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 MII/X−/L [MII = Co, Ni, Cu, Zn; X− = Cl−, Br−, I−, NCS−, NO3−, N3−, 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]·EtOH (3·EtOH) have been synthesized and characterized by spectroscopic methods and single-crystal X-ray analysis. Compounds 1 and 2 are isomorphous (tetragonal, I41cd) with their metal ions in a severely distorted octahedral Co/ZnN2O4 environment, while 3·EtOH crystallizes in P21/c with a tetrahedral CoN4 coordination. The structural analysis of 1, 2 and 3·EtOH reveals a common mode of packing among neighbouring ligands (expressed through intramolecular π–π 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)°] seems to be caused by intermolecular hydrogen bonding and crystal packing effects.

Two isomorphous, octahedral cobalt(II) and zinc(II) nitrato complexes and one tetrahedral, cobalt(II) isothiocyanato complex, all with two 1-methyl-4,5-diphenylimidazole ligands, possess a characteristic mode of packing between neighbouring ligands of the complexes, expressed through intramolecular π–π interactions between the 4,5-diphenylimidazole moieties.Figure optionsDownload as PowerPoint slide