2015. 56, 1 UDC 543.422:547.12 CRYSTAL STRUCTURE, SPECTROSCOPY, AND THEORETICAL CALCULATIONS OF TWO BIS(BENZIMIDAZOLYL)BUTANE DERIVATIVES G.-Y. Li1, J.-S. Hu1, Y.-F. Liu2, G.-H. Cui1 1College of Chemical Engineering, Hebei United University, Tangshan, P. R. China 2College of Physics and Electronical Engeering, Henan Normal University, Xinxiang, P. R. China E-mail: tscghua@126.com Received May, 18, 2013 Two ligands for coordination compounds incorporating benzimidazole moieties, namely 1,1butane-1,4-diylbis(5,6-dimethyl-1H-benzimidazole) and 1,1-butane-1,4-diylbis(1H-benzimidazole), are synthesized and then characterized both experimentally and theoretically. <...> Their structures are studied by single crystal X-ray diffraction, UV-Vis spectroscopy, and FT-IR spectroscopy. <...> The optimized geometries, vibrational frequencies, vertical excitation energies of the two ligands are calculated using the (TD)DFT/B3LYP/TZVP method. <...> The calculated results reproduce the experimental data. <...> Additional bonding information about the coordinated N atoms in the two ligands is obtained by FMO and NBO analysis to investigate the substitutegroup effect on the coordination ability. <...> The results confirm that the ligand with electrondonating methyl groups on the benzimidazole moieties has a stronger coordination ability. <...> INTRODUCTION A coordination polymer (CP), also called the metal organic framework (MOF), was first systematically studied by Australian chemist R. Robson in around 1990 [ 1, 2 ]. <...> All of them are composed of metal ions (or metal ion clusters) and organic bridging ligands. <...> The coordination modes of the ligand play an important role in the construction of CPs [ 14 ]. <...> Thus, a selection of a suitable organic ligand with certain flexibility is crucial to the construction of CPs. <...> Bis(benzimidazolyl)alkane derivatives were widely used as bridging ligands to construct CP materials [ 14—16 ]. <...> Different supramolecular structures were obtained by only a subtle change in the substituted group of the benzimidazole moiety [ 15 ]. <...> Structures of (a) the ligand a and (b) the ligand b applications of benzimidazole have led us to investigate the coordination behaviour of different substituted benzimidazole derivatives with transition metal ions. <...> It is known that substituents bonded to the benzimidazole moiety could influence the electronic characteristics of the ring by either donating electrons or withdrawing electrons. <...> In this way <...>