Crystal structure of poly[µ2-1,4-di(1H-imidazol-1-yl)butan-κ2N:N'-µ2-thiophene-2,3-dicarboxylato-κ4O,O':O'',O'''nickel(II)], C16H16N4NiO4S

Abstract

Source of materialA mixture of H 2 tpda (2,3-thiophene dicarboxylic acid, 0.1 mmol), Ni(OAc) 2 ·4H 2 O (0.1 mmol ), bib (1,4-bis(imidazol-1-yl)butane, 0.1 mmol) and distilled water (10 mL) was sealed in a 25 mL Teflon lined stainless-steel reactor, heated to 433 K and kept at constant temperature for 5 days. Slow cooling to room temperature gave yellow block-like crystals of the title compound. DiscussionThe design and construction of metal-organic frameworks (MOFs) with well-regulated network structures has been provoked significant interest on these functional materials with properties, such as electrochemistry, photophysics, catalysis, adsorption and separation [1][2][3][4]. The organic ligands, which have their differences in the size, the flexibility, the coordination ability, the number of the carboxylate groups, the positions of the carboxylate groups and so on, play crucial role in the design and construction of desirable frameworks with interesting properties [5][6][7][8]. In addition, N-containing auxiliary ligands are known to be ideal connectors between metal atoms for the propagation of coordination networks. With these considerations in mind, we have chosen the tpda and bib as bridging ligands to construct a new complex. The asymmetric unit contains one Ni(II) ion, one completely deprotonated tpda 2-anion and one bib molecule, as shown in the Fig. The nickel atom is six-coordinated [NiN 2 O 4 ] in a distorted octahedral manner. The equatorial plane is consisted of four carboxyl oxygen atoms from two tpda 2-ligands, while two nitrogen atoms from two bib molecules locate at the axial positions. All the Ni-O bond lengths are in the range of 2.1331(17) -2.1443(18) Å and the Ni-N bond distance is 2.055(2) Å. Along the crystallographic c axis, the tpda 2-ligands bridge the Ni(II) centers to form 1D carboxylate chains, which are interconnected to each other through the bib molecules to result in a 3D metal-organic framework.