Crystal structure of cobalt(III) compound with ethylenediamine-N,N′-Di-3-propionic acid, [Co(H2Eddp)(HEddp)]Br2 ⋅ 4H2O

The crystal structure of [Co(H2Eddp)(HEddp)]Br2 ⋅ 4H2O is determined [R1 = 0.0551 and wR2 = 0.1298 for 2580 reflections with I > 2σ(I)]. The structure consists of the [Co(H2Eddp)(tHEddp)]2+ cationic complexes, Br− anions, and molecules of crystallization water. Two tridentate ligands, which differ in the degree of protonation, coordinate the Co atom by two N atoms and one O atom, each forming a meridional isomer. In the complex, the configurations of the N(2) and N(4) atoms, which are included in two chelate rings each, differ from those of the N(1) and N(3) atoms, which are included only in the five-membered rings and bear uncoordinated propionate groups. The Co-N(1) and Co-N(3) bonds are longer than the Co-N(2) and Co-N(4) bonds (mean 1.987 and 1.957 Å, respectively). The Co-O(5) bond with the neutral ligand is longer than the Co-O(1) bond with the negatively charged carboxyl group (1.927 and 1.901 Å, respectively). The C(13)-O(5) carbonyl bond in the coordinated COOH group is elongated to 1.266 Å. The system of hydrogen bonds interlinks the cationic complexes, Br− anions, and water molecules into a three-dimensional framework.