Coordination compounds, homogeneous catalysis

Asymmetric Synthesis by Homogeneous Catalysis Coordination Chemistry History Coordination Organometallic Chemistry Principles Dihydrogen Complexes Related Sigma Complexes Electron Transfer in Coordination Compounds Electron Transfer Reactions Theory Heterogeneous Catalysis by Metals Hydride Complexes of the Transition Metals Euminescence Luminescence Behavior Photochemistry of Organotransition Metal Compounds Photochemistry of Transition Metal Complexes Ruthenium Organometallic Chemistry. 

G. W. ParshaH, Homogeneous Catalysis The applications and Chemistry of Catalysis by Soluble Transition Metal Complexes,Johm. Wiley Sons, Inc., New York, 1980, 240 pp. An excellent treatment of catalysis by coordination compounds. 

The most numerous cases of homogeneous catalysis are by certain ions or metal coordination compounds in aqueous solution and in biochemistry, where enzymes function catalyticaUy. Many ionic effects are known. The hydronium ion and the hydroxyl ion OH" cat-... 

Chiral cyclic esters of phosphonic acid in the synthesis of coordination compounds and homogeneous asymmetric catalysis 99KK83. 

The applications of coordination compounds in catalysis that have been shown are by no means the only important cases. In fact, there are numerous reactions in which homogeneous catalysis forms the basis for a great deal of chemistry. From the examples shown, it should be apparent that this is a vast and rapidly developing field. It is also one that is important from an economic standpoint. Although the basic principles have been described in this chapter, the literature related to catalysis is extensive. For further details and more comprehensive reviews of the literature, consult the references listed. 

The manifold intermediates in homogeneous transition-metal catalysis are certainly metal complexes and therefore show a behaviour like ordinary coordination compounds associations of phosphorus donors open up multifarious additional controls. Both, substrates and P ligands are Lewis bases that we have to consider and that compete at the coordination centers of the metal, leading to competitive, non-competitive or uncompetitive activation or inhibition processes in analogy to the terminology of enzyme chemistry... 

Of particular interest as catalysts are the incompletely coordinated metal chelate compounds, which are sufficiently stabilized by the ligand to be stable in solution at pH values much higher than that at which the aquo metal ion would precipitate as the hydroxide and thus to become unavailable for homogeneous catalysis. Such a metal chelate would be particularly effective as a catalyst for the activation of a substrate which can coordinate to the metal ion in the chelate compound. The interaction of the substrate with the metal ion would increase its reactivity toward nucleophilic reagents such as solvent molecules or hydroxyl ions, in accordance with the following scheme ... 

Pyridylphosphinoalkane ligands are typical chelate-forming compounds, 386, extremely popular in homogenous catalysis when sometimes dearomatization of one, 387, or both arms in the pincer occurs. The chelate function may combine with the bridging mode, 388. In some specific ligands P,C,C-coordination 389 is possible. 

A106. D. V. Sokol skii, ed., Homogeneous Catalysis by Coordination Compounds. Izd. Him, Frunze, 1970. Proceedings of a Conference held in 1969. Volume 3 contains ... 

The catalytic activity of organic 38 and metallo-organic compounds (134) in heterogeneous systems Reactivity of coordinated ligands 21 and homogeneous catalysis (42)... 

The most numerous cases of homogeneous catalysis are by certain ions or metal coordination compounds in aqueous solution and in biochemistry, where enzymes function catalytically. Many ionic effects are known. The hydronium ion H3O and the hydroxyl ion OH catalyze hydrolyses such as those of esters ferrous ion catalyzes the decomposition of hydrogen peroxide decomposition of nitramide is catalyzed by acetate ion. Other instances are inversion of sucrose by HCl, halogenation of acetone by H and OH , hydration of isobutene by acids, hydrolysis of esters by acids, and others. 

Asymmetric Synthesis by Homogeneous Catalysis Metal Vapor Synthesis of Transition Metal Compounds Metathesis Polymerization Processes by Homogeneous Catalysis Oligomerization Polymerization by Homogeneous Catalysis Organic Synthesis Using Metal-mediated Metathesis Reactions Titanium Inorganic Coordination Chemistry. 

Spectrophotometry. The theory of spectra is far advanced. In many cases, compounds can be unambiguously identified by their ultraviolet, visible, or infrared spectra (e.g., see Smith s book [43]). As an example, the double bond of a CO ligand in a complex has a strong characteristic infrared vibration frequency whose exact value depends on the electronic properties of the coordinating metal these, in turn, are affected by the other substituents. In homogeneous catalysis by transition-metal complexes in particular, foremost among them hydrogenation, hydroformylation, and hydrocyanation, spectra have contributed much to the identification of reaction intermediates and thus of pathways. 

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