Crystal structure of tris{2,2′-[1,2-[methylenebis(thio)]-bis[1,3,4-thiadiazole]]}copper(II) tetranitrate — acetonitrile (1:1), Cu2(C5H4N4S4)3(NO3)4 · CH3CN

Abstract

Source of materialThe reaction of 1,2-[methylenebis(thio)]bis [1,3,4-thiadiazole] (0.2 mmol) with Cu(NO 3 ) 2 (0.1 mmol) in MeOH (10 mL) for a few minutes afforded al ight-blue solid, which was filtered, washed with acetone, and dried in air. The single crystals suitable for X-ray diffraction analysis were obtained by slow diffusion of Et 2 Ointo the acetonitrile solution. DiscussionIn recent years, the rational design of coordination polymers based on multi-topic or flexible bridging ligands as linkers and metal centers as connectors represents one of the most rapidly developing fields owing to their potential as functional materials in electronic, magnetic, optical, catalytic applications [1][2][3]. In particular, the use of flexible ligands in such studies have attracted remarkable attention because the flexibility and conformation restrainability of such ligands offer the possibility for the construction of diverse frameworks. Meanwhile, thiadiazoles have attracted increasing attention because of their potential applications in pharmaceutical, agricultural, industrial, coordination and polymer chemistry [4][5][6]. In this sense, flexible bisthiadiazole alkanes, like 2,2'-[1,2-ethanediylbis(thio)]bis [1,3,4-thiadiazole], show up as good candidates to generate one-, two-and threedimensional network [7].In the title crystal structure, the asymmetric unit consists of two Cu 2+ ions, three thiadiazole ligands, four NO3 -ions and one acetonitrile molecule. The Cu1 center has as lightly distorted octahedral environment (CuN 4 O 2 )with four Natoms from four thiadiazole ligands and two Oatoms from two NO 3 -ions in trans positions. However, the Cu2 adopts adistorted tetragonal pyramid (CuN 2O3), with two Natoms from two thiadiazole ligands and three Oatoms from three NO 3 -ions. All Cu-Nbond distances are within the range expected for such coordination [7,8]. Only the Natoms of the thiadiazole ligands coordinate to Cu centers. All thiadiazole ligands adopts a N,N-bidentate bridging mode in trans configuration and bridge the copper atoms into a two-dimensional network, with the bridged Cu···Cu distances of 10.4917(4), 10.5769(5) and 10.8052(7) Å,r espectively. The layers are further interconnected by C-H···Oand C-H···Nhydro-gen bonds into athree dimensional network. The centroid separation and dihedral angle of thiadiazole rings are 6.3441(3), 6.3445(3), 6.4678(3) Å and 69.28°,72.11°,78.39°,respectively. However, two thiadiazole rings are almost coplanar with the centroid separation of 7.8596(8) Å.A pparently, incorporation as a bridging ligand into metal-organic frameworks imparts significantly conformation changes in the thiadiazole ligand. One NO 3 -ion adopts monodentate coordination mode and serves to complete the coordination sphere of one copper atom. The other NO 3 -ion adopts bridging mode and bridge the two neighbouring copper atoms (Cu1 and Cu2), which stabilizes the network. The space between the layers is taken up by acetonitrile molecules.