Preparation, crystal structures and conformations of six complexes based on 1,4-bis(benzimidazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene?

CrystEngComm Pub Date: 2014-06-03 DOI: 10.1039/C4CE00215F

Abstract

Reaction of ligands (L or LA) with metal salts affords six new metal complexes {[Mn(L)3](ClO4)2}n (1), [Cu(L)(SO4)(H2O)]·1.5H2O (2), [Co(L)(LA)(CH3OH)2]·2CH3OH (3), [Co(L)(DMF)(NO3)2]n (4), [Cd(L)(DMF)(NO3)2]n (5) and [Cu(L)(DMF)(NO3)2]n (6) (L = 1,4-bis(benzimidazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene, LA = fumarate). These complexes are structurally characterized by X-ray diffraction analyses. Analyses of crystal structures of complexes 1 and 2 show that 2D layers with metallomacrocycles are formed via ligand L and metal atoms (Mn(II) for 1 and Cu(II) for 2). The 2D layer with metallomacrocycles in complex 3 is formed via ligand L, fumarate groups and Co(II) atoms. 1D polymeric chains in complexes 4–6 are formed via ligand L and metal atoms (Co(II) for 4, Cd(II) for 5 and Cu(II) for 6). In the crystal packing of complexes 1–6, 3D supramolecular frameworks are formed via intermolecular weak interactions, including π–π interactions and C–H?π contacts. π–π interactions between benzimidazole rings are compared. The conformations of metal complexes based on dibenzimidazolyl bidentate ligands with flexible or semi-rigid linkers are described and compared. Additionally, the fluorescence emission spectra of ligand L and metal complexes and the magnetic properties of complexes 2–4 are reported.

Graphical abstract: Preparation, crystal structures and conformations of six complexes based on 1,4-bis(benzimidazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene
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