Coordination Compounds of Transition Metals with Rhodanine-3-Acetic Acid

Seven compounds are synthesized by the reactions of the transition metals with rhodanine-3-acetic acid and studied by X-ray structure analysis. The compositions of the compounds can be presented by the formulas: [Co(Rda)(2)(H2O)(4)] (I), [Ni(Rda)(2)(H2O)(4)] (II), [Zn(Rda)(2)(H2O)(4)] (III), [Zn(5,5'-Rda-Rda)(Dmf)(2)(H2O)(2)](n) (IV), [Co(Rda)(2)(bipy)(H2O)(2)](n) (V), [Cd(Rda)(2)(Bpe)](n) (VI), and [Co(Gly)(3)].H2O (VII), where 5,5'-Rda-RdaH(2) is the new ligand (condensation product of two RdaH molecules), bipy is 4,4-bipyridine, Bpe is bis(4-pyridyl)ethane, and Gly is glycine (CIF files CCDC nos. 2070334-2070339 for I-VI, respectively). Compounds I-III and VII are mononuclear molecular complexes, and compounds IV-VI are 1D coordination polymers. In complexes I-III, Rda coordinates via one oxygen atom of the carboxyl group as the monodeprotonated monodentate ligand, whereas in compound VII this ligand undergoes decomposition due to the solvothermal synthesis to form glycine molecules. Polymer IV is formed by the new ligand (5,5'-Rda-Rda)(2-) that coordinates as the bis(deprotonated) bidentate-bridging ligand, and molecules of the bis(pyridine) class (bipy and Bpe) act as bridging neutral ligands in compounds V and VI. In compound V, Rda coordinates as in complexes I-III, whereas in polymer VI two crystallographically independent Rda ligands coordinate via different modes: one ligand coordinates via the bidentate-chelating mode to one cadmium atom, and another coordinates via the tridentate-chelating mode to two metal atoms.