Crystal structure of (µ2-5-bromoisophthalate-κ2O:O’)bis(2-methyl-4Himidazole- κN)cobalt(II), C16H15BrCoN4O4

Abstract

Source of materialAm ixture of Co(NO 3 ) 2 ×6H 2 O( 0.1 mmol, 0.0267 g), 5-bromoisophthalic acid (0.15 mmol, 0.025 g), 2-methyl-4H-imidazole (0.02 mmol, 0.0352 g) and distilled water (10 mL) was heated in a 25mLstainless steelreactor with aTeflon liner 403 Kfor 36 h, followed by slow cooling to room temperature. Red crystals of the title compound formed. Experimental detailsThe hydrogen atomswere assigned with commonisotropic displacementf actors U iso (H) =1 .2 U eq (N and imidazole C), or U iso (H) =1.5 U eq (methyl C) and included in the final refinement by using geometrical restraints, with C-H =0.93 Å(imidazole) or C-H =0.96 Å(methyl), and N-H =0.86 Å. DiscussionMetal-organic coordination polymers have attracted considerable attention because of their potential applications as functional materials as well as their structure diversity and intriguing variety of topologies [1,2].The diversity in the framework structures of such materials greatly depends on the metal centers and the structure of thespacer ligands, as well as on the reaction pathway [3]. Although alarge number of polycarboxylate based coordination polymers have been synthesized, systematic investigation of external physical or chemical stimuli effects on the structures of polycarboxylate based coordination polymers remains rare [4][5][6][7].Itisnoteworthy that imidazole and isophthalic acid have been widely used to prepare suchh ybridc omplexes. Bis(imidazole) ligandswith -CH 2 -spacers are good candidates for N-donor bridging ligands.The flexiblenature of -CH 2 -spacers allows the ligands to bend and rotatefreelywhen coordinating to metal centers so as to conformtothe coordination geometries of metal ions [8,9].The previousstudies showthat theseligands canexhibitspecial abilitiestoformulate interesting compounds, andthe results also indicate that different organic anions playimportantr oles in directing to the finals tructures and topologies [10].Inthis paper we reportthe crystal structure of anovel hybrid compound. Theasymmetric unitofthe title structurecontains one Co(II) ion, two2 -methyl-4H-imidazole andl igands5 -bromoisophthalatedianion as abridging ligand to construct anew coordination polymer. Thecobaltatom is four-coordinated in adistorted tetrahedron by two oxygen atoms( O1 and O4)f rom isophthalateligands andtwo nitrogenatoms (N3 andN4) from two2-methyl-4H-imidazole ligands.The Co-Obondlengths are 1.989(2) Åa nd 2.008(2) Å, andt he Co-N bond lengths are 2.021(3) Åand 2.025(3) Å, respectively. TheO1-Co1-N4angle is 110.38(9)°,t he N3-Co1-N4 angle is 125.69(10)°, the O1-Co1-N3 angle is 97.32(10)°, the O1-Co1-O4 angle is 101.32(9)°. In the imidazole ring the C1-N3 bond lengths is 1.326(4) Å, which is shorter than the single bond value. The Co1-N4-C5-C8 torsion angle is -1.6(4)°, the Co1-N3-C1-C4 torsion angle is -2.3(5)°.