center dot 3H(2)O}(n) (1) and {[Pb(NiL)(H2O)(2)]center dot 3H(2)O)}(n) (2), have been prepared by reactions of CaCl2 and NiL and Pb(NO3)(2) and NiL in CH2Cl2-H2O center dot H2L denotes dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo-9,10-benzo-[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. Single-crystal X-ray diffraction studies show that the coordination geometries around Ni(II) in both 1 and 2 are similar distorted N-4 square planar. All Ni-N bonds are short. Complex 1 has 1-D zigzag chain, while 2 shows 1-D head-to-tail structure. In crystals 1 and 2, 1-D CP chains were parallel-packed and 3-D supramolecular networks were formed via weak hydrogen bond interactions between aqua ligands and lattice water. The effects of water on the assemblies of the two CPs are discussed. Coordinated water plays an important role on the assembly procedure.