axial ligands and characterized the mononuclear S= 1/2 H2 adduct complex (SiP i Pr3) FeI
(H2). EPR and ENDOR data, in the context of X-ray structural results, revealed that this
complex provides a highly unusual example of an open-shell metal complex that binds
dihydrogen as a ligand. The H2 ligand at 2 K dynamically reorients within the ligand-binding
pocket, tunneling among the energy minima created by strong interactions with the three Fe …