Anion Directed Assembly of Cu(II) Complexes Formed by a Flexible Ligand

Coordination polymers, consisting of metal, anion and organic ligands, have attracted much attention. The structure of coordination polymers is affected by various factors. To investigate the effects of anion, syntheses and structures of four Cu(II) complexes, namely [(CuLCl2)(PF6)](n) (1), [(CuLCl2)(ClO4)](n) (2), [(CuLCl3)center dot CH3OH](n) (3) and CuLCl3 (4), are reported based on a flexible ligand, 1,3-bis(2-pyridylmethyl)imidazolium (L). The ligand is accommodative to kinds of anions, and forms 1-D chains generally upon reaction with Cu(II) salts. The effect is measured by the conformational variation through the dihedral angles between different aromatic rings of the ligand. In order to further investigate the effect of anion, a protonated sample of L, namely, LH(ClO4)(2)center dot H2O (5) is also synthesized and structurally characterized, showing an intriguing hydrogen bonded helix.