The importance of the interaction of hydrogen with transition metals has
been well established for both stoichiometric and catalytic reactions in organometallic
chemistry. Molecular hydrogen, H2, interacts with an active transition
metal complex, causing rupture of the H-H bond and the eventual formation of
a mono- or dihydride complex, which may undergo further reactions. Elucidation
of the mechanism and investigation of the hydride products and intermediates
is an important aspect of the study of hydrogenation reactions