Spectroscopic study of the structure of bis(oxazoline)copper complexes in solution and immobilized on laponite clay.: Influence of the structure on the catalytic performance

A bis(oxazoline)copper complex is immobilized in a synthetic Laponite clay by cationic exchange in different conditions. The structure of the exchanged complex is studied by several spectroscopic methods, mainly EPR and EXAFS, and compared with the homogeneous precursors in both solid state and solution. The exchanged copper complexes are isolated species with an almost square-planar structure with the clay surface acting as a counterion of the cationic complex. The strength of the copper-anion interaction, conditioned also by the solvent, allows one to explain the differences in catalytic activity and selectivities between the different homogeneous and supported catalysts.