Observation of exceptionally strong binding of molecular hydrogen in a porous material:: Formation of an η2-H2 complex in a Cu-exchanged ZSM-5 zeolite

We have measured the rotational tunneling spectrum of a Cu-ZSM-5 zeolite after loading with H-2, by means of inelastic incoherent neutron scattering. The peaks at +/- 0.80 and +/- 1.73 cm(-1) unambiguously demonstrate the formation of a strongly bound Cu(eta(2)-H-2) complex.