The supramolecular chemistry of metal complexes with heavily substituted imidazoles as ligands: Cobalt(II) and zinc(II) complexes of 1-methyl-4,5-diphenylimidazole

An investigation of the M-II/X-/L [M-II = Co, Ni, Cu, Zn: X- = Cl-, Br-, I-, NCS-, NO3-, N-3(-), CH3COO-: L = 1-methyl-4,5-diphenylimidazole] general reaction system towards the detailed study of the intermolecular interactions utilized for controlling the supramolecular organization and the structural consequences on the structures produced has been initiated. Three representative complexes with the formulae [Co(NO3)(2)(L)(2)] (1), [Zn(NO3)(2)(L)(2)] (2) and [Co(NCS)(2)(L)(2)]center dot EtOH (3 center dot EtOH) have been synthesized and characterized by spectroscopic methods and single-crystal X-ray analysis. Compounds I and 2 are isomorphous (tetragonal, I4(1)cd) with their metal ions in a severely distorted octahedral Co/ZnN2O4 environment, while 3 center dot EtOH crystallizes in P2(1)/c with a tetrahedral CoN4 coordination. The structural analysis of 1, 2 and 3 center dot EtOH reveals a common mode of packing among neighbouring ligands (expressed through intramolecular pi-pi interactions between the 4,5-diphenylimidazole moieties), enhancing thus the rigidity and stability of the complexes. The bent coordination of the two isothiocyanates in 3 [Co-NCS angles of 173.8(2) and 160.8(2)degrees] seems to be caused by intermolecular hydrogen bonding and crystal packing effects. (c) 2009 Elsevier Ltd. All rights reserved.