Crystal structure of catena-(dimethylammonium) tris(μ2-formato)copper(II), [C2H8N][Cu(CHO2)3]

Abstract

Source of materialReagents and solvents used were of commercially available quality. The title complex was synthesized according to the method of [1]. Am ixture of Cu(NO 3 ) 2 · 6H 2 O( 0.5 mmol), formic acid (1.7 . mmol), dimethylamine (0.6 mmol) in 20 ml distilled water was refluxed for 2h,and then the resulted solution was kept still and allowed to evaporate at room temperature. Afew days later, blue single crystals suitable for X-ray diffraction study were obtained by slow evaporation of the resulted solution in yield of about 30 %. Experimental details DiscussionThe design and synthesis of porous metal-organic frameworks (MOFs) is currently an active research area due to their intriguing structural architectures as well as potential applications in catalysis, gas adsorption and separation [2][3][4][5]. In order to achieve such functionalities, the common strategy for the construction of porous metal-organic networks is based primarily on the proper selection of inorganic building blocks as nodes and long rigid organic polycarboxylate ligands as linkers [6] to form a3Drobust framework [7,8]. However, formate anions, HCOO − ,which is the simplest carboxylate, has been used very seldom as ab uilding block, although simple metal-formate hydrates have long been known. Even now, example of formate coordination polymers with porous structure is still scarce [1]. Two crystal structures of the title complexe's polymorphs have been studied [9,10]. These polymorphs have significant different unit cell parameters, which crystallize in the space groups I2/c [9] and C2/c [10], respectively. The central Cu atom is coordinated by six Oofformate anions completing its octahedral coordination sphere ( figure, top). The mean Cu-Odistance is 2.110(2) Å and the bond angles around Cu sites are 88.71(6)°-91.29(6)°for cis O−Cu−Oangles and 180.0°for trans O−Cu−Oangles, characterizing the distortion of the CuO 6 octahedra. Every formate anion connects two metal atoms in m 2-bridging coordination mode antianti.The neighbouring Cu···Cu seperation is 6.009(6) Å,which is much longer than that in Co 3 (HCOO) 6 in literature [5]. The m 2 -bridging formate ligands link the metal atoms into a3Dnetwork. The free dimethylammonium cations occupy the structural cavities (figure, bottom) and nitrogen atom of dimethylammonium was disordered over three symmetry positions with occupancy of 1/3.