Cooperating Ligands in Catalysis

Mechanism of the cooperative Si–H bond activation at Ru–S bonds

“…A combined experimental, spectroscopic, crystallographic, and theoretical investigation provided conclusive evidence for a heterolytic Si–H bond activation pathway involving metal–ligand cooperativity. 5 The principal results are summarized as follows:…”

“…In the absence of any externally added Lewis base, heterolytic cleavage of the Si–H bond is also facilitated by cooperative metal–ligand interactions where the ancillary ligand serves as an internal Lewis-basic site and is directly involved in the Si–H bond activation process. 5 In this case, a mechanism following a [2 + 2]-type cycloaddition ( Scheme 1B ) or a σ-bond metathesis ( Scheme 1C ) is generally postulated. 6 In the former scenario, well-defined addition of the Si–H bond across a metal–ligand multiple bond results in the formation of a metal hydride complex in which the silyl group is incorporated ( cf.…”

Mono- and bimetallic amidinate samarium complexes – synthesis, structure, and hydroamination catalysis

“…34,36,42,45 In general, bimetallic catalysts with both metals in well-defined distance to each other can feature cooperative substrate activation, a highly interesting property for the application in efficient catalytic transformations. [50][51][52][53] On the other hand, it is very challenging to obtain similar bimetallic catalysts together with their monometallic reference systems to study these effects in detail.…”

A low-valent dinuclear ruthenium diazadiene complex catalyzes the oxidation of dihydrogen and reversible hydrogenation of quinones

“…Currently, there are three classes of hydrogenases known which either contain a bimetallic core, [Fe,Fe] or [Fe,Ni], or a single Fe center as active sites 3,4. Intensive spectroscopic investigations, including the determination of the structures of several hydrogenases by single-crystal X-ray diffraction methods,6–8 allowed extraction of the essential features needed for activity: (i) redox active metal centers; (ii) an electron reservoir; (iii) a cooperating ligand9–11 participating reversibly in the heterolytic cleavage/formation of H 2 ; and (iv) a free coordination site for substrate binding (see a simplified sketch of the active [Fe,Fe] core at the top of Fig. 1).…”