The Structure of Monomeric Hydroxo-C-II Species in Cu-CHA. A Quantitative Assessment

Using EPR and HYSCORE spectroscopies in conjunction with ab initio calculations, we assess the structure of framework-bound monomeric hydroxo-Cu-II in copper-loaded chabazite (CHA). The species is an interfacial distorted square-planar [(CuOH)-O-II(O-8MRs)(3)] complex located at eight-membered-ring windows, displaying three coordinating bonds with zeolite lattice oxygens and the hydroxo ligand hydrogen-bonded to the cage. The complex has a distinctive EPR signature with g = [2.072 2.072 2.290], (Cu)A= [30 30 410] MHz, and (H)A = [-13.0 -4.5 +11,5] MHz, distinctively different from other Cu-II species in CHA.