Cu+(H-2) and Na+(H-2) adducts in exchanged ZSM-5 zeolites

Cu(I) ions in Cu-ZSM-5 form Cu+(H-2) complexes, stable at room temperature and sub-atmospheric H-2 pressure, which do not have any homogeneous analogue except for matrix-isolated [Cu(eta(2)-H-2)Cl]. Comparison with the unstable Na+(H-2) adducts formed in the parent Na-ZSM-5 zeolite allow the conclusion that the Cu(I)/H-2 bond is governed by sigma - pi overlap forces.