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

Using EPR and HYSCORE spectroscopies in conjunction with calculations, we assess the structure of framework-bound monomeric hydroxo-Cu in copper-loaded chabazite (CHA). The species is an interfacial distorted square-planar [CuOH(O-8MRs)] 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 = [2.072 2.072 2.290], = [30 30 410] MHz, and = [-13.0 -4.5 +11.5] MHz, distinctively different from other Cu species in CHA.