The role of steric constraints in the formation of rare aqua bridged coordination polymers: Synthesis, characterization and X-ray structures of polymeric, [Cu(2-chlorobenzoate)(2)(beta-picoline)(2)(mu-H2O)](n) and monomeric, [Cu(2-chlorobenzoate)(2)(gamma-picoline)(2)(H2O)]

Reaction of hydrated copper(II) 2-chloro-benzoate with beta-/gamma-picoline in methanol: water mixture (4:1 v/v) yielded polymeric [cu(2-chlorobenzoate)(2)(beta-picoline)(2)(mu-H2O)](n); 1 and monomeric [Cu(2-chlorobenzoate)(2)(gamma-picoline)(2)(H2O)]; 2. The newly synthesized complexes have been characterized by elemental analyses, FT-IR spectroscopy, UV-Visible spectroscopy, TGA and single crystal X-ray structure determination. X-ray crystallographic analysis revealed that both complexes crystallize in the monoclinic crystal system with space group and unit cell dimensions: (C2/c; a = 51.71 angstrom, b = 10.58 angstrom, c = 10.02 angstrom and beta = 100.5 degrees for 1 and P2(1)/c; a = 11.81 angstrom, b = 16.33 angstrom, c = 13.79 angstrom and beta = 90.77 degrees for 2. Whereas in 1 the presence of constituent and mediating water molecules running along a-axis gives rise to 1-dimensional zig-zag polymer chains, in complex 2, the presence of square pyramidal arrangement of ligands around copper(II) center results in monomeric structure. Various non-covalent interactions like O-H ... O, C-H ... O and C-H ... pi have been observed to play a decisive role in the stabilization of crystal lattices in both complexes.