The first three-dimensional FeIII–SrIIheterometallic coordination polymer: poly[[diaquatetrakis(μ3-pyridine-2,3-dicarboxylato)diiron(III)strontium(II)] dihydrate]

Abstract

The title compound, poly[[diaqua-1κ2O-tetrakis(μ3-pyridine-2,3-dicarboxylato)-2:1:2′κ10N,O2:O2′,O3:O3′;2:1:2′κ8O3:O3′:N,O2-diiron(III)strontium(II)] dihydrate], {[Fe2Sr(C7H3O4)4(H2O)2]·2H2O}n, which has triclinic (P\overline{1}) symmetry, was prepared by the reaction of pyridine-2,3-dicarboxylic acid, SrCl2·6H2O and Fe(OAc)2(OH) (OAc is acetate) in the presence of imidazole in water at 363 K. In the crystal structure, the pyridine-2,3-dicarboxylate (pydc2−) ligand exhibits μ3-η1,η1:η1:η1and μ3-η1,η1:η1,η1:η1coordination modes, bridging two FeIIIcations and one SrIIcation. The SrIIcation, which is located on an inversion centre, is eight-coordinated by six O atoms of four pydc2−ligands and two water molecules. The coordination geometry of the SrIIcation can be best described as distorted dodecahedral. The FeIIIcation is six-coordinated by O and N atoms of four pydc2−ligands in a slightly distorted octahedral geometry. Each FeIIIcation bridges two neighbouring FeIIIcations to form a one-dimensional [Fe2(pydc)4]nchain. The chains are connected by SrIIcations to form a three-dimensional framework. The topology type of this framework istfj. The structure displays O—H...O and C—H...O hydrogen bonding.