Intimate mechanism

The specific feature of polymerization as a catalytic reaction is that the composition and structure of the polymer molecule formed show traces of the mechanism of the processes proceeding in the coordination sphere of the transition metal ion to which a growing polymer chain is bound. It offers additional possibilities for studying the intimate mechanism of this heterogeneous catalytic reaction. 

The intimate mechanism of replacement in ds square planar complexes. L. Cattalini, Prog. Inorg. Chem., 1970,13, 263-327 (139). 

As regards intimate mechanism, electron transfer reactions of metal complexes are of two basic types. These have become known as outer-sphere and inner-sphere (see Chapter 4, Volume 2). In principle, an outer-sphere process occurs with substitution-inert reactants whose coordination shells remain intact in... 

Co(Y)CP and Co(HY)Cl react with Fe " " at comparable rates. Comparisons are instructive between this redox reaction and other cation-catalysed chloride-abstraction reactions which occur without simultaneous oxidation-reduction. The intimate mechanisms are likely to be... 

Understanding of PSEs is complicated by a lack of understanding of the intimate mechanisms of electrocatalytic reactions, for example for the ORR and the MOR. Eurther insights into the reaction mechanisms and identification of the ratedetermining steps will help to elucidate PSEs. 

The cycle shown in Scheme 4 is also thought to form the basis of other Pt based C-H functionalization systems (12,18,19). However, the cycle as pictured in Scheme 4 is quite general and the intimate mechanisms of the individual steps (C-H activation (I), oxidation (II), and functionalization (III)) may differ somewhat in each particular system. 

The intimate mechanism by which the single rhodium sites and the neighboring palladium particles interact with benzene to accelerate its reduction to cyclohexadiene remains somewhat obscure. 

Cattalini, L., The Intimate Mechanism of Replacement in d5 Square-Planar... 

It has in general been the objective of many mechanistic studies dealing with inorganic electron-transfer reactions to distinguish between outer- and inner-sphere mechanisms. Along these lines high-pressure kinetic methods and the construction of reaction volume profiles have also been employed to contribute toward a better understanding of the intimate mechanisms involved in such processes. The differentiation between outer- and inner-sphere mechanisms depends... 

A challenging question concerns the feasibility of the application of high-pressure kinetic and thermodynamic techniques in the study of such reactions. Do long-distance electron-transfer processes exhibit a characteristic pressure dependence and to what extent can a volume profile analysis reveal information on the intimate mechanism ... 

The oxygen exchange processes on the aqua oxo and hydroxo oxo species of these complexes proceed by different intimate mechanisms as described below. 

Actual catalysis is a chemical phenomenon, since the intimate mechanisms of catalytic transformations are determined by chemical interaction of reagents with the catalyst, atomic structure, and the energy of formed intermediate active complexes [5], It obviously is the world of molecular chemistry of the interface phenomena, kinetics, and mechanisms of catalytic transformations at a molecular level. 

A traditional explanation of solid friction, which is mainly employed in engineering sciences, is based on plastic deformation.12 Typical surfaces are rough on microscopic length scales, as indicated in Figure 3. As a result, intimate mechanical contact between macroscopic solids occurs only at isolated points, typically at a small fraction of the apparent area of contact. 

Propene can insert in three ways, which are presented in Figure 10.3. For titanium and zirconium the main mechanism is the 1,2 mode of insertion (note that we say insertion, although the intimate mechanism is a migration ). The other two modes are responsible for mistakes in the polymer chain. 

Some obscure facets of this intricate picture have been unveiled by Filippi and Speranza who investigated the stereochemistry and the intimate mechanism of a model solvolytic reaction taking place in an ion-dipole pair in the gaseous phase. ° Adducts (7 )-56 and R)-51 are obtained in the gas phase by association of the relevant chiral alcohols, i.e., (/ )-(- -)-l-phenyl-ethanol ((I )-44) and (/f)-(- -)-l-(pentafiuorophenyl)ethanol K)-55), with the CHs OHJ ion, generated by y-radiolysis of CH3F/H2 0 mixtures (Scheme 24). As mentioned above, the absence of neutral nucleophile molecules, i.e., CH3 OH, in the reaction medium ensures that the 0-labeled ethers 45 and 58 of Scheme 24 arise exclusively from the intracomplex solvolysis of R)-56 and R)-51, respectively. 

Recently, some attempts were nndertaken to uncover the intimate mechanism of cation-radical deprotonation. Thns, the reaction of the 9-methyl-lO-phenylanthracene cation-radical with 2,6-Intidine (a base) was stndied (Ln et al. 2001). The reaction proceeds through two steps that involve the intermediary formation of a cation-radical/base complex before unimolecular proton transfer and separation of prodncts. Based on the value of the kinetic isotope effect observed, it was concluded that extensive proton tnnneling is involved in the proton-transfer reaction. The assumed structure of the intermediate complex involves n bonding between the unshared electron pair on nitrogen of the Intidine base with the electron-deficient n system of the cation-radical. Nonclassical cation-radicals wonld also be interesting reactants for snch a reaction. The cation-radical of the nonclassical natnre are known see Ikeda et al. (2005) and references cited therein. 

The pressure dependence of the exchange rate constant leads to the activation volume, AV, which has become the major tool for the experimental determination of solvent exchange mechanisms (15,17,18). This is mainly due to the direct connection between the sign of AV and the intimate mechanism for solvent exchange. 

Although photochemically induced cleavage of Al—C bonds in the aluminum porphyrin complexes has been exploited in several applications, relatively little is known about the intimate mechanism of this process. Similar reactivity is observed for the organo-gallium and indium porphyrins, and for these elements... 

The different types of coordination modes of carbonate in metal carbonato complexes offer challenges to investigate intimate mechanisms of their formation. The study of the kinetics and mechanisms of the formation and decomposition of such complexes, therefore, continue to be an interesting area of activity as it has a direct bearing on... 

The complexation, proposed by R. K. Brown and coworkers (Refs. 199-207), of either one of the ring-oxygen atoms by aluminum chloride is reproduced here as a simplification. It seems evident that the intimate mechanism does not imply (i) attack by aluminum chloride, and then (ii) reduction by lithium aluminum hydride actually, the mixed hydride is the reactive species (Ref. 210), and its identity depends on the ratio between the Lewis acid and the hydride (see, for instance, Refs. 211 and 212, and references cited therein, for a discussion of the nature of mixed hydrides). 

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