Crystal structure of hexaquamanganese(II) (4-carboxythiophene-3- carboxylate hemihydrate, C12H16MnO16S2

Abstract

Source of materialAm ixture of Mn(CH 3 COO) 2 ×4H 2 O( 0.25 mmol, 0.006 g) and thiophene-3,4-dicarboxylic acid (0.50 mmol, 0.086 g) were dissolved in 10 mL H 2 O. The solution was heated in a23mLTeflon lined autoclave under autogenous pressure at 403K for three days. After cooling to room temperature, pink block-shaped crystals that formed were collected. Thepink crystals suitable for X-ray diffraction analysis were collected. Experimental detailsOn thet hiophene ring,t he hydrogen atoms were assigned with U iso (H) =1.2 U eq (C), and included in the final refinement by using geometrical restraints, with d(C-H) =0.93 Å. Adata completeness of only 97.2 %was achieved. DiscussionThe study and design of new metal complexes is of current interestininorganic chemistryaswell as in materials science. In recent years, the synthetic efforts have been particularly directed towards the preparation of molecular-based magnetic materials [1],conducting compounds with extended structures and of materials with zeolite-like structures [2][3][4]. The design and evaluation of coordination compounds which are able to build extended chain, layerorthree-dimensional structures has many interesting aspects. Oneg oali nt hisf ield is thed evelopment of synthetic routes forthe molecular engineering. Asecond goal is to develop molecular ferromagnets on the basis of three-dimensional structures [5]. Among the reported studies about the construction of such complexes, versatile multicarboxylate ligands such as benzenepolycarboxylates, pyridinecarboxylates, and imidazolecarboxylates have been extensively employed to construct new complexes owing to their rich coordination modes and strong coordination ability [6][7][8].Asignificant number of reports have been contributed to the use of thiophene and thiophene derivatives as ligands. These are useful and important organic moieties for the synthesis of electronic and optical materials owing to their good electron-transferring ability and structural rigidity [9][10][11][12]. However, newc omplexes constructedf romt hiophene-based compounds are rather limited and most of the work has been devoted on complexes builtf rom commercially available thiophene-2,5-dicarboxylic acid. Considering structural rigidity, thiophene-3,4-dicarboxylic acid (H 2 tdc)a nd its deprotonated analoga are good bridging ligands for constructing new complexes. The title structure consists of discrete ionic entities. Alabeled diagram of the strucutre is shown in the figure. In the cations, the metal atom is surrounded by six aqua ligands, exhibiting aslightly distorted octahedral geometry. The Mn-O bonding distances are Mn1-O2 =2.235(4), Mn1-O3 =2.172(3), Mn1-O4 =2 .157(3) Å. Thei ntramolecular hydrogen bond produces a short O×××Odistance: O6×××O6#2 =2.429(5) Å. Theintermolecular hydrogen bonds result in athree-dimensional polymer.