Complexes decomposition

As a result the research emphasis in this field focused on efforts to design experiments in which it might be possible to determine to which one of the foregoing three rate equations the observed second-order rate coefficient actually corresponded. More specifically, the objective was to observe one and the same system first under conditions in which complex decomposition (fcp) was rate-determining and then under conditions in which complex formation (kF) was ratedetermining. A system in which either formation or decomposition was subject to some form of catalysis was thus indicated. In displacements with primary and secondary amines the transformation of reactants to products necessarily involves the transfer of a proton at some stage of the reaction. Such reactions are potential-... 

Analogous to the reaction of ()(1 D) + H2, the interaction of the divalent S(4D) atom with 112 molecule leads to the reaction complex of I l2S on the ground PES through the insertion mechanism, in contrast to the 121.6-nm photolysis of H2S on the excited PES. The reaction products are formed via a subsequent complex decomposition to SI l(X2l I) + H. The well-depth of reaction complex H2S, 118 kcal/mol is greater than I l20, 90 kcal/mol as referenced to their product channels. The exoergicity for S + H2, however, is 6-7 kcal/mol, substantially smaller than that for O + H2, 43kcal/mol. 

Aqueous solutions of [Fe(dapsox)(H20)2]C104 in the pH range 1-12 exhibit a reversible redox wave for the Fe /Fe couple, and no complex decomposition or dimerization was observed (46). Furthermore, in the pH range 1-10 the metal-centered redox potential for [Fe(dapsox)(H20)2]C104 is in the range required for the possible SOD... 

There are many examples of first-order reactions dissociation from a complex, decompositions, isomerizations, etc. The decomposition of gaseous nitrogen pentoxide (2N2O5 4NO2 + O2) was determined to be first order ( d[N205]/dt = k[N205j) as is the release of product from an enzyme-product complex (EP E -t P). In a single-substrate, enzyme-catalyzed reaction in which the substrate concentration is much less than the Michaelis constant (i.e., [S] K ) the reaction is said to be first-order since the Michaelis-Menten equation reduces to... 

In some cases the equilibration rate is very slow compared to the time scale of the analytical separation. The pre-equilibrated reaction mixture behaves indeed as a mixture of inert components and can be separated by capillary electrophoresis. The concentrations are directly derived from the peak areas or peak heights after calibration. This method is suitable if ligand and substrate are separable and the migration time does not exceed 1% of the half-life of complex decomposition. 

If the reaction proceeds via the free anion, then this anion should be relatively slowly generated (to prevent sudden precipitation). If the reaction is of the complex-decomposition type, then decomposition of the metal complex should similarly occur relatively slowly (see Sec. 2.5 for a description of reaction mechanisms). 

As for the free chalcogenide processes, the complex-decomposition mechanism can occur either by an ion-by-ion (or molecule-by-molecule, since free ions need not be involved directly) pathway, e.g.. 

Probably the least-known aspect of the CD process is what determines the nucle-ation on the substrate and the subsequent film growth. In considering this aspect, we will treat the ion-by-ion and hydroxide cluster mechanisms separately, although there will be many features in common. The principles discussed should be the same for both the free chalcogenide and the complex-decomposition mechanisms. 

The basic features of the ion-by-ion and hydroxide cluster film-forming mechanisms are shown schematically in Figures 2.1 and 2.2, respectively. Film formation involving complex decomposition will proceed in a similar manner (Fig. 2.3 shows this for a molecule-by-molecule deposition). 

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