The combination of the air-stable RuIII complex [Cp*RuCl2(PPh3)] with AIBN can be used to catalyze the atom transfer radical addition reactions of polychlorinated compounds and of sulfonyl chlorides to olefins with unprecedented turnover numbers of up to 44 000.

A bimetallic complex, in which a RuCl2(η2-C2H4)(PCy3) fragment is connected via three chloro bridges to a (η6-p-cymene)RuCl2 fragment, has been synthesized and characterized by single-crystal X-ray crystallography. This complex was used to catalyze the atom transfer radical addition of CCl4 and CHCl3 to olefins at temperatures between 0 and 40 °C. Turnover frequencies of up to 1550 h-1 were observed, making the new complex one of the most active catalysts for this type of reaction described so far.

A radical alternative? Two highly efficient catalysts for atom‐transfer radical additions were discovered in a parallel screening of bimetallic complexes. Both catalysts contain a rhodium‐centered fragment (blue), which is connected through three chloro bridges to a ruthenium‐centered fragment (red).

Simply mixing the complex [{RuCl2(1,3,5‐C6H3iPr3)}2] (1) with PCy3 is sufficient to generate a catalyst suitable for highly efficient atom‐transfer radical addition and polymerization reactions at exceptionally low temperatures (see scheme). The steric congestion at the metal caused by the bulky ligands is thought to be essential for the reactivity of the catalyst.

Methods for the synthesis of bimetallic complexes in which two different metal fragments are connected by three chloro or bromo bridges are reported. The reactions are general, fast, and give rise to structurally defined products in quantitative yields. Therefore, they are ideally suited for generating a library of homo- and heterobimetallic complexes in a combinatorial fashion. This is of special interest for applications in homogeneous catalysis. Selected members of this library were synthesized and comprehensively characterized; single-crystal X-ray analyses were performed for 15 new bimetallic compounds.