Exchange reactions Involving solvent

The calculation of equilibrium constants for isotope-exchange reactions involving solvent asymmetry, s ich as the reactions... 

It is interesting to note that C-H activation on ruthenium NHC complexes is not limited to intramolecular protons located in the N-sidechain of the carbene, but occurs inter-molecularly as well. Leimer et al. reacted [MesIRuH PCyj] with toluene-dg at ambient temperature and observed a rapid H/D exchange reaction involving the four hydride hydrogen atoms on ruthenium, the methyl protons of the mesityl substituents of the carbene ligand and the deuterium atoms on the meta positions of toluene-dg. The ortho-, para- and methyl-deuterium atoms of the solvent did not participate [145]. 

An effective way of estimating A G and A Gg is to carry out molecular dynamics calculations for the system being studied. In this way, cumbersome quantum-mechanical calculations involving the reacting system in the solvent are avoided. From a qualitative point of view, an atom exchange reaction involving neutral reactants in a non-polar solvent is expected to be faster in the solvent than in the gas phase. This is due to the fact that two neutral species form one species in the transition state. Very few experimental studies have been carried out one example of a reaction which has been studied is... 

In an isotope-exchange reswition involving solvent asymmetry, for example, reactions (5) and (28), the numerical values of e and of K depend on the concentration scale chosen for the scOution-phase species. For example, application of the Nemst equation to the reaction... 

By virtue of the high donor number of the solvent ligand exchange reactions involving replacement of solvent molecules in the coordination shell by weak competitive ligands are unlikely. Manganese(II) bromide is ionized and no... 

Further studies of the [Co(NH3)e(DMSO)] + ion under neutral conditions show that the anation and solvent exchange reactions involve conjugate-base formation and subsequent rapid substitution, probably by reduction to Co. The conjugate-... 

The most effective way to assess empirically the role of solvent reorganisation in electron-transfer reactions is to study self-exchange reactions involving one uncharged partner, in various solvents. Under such conditions the woik term is zero (w, = 0), and the decrease in the solvent dielectric constant should lead to a decrease of AG/ in eq. (16.13), and to a logarithmic dependence of the rates on y = The results presented in Figure 16.4... 

Radioactive molecules can sometimes be formed by the processes normally involved in the separation. Foremost among these are (1) exchange in the solvent prior to chromatography and (2) thermal reaction during sublimation. Both lead to false results the second is easily eliminated, the first is often not. As an illustration of the effect of sublimation, it was found (61) that the yield of W(CO)g separated by vacuum sublimation at 50° C was 63.8%. The same irradiation conditions yielded 51.8% when the samples were first chromatographed and then sublimed. Evidence for similar effects was found in (PhH)2Cr (75), RuCpj (29) and others. Simple dissolution to break up the lattice, followed by evaporation and sublimation is usually considered satisfactory to eliminate thermal recombination of initially correlated pairs of reactants. 

Baker et al, have obtained some kinetic data on the exchange reactions between the 1,10-phenanthroline, 2,2 -dipyridine and 2,2, 2"-tripyridine complexes of Co(III) and Co(ll) in both H2O and D2O solution. The isotopic method ( Co) and separations involving either extraction of Co(II) with organic solvents (n-hexanol-ether or saturated sodium acetate in n-hexanol) or precipitation of Co(III) as Co(phen)3(l3)3 were used. For the 1,10-phenanthroline system, a rate law... 

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