Multimetallic Catalysis Based on Heterometallic Complexes and Clusters

Trivalent Lewis Acidic Cations Govern the Electronic Properties and Stability of Heterobimetallic Complexes of Nickel

“…[1,2] The presence of multiple metal centers can give rise to synergistic properties, including improved substrate binding, [3] enhanced rates of catalysis, and unique stability. [4] These features contributet ot he high activity of multimetallic active sites in enzymes that catalyze complex reactions,f or example N 2 fixation by nitrogenase [5] or O 2 reduction by cytochrome c oxidase.…”

“…Notably,t he Lewis acidities of Y 3 + and other trivalent ions are significantly greatert han other ions such as Ca 2 + or Sr 2 + ;c onsequently, there is ap rivileged position for Y 3 + and Sc 3 + in modulating the reactivityo ft he iron complexes described above. [19] However,d espite the relevance of these heterometallic effects to possible applicationsi nc atalysis [2] and energy science, [22] chemical preparation of compounds that contain trivalent Lewis-acidic ions with at ransition metal has received less attentiont han it deserves.T sui et al and Herbert et al have quantified Lewis acidity effects in multimetallic manganese [23] and iron [24] oxo-bridged clusters, respectively.T hey find ad istinctive shift in reduction potential of their clusters as af unction of the Lewis acidity of ab ound redox-inactivem etal,i ncluding the trivalent rare-earth cations Y 3 + and Nd 3 + . One possible strategy for preparation of heterobimetallic complexes involves synthesis of ditopic frameworks with binding motifs that display distinct ligand properties and that can therefore facilitate orthogonal metallations.…”

High Catalytic Activity of Heterometallic (Fe₆Na₇and Fe₆Na₆) Cage Silsesquioxanes in Oxidations with Peroxides

“…First of all, the use of different metal ions is known as a key to controlled design of high-nuclearity complexes of picturesque molecular architecture [1][2][3][4][5]. Also, acting together, different metal ions provide catalytic activity in a wide range of processes [6][7][8] as well as intriguing magnetic properties [9]. The most popular synthetic approaches to such complexes involve use of organic ligands as well as application of "complex-as-ligand" tactics [10][11][12][13].…”

The Chemical Record—A Historical Commentary

“…Indeed, numerous examples of enhanced catalytic activity or selectivity for (intact or not) metal clusters, particularly heterometallic ones, have been reported and this research topic remains very active. [14] But looking at the metal core of these metal clusters, and of larger ones prepared in other laboratories, my feeling was that using them as precursors to nanoparticles for heterogeneous catalysis might be more promising. If thermal activation of a cluster adsorbed on an inorganic support (alumina, silica, etc.)…”

“…[17] The concept of mixed-metal clusterderived heterogeneous catalysts has since been increasingly used by the scientific community and hundreds of examples are now available. [14] There are two more lessons to learn from this second story. First, innovative ideas may require time and much effort to materialize and be developed, but the rewards provide satisfaction and encouragement.…”