The rates and mechanism of substitution reactions of nickel(II) acetylacetonato complexes

Article abstract of DOI:10.1021/ic50043a012

Rates of some substitution reactions of nickel(II) acetylacetonato complexes in aqueous solution at 25° have been measured using a stopped-flow technique. Hydrolysis of the bis complex occurs in two steps, the second about 200 times slower than the first. Rates of hydrolysis depend on (H⁺), suggesting that hydrogen ion traps a half-bonded chelate, causing the reaction to go to completion. When nucleophilic reagents are added, rates of hydrolysis are increased. This effect is attributed to rapid replacement of a water molecule in the first coordination sphere of the nickel by the anion prior to hydrolysis, and not to a direct nucleophilic attack on the metal. The results are rather similar to those found earlier for Pd(acac)₂, with which they are compared.