Elementary Steps of Catalysis

Ions can be accelerated and decelerated by electric field in high vacuum. When charged molecules ions are collided with rare gases at high velocity, they fragment. While some molecules simply fall apart, some rearrange before they split. When the energy of the colliding ions is controlled, it is possible to extract thermochemical information from the intensity of the fragments.

Transition metal complexes are known to catalyse a wide range of reactions. They are often charged and are hence well suited for our methodology. Simple dissociations from a metal centre can be measured straightforwardly and are relevant, because all catalytic cycle at least involve decoordination of product or coordination (the microscopic reverese of a dissociation) of reactant.

It is also possible to obtain information on elementary reactions that do not involve a change in mass, when they are followed by a dissociation. The concept is illustrated on a general reductive elimination shown below. For the measurement to tell something about the bond-​forming step, the subsequent dissociation needs to be faster than the first step.