Stability constants of Al(III) complexes in aqueous solution obtained from kinetic measurements

Abstract

Many aluminium complexes are formed from the aquo-metal ion in the time range 0.01 to 100 s. Therefore, this process can be conveniently studied by stopped-flow techniques. Complex formation is associated with a change in the electrical conductivity of the solutions and the stability constants have been evaluated from the size of this change. Either the inner-sphere stability constant, K i, or the overall association constant, K a, can be determined. The following values have been obtained: for AlSO + 4, p K i = 0.78±0.10; for AlFe(CN) 6 and AlCo(CN) 6 p K i = 0.89±0.10; for HCOOAl 2+, p K i = −0.76±0.10; p K a = −2.10±0.07; and for H 2CitAl 2+, p K a = − 2.62±0.10.