Taube mechanism

F. Y. Hansen, L. W. Bruch and H. Taub, Mechanism of Melting in Submonolayer Films of Nitrogen Molecules Adsorbed on the Basal Plane of Graphite, Phys. Rev. B 52 (1995) 8515-8527 Y. P. Joshi and D. J. Tildesley, A Simulation Study of the Melting of Patches of N2 Adsorbed on Graphite, Mol. Phys. 55(1985) 999-1016. 

H. Taube (Stanford) mechanisms of electron transfer reactions of metal complexes. 

Mechanisms of redox reactions in simple chemistry. H. Taube, Adv. Inorg. Chem. Radiochem.,... 

In the same way that we considered two limiting extremes for ligand substitution reactions, so may we distinguish two types of reaction pathway for electron transfer (or redox) reactions, as first put forth by Taube. For redox reactions, the distinction between the two mechanisms is more clearly defined, there being no continuum of reactions which follow pathways intermediate between the extremes. In one pathway, there is no covalently linked intermediate and the electron just hops from one center to the next. This is described as the outer-sphere mechanism (Fig. 9-4). 

Mechanisms of Redox Reactions of Simple Chemistry H. Taube... 

The latter reaction must involve a large number of molecular steps and may be a much slower process. The mechanisms of a few inorganic electron transfer processes have been summarized by Taube (1968). The presence of very slow reactions when several redox couples are possible means that the Eh value measured with an instrument may not be related in a simple way to the concentrations of species present, and different redox couples may not be in equilibrium with one another. Lindberg and Runnells (1984) have presented data on the extent of disequilibrium... 

Taube, H. (1968). Mechanisms of oxidation-reduction reactions. /. Chem. Educ. 45,453-461. 

The last two decades have seen a growing interest in the mechanism of inorganic reactions in solution. Nowhere is this activity more evident than in the topic covered by this review the oxidation-reduction processes of metal complexes. This subject has been reviewed a number of times previously, notably by Taube (1959), Halpern (1961), Sutin (1966), and Sykes (1967). Other articles and books concerned, wholly or partly, with the topic include those by Stranks, Fraser , Strehlow, Reynolds and Lumry , Basolo and Pearson, and Candlin et al ° Important recent articles on the theoretical aspects are those by Marcus and Ruff. Elementary accounts of redox reactions are included in the books by Edwards , Sykes and Benson . The object of the present review is to provide a more detailed survey of the experimental work than has hitherto been available. 

Endicott and Taube consider that there is cause for doubt over the generally-held views that Cr(bipy)3 is oxidised by an outer-sphere mechanism"". They suggest that, since the complex is very labile to substitution, coordination sites... 

It is salutary to read the comment, At the time when I became interested in the reactions of coordination compounds the formula of not a single aquo complex was known with certainty, made by Taube in a recent review (364). In marked contrast, this review is predominantly concerned with the intimate detail of the mechanisms of sol-... 

The interaction between experiment and theory is very important in the field of chemical transformations. In 1981 Kenichi Fukui and Roald Hoffmann received a Nobel Prize for their theoretical work on the electronic basis of reaction mechanisms for a number of important reaction types. Theory has also been influential in guiding experimental work toward demonstrating the mechanisms of one of the simplest classes of reactions, electron transfer (movement of an electron from one place to another). Henry Taube received a Nobel prize in 1983 for his studies of electron transfer in inorganic chemistry, and Rudolf Marcus received a Nobel Prize in 1992 for his theoretical work in this area. The state of development of chemical reaction theory is now sufficiently advanced that it can begin to guide the invention of new transformations by synthetic chemists. 

Several experimental facts have been rationalized in terms of different n-allyl insertion mechanisms, depending on the nature of the catalytic systems and the diene monomer, mainly by the extensive work of Porri and co-workers, as reviewed in Refs. 181 and 182, and Taube and co-workers, as reviewed in Ref. 183. A widely accepted scheme for cis-1,4 and 1,2 polymerizations of conjugated dienes is reported in Scheme 1.5. In particular, it has been... 

According to Taube, the inner sphere mechanism can takes place when both oxidizing and reducing agents are substitution inert and when ligand transfer from oxidant to reductant is accompanied by electron transfer. The inner sphere electron transfer mechanism may be represented by the scheme... 

A similar mechanism was proposed earlier by Adamson for photoreduction of Co(NH3)5Br2 +. 48 An observed 4>red of 1.97 for Co(NH3)5I2+ predicts a quantum efficiency of 0.97 for the primary process [reaction (20)]. The mechanism also predicts that 4>red will depend upon the Co(NH3)5I2+ concentration and inversely upon the intensity of the irradiating light in the case where recombination of I atoms is important. Support for the mechanism of Haim and Taube came from the observation that upon flash photolysis of Co(NH3)5I2 + solutions with 370-mp. light, unusually short-lived transient I atoms were observed.62 This was taken to indicate that paths [reaction (21), for example] other than I atom recombination accounted for loss of I atoms in this system. 

H. Taube, Electron Transfer Reactions of Complex Ions in Solution, Academic Press, New York 1970. >C.K. Ingold, Structure and Mechanism in Organic Chemistry, 2. Aufl. S. 406-417, Cornell University... 

In 1958, as I remember it, Fred Basolo and I, Arthur Adamson and Henry Taube, and H. R. Hunt came out with this mechanism basically, stressing slightly different features. Then Dr. Tobe joined the bandwagon with this mechanism in 1959, and the term solvent assisted dissociation was coined by Wallace and his group in Canada in 1961. That is the story as I see it at the present time... 

This is the optical density plotted against the time for an experiment in which we took the nitratopentamminecobalt complex in the presence of 0.50M thiocyanate ion since the competition ratio for thiocyanate ion and for water had been determined by Haim and Taube. Knowing the optical densities of all the possible reactants and products, we could calculate what the optical density should be as a function of time according to the mechanism of Haim and Taube. This calculation depends upon a rate constant for the aquation of the nitrato complex which we took from the literature. But one should get a continuously increasing optical density because the thiocyanate complex has a higher optical density than anything else. 

The experimental points here follow the predictions of the second mechanism very closely, and I would say that not more than 2% of thiocyanate complex is formed directly. Taube and Haim s prediction would be 14%. 

We have done the same experiment, incidentally, for the bromopentammine and the results are precisely the same. You will recall that Langford mentioned that also in the hydrolysis of the chloropentammine there was no mass law retardation such as would be predicted from the mechanism of Haim and Taube. 

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