Interchange rate constant

Fig. 13. Absolute partial molar volumes, Vab8°, of [Ln(H20) P in aqueous LnCl3 solutions (301) (closed circles), compared with the calculated Vabs° values (4, 42) for [Ln(H20)8]3+ and [Ln(H20)9]3 indicated by the upper and lower solid curves, respectively. Interchange rate constants, kj (298 K) (310), for the substitution of S042 on [Ln(H20) ]3+ are shown as open squares, and water exchange rate constants, fcn2o (298 K) (311, 312), for [Ln(H20)8]3+ are shown as open circles. 

The overall rate const kf is measured by the relaxation methods. Assuming that the outer-sphere complex formation is faster than the water substitution by ligand L, the interchange rate constant k can be calculated using the equation... 

Fig. 7.24. Water exchange rate constant ((O), ref. [41]) and interchange rate constants k from ultrasonic absorption results at 298 K for aqueous Ln3+ ions ( ) SO - (ref. [69]) ( ) acetate (ref. [70]) (A) nitrate...

In reality the complex-formation rate constant is a composite of the precursor complex or ion-pair formation constant (Kq) and the subsequent interchange rate constant (fei), i.e. k = Kok, as shown in Eqs (1.3) and (1.4). 

Fig. 4.6. Absolute partial molar volumes, Interchange rate constants, (ci, for the...

The reaction of Mg + with pyrophosphate is about twice as slow in D2O as in H2O (at 15 °C). This difference is attributed to a change in the outer-sphere association constant rather than to a change in the interchange rate constant. Kinetics of solvolysis of [Fe(bipy)3] + in D2O lend support to the mechanism of dissociation via a unidentate-bipyridyl transient intermediate postulated, for aqueous solution, many years ago. ... 

The dependence of rate constant on ionic strength is still widely used, often in conjunction with the dependence of rate constant on dielectric constant, as an indicator of substitution mechanism. Recent instances of this classical approach include the reaction of /ra j-[Co(dmgH)2(SCN)(tu)] with thiourea (tu), aquation of trans-[Rh(dmgH)2Cl(tu)], aquation of the [Co(02CCHaCl)(NH3)6]"+ cation, and substitution at the [Fe(CN)6(OH2)] anion by nitrite, thiocyanate, sulphite, or nitrosobenzene. Salt effects on observed rate constants for the reaction of nickel(n) with pyrophosphate operate via the outer-sphere association constant rather than via the interchange rate constant. ... 

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