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Metal-ligand Cooperativity
Metal-ligand cooperativity (MLC) is a mode of reactivity in which a metal and ligand of a complex are both involved in the bond breaking or bond formation of a substrate during the course of a reaction. This ligand is an actor ligand rather than a Spectator ligand, spectator, and the reaction is generally only deemed to contain MLC if the actor ligand is doing more than leaving to provide an open coordination site. MLC is also referred to as "metal-ligand bifunctional catalysis." Note that MLC is not to be confused with cooperative binding. The earliest reported metal-ligand cooperativity was from the Fujiwara group in the 1950s, in which they reported formation of stilbene from styrene and arenes using a palladium chloride catalyst. Shvo catalyst, Shvo's catalyst was developed for one of the earliest uses of ketone hydrogenation by an Outer sphere electron transfer, outer-sphere mechanism. Ryōji Noyori, Noyori has developed many chiral catalysts for asymmetric hydrogenation. Transf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectator Ligand
In coordination chemistry, a spectator ligand is a ligand that does not participate in chemical reactions of the complex. Instead, spectator ligands (vs "actor ligands") occupy coordination sites. Spectator ligands tend to be of polydentate, such that the M-spectator ensemble is inert kinetically. Although they do not participate in reactions of the metal, spectator ligands influence the reactivity of the metal center to which they are bound. These ligands are sometimes referred to as ancillary ligands. Several different classes of ligand exist that can be considered spectator ligands. A few examples include trispyrazolylborates (Tp), cyclopentadienyl ligands (Cp), and many chelating diphosphines such as 1,2-bis(diphenylphosphino)ethane ligands (dppe). Varying the substituents on the spectator ligands greatly influences the solubility, stability, electronic, and steric properties of the metal complex. In the area of platinum-based antineoplastic agents, spectator (and nonspectator ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
