Ruthenium Catalysts for the Kharasch Reaction
Recent advances in the development of ruthenium catalysts for the atom transfer radical addn. of polyhalogenated compds. to olefins ('Kharasch reaction') are described. Three classes of homogeneous catalysts are discussed: halfsandwich complexes with h6-arene, h5-cyclopentadienyl or h5-carborane ligands, ruthenium complexes with alkylidene- or vinylidene ligands and polynuclear complexes. Furthermore, first attempts to use immobilized ruthenium complexes as heterogeneous catalysts for the Kharasch reaction are summarized.