Hydrogen reduction of the Cu(acac)2 complex sorbed by cucurbit[8]uril

The hydrogen reduction of bis(2,4-pentanedionato)copper(II) sorbed by the cavitand cucurbit[8]uril has been studied. After sorption of the complex at 180A degrees C, the crystal structure of the resulting phase differs from the structure of the individual compounds. EPR shows that the reduction of the complex with hydrogen at 250A degrees C for 15 min leads to the loss of one of the ligands and formation of the coordination bond between the Cu2+ ion and a nitrogen atom of cucurbit[8]uril and the oxygen atom of the water molecule or OH- group located in the cavitand cavity. The molecular structure of the resulting supramolecular compound has been optimized by density functional theory quantum-chemical calculations with the exchange-correlation functional with the use of the PRIRODA program package. EPR, EXAFS, and XANES show that an increase in the reduction time or temperature (to 280A degrees C) leads to the formation of copper clusters.