Solvent exchange activation parameters table

A variety of geometries have been established with Co(II). The interconversion of tetrahedral and octahedral species has been studied in nonaqueous solution (Sec. 7.2.4). The low spin, high spin equilibrium observed in a small number of cobalt(Il) complexes is rapidly attained (relaxation times < ns) (Sec. 7.3). The six-coordinated solvated cobalt(ll) species has been established in a number of solvents and kinetic parameters for solvent(S) exchange with Co(S)6 indicate an mechanism (Tables 4.1-4.4). The volumes of activation for Co " complexing with a variety of neutral ligands in aqueous solution are in the range h-4 to + 1 cm mol, reemphasizing an mechanism. 

Table 2 Selected exchange rate constants and activation parameters for solvent and ligand exchange reactions on square-planar Pt complexes...

Table 32 Rates and activation parameters at 298.2 K for the formation of complexes of the [Al(DMSO)e3 ion and for the solvent exchange process (data from ref. 1)...

Kinetics of cyanide exchange at [M(CN)4] " (M = Ni, Pd, Pt, and Au) have been followed by NMR spectroscopy, using enriched samples in D2O solvent. " Table 5.1 gives the rate constants and activation parameters. Only the second-order dependence could be detected, leading to a simple rate law in equation (6). The exceptionally high value for the nickel complex (too high to be measured by NMR spectroscopy) was assigned to the known stability of the five-coordinate species [Ni(CN)5f which may be similar to the intermediate or transition state for this associative process. 

The base hydrolysis of [Cr(dmso)6] has also been studied in aqueous NaOH. 0 exchange between the coordinated DMSO and OH was observed, and the slow step found to be loss of the first DMSO molecule. Base hydrolysis of [M(NH3)5NCSf ions (M = Co, Cr, Rh) has been studied in aqueous organic solvents (EtOH, Me2CO). fcobs = kX[OH] /(l + [OH ]), but with K ascribed to an ion-pair constant and not conjugate-base formation. The activation parameters were determined and the mechanism discussed. Data for the base hydrolysis of [CrX2L] ions (L = 2,3,2- or 3,2,3-tet) were considered previously (Table 6.3), as were results for the base-catalyzed oligomerization of [Cr(H20)6] (Reference 49) and the photolysis of [Cr(phen)3] under basic conditions (Reference 69). 

Table 9 Comparison of rate constants and activation parameters for ligand substitution at nickeKji) with those for solvent exchange (see text)...

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