Bound-Ligand Effect in the Complexation Kinetics of Hydroxozirconium(IV) and Hydroxohafnium(IV) Complexes

Shinkichi YAMADA; Ichirou YAMAUCHI; Akira MURATA

doi:10.2116/analsci.11.903

Shinkichi YAMADA, Ichirou YAMAUCHI, Akira MURATA

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Keywords: Zirconium, hafnium, Semixylenol Orange, complexation kinetics, bound ligand effect

JOURNAL FREE ACCESS

1995 Volume 11 Issue 6 Pages 903-908

DOI https://doi.org/10.2116/analsci.11.903

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Published: December 10, 1995 Received: July 19, 1995 Available on J-STAGE: July 04, 2006 Accepted: October 05, 1995 Advance online publication: - Revised: -
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Date of correction: July 04, 2006 Reason for correction: - Correction: ABSTRACT Details: Wrong : The kinetics of the complexation reaction of zirconium(IV) and hafnium(IV) with Semixylenol Orange (H₄L) have been studied spectrophotometrically by means of a stopped-flow technique. The rate of formation of the complex is expressed as d[MHL⁺]/dt=k₁[M⁴⁺][H₅L⁺][H⁺]^-2+k₂[M⁴⁺][H₅L⁺][H⁺]^-3-k₃[MHL⁺][H⁺]-k₄[MHL⁺][H⁺]² for both metal ions (M⁴⁺). With values of k₁ and k₂, assuming a dissociative interchange mechanism for the first two reaction paths in this rate equation, the rate constants of the loss of coordinated water molecules at MOH³⁺ and M(OH)₂²⁺ were estimated. With these rate constants, the γ parameters for both metal ions, which describe the acceleration effect of the bound ligand A (A=OH- in this study) on the water exchange rate at MA, were also estimated. With the same parameter, some possibilities to design a new kinetic-catalytic method of analysis based on ligand-substitution reactions involving zirconium(IV) were proposed.
Right : The kinetics of the complexation reaction of zirconium(IV) and hafnium(IV) with Semixylenol Orange (H₄L) have been studied spectrophotometrically by means of a stopped-flow technique. The rate of formation of the complex is expressed as d[MHL⁺]/dt=k₁[M⁴⁺][H₅L⁺][H⁺]^-2+k₂[M⁴⁺][H₅L⁺][H⁺]^-3-k₃[MHL⁺][H⁺]-k₄[MHL⁺][H⁺]² for both metal ions (M⁴⁺). With values of k₁ and k₂, assuming a dissociative interchange mechanism for the first two reaction paths in this rate equation, the rate constants of the loss of coordinated water molecules at MOH³⁺ and M(OH)₂²⁺ were estimated. With these rate constants, the γ parameters for both metal ions, which describe the acceleration effect of the bound ligand A (A=OH^- in this study) on the water exchange rate at MA, were also estimated. With the same parameter, some possibilities to design a new kinetic-catalytic method of analysis based on ligand-substitution reactions involving zirconium(IV) were proposed.

Date of correction: July 04, 2006 Reason for correction: - Correction: PDF FILE Details: -

Abstract

The kinetics of the complexation reaction of zirconium(IV) and hafnium(IV) with Semixylenol Orange (H₄L) have been studied spectrophotometrically by means of a stopped-flow technique. The rate of formation of the complex is expressed as d[MHL⁺]/dt=k₁[M⁴⁺][H₅L⁺][H⁺]^-2+k₂[M⁴⁺][H₅L⁺][H⁺]^-3-k₃[MHL⁺][H⁺]-k₄[MHL⁺][H⁺]² for both metal ions (M⁴⁺). With values of k₁ and k₂, assuming a dissociative interchange mechanism for the first two reaction paths in this rate equation, the rate constants of the loss of coordinated water molecules at MOH³⁺ and M(OH)₂²⁺ were estimated. With these rate constants, the γ parameters for both metal ions, which describe the acceleration effect of the bound ligand A (A=OH^- in this study) on the water exchange rate at MA, were also estimated. With the same parameter, some possibilities to design a new kinetic-catalytic method of analysis based on ligand-substitution reactions involving zirconium(IV) were proposed.

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