Synthesis, characterization and structure of mononuclear cobalt(III) carbonato complexes containing a tailored tetradentate amine as an end-capping ligand

Two hexacoordinated mononuclear compounds of the type [Co(L)(CO3)]ClO4/PF6 (1/2) [L = N,N'-bis(3-aminopropyl)-1,2-ethanediamine] have been synthesized and characterized using microanalytical, spectroscopic and other physicochemical results. Single crystal X-ray structural analysis shows that the metal center in 1 adopts a distorted octahedral geometry with a CoN4O2 chromophore. Hexacoordination of cobalt(III) is attained by binding with four N atoms of L and two 0 atoms of a chelated carbonate ion. Multiple intermolecular N-H center dot center dot center dot O hydrogen bondings in 1 result in a 2D sheet structure. In MeCN solutions, the diamagnetic compounds show a nearly reversible one-electron reductive response corresponding to cobalt(III)-cobalt(II) couple.