Photochemistry of Alkyltransition‐Metal Complexes

Alkyltransition‐metal complexes play an important role in catalytic processes (e.g. Ziegler‐Natta low‐pressure polymerization, hydroformylation, Fischer‐Tropsch synthesis), in the biochemistry of humans and animals (e.g. coenzyme B 12 ), and in the classical theory of the chemical bond (e.g. multicenter bonding). The chemistry of alkyltransition‐metal complexes is 30 years old, but only with the '70s came the understanding necessary for the systematic synthesis of thermally stable representatives of this class of compounds by blocking preferred decomposition pathways—e.g. β‐hydrogen elimination—by the introduction of suitable ligands. In this article it is shown that thermally stable alkyltransition‐metal complexes can be dealkylated under mild conditions (even at 12 K) with the help of UV light, thus producing highly reactive intermediates which can be trapped and used preparatively. Some alkyl complexes which do not react thermally with unsaturated compounds, e.g. olefins, under the influence of UV light display high activity as polymerization catalysts.