Reactions in micellar solutions: Part 7-Micellar effects on acid, base and metal ion catalysed hydrolysis of cis-(diformato)bis-(ethylenediamine)cobalt(III)

Abstract

The kinetics of acid, base and metal ion (Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) catalysed hydrolysis of <em>cis- </em>(diformato) bis(ethylenediamine)cobalt(III) have been investigated in the presence of neutral (Triton-X 100) and anionic surfactant (sodium dodecyl sulphate, SDS). The rate acceleration by neutral micelles of the base hydrolysis reaction and the acid and metal ion catalysed aquation is but marginal. The anionic micelles of SDS also retard the base hydrolysis reaction to a small extent but strongly favour the formation of the protonated species, <em>cis-</em>[Co(en)₂{H(O₂CH)₂}]²⁺ and the binuclear species, <em>cis</em>-[Co(en)₂{M(O₂CH)₂}]³⁺ which accelerate the rates of H⁺ and M²⁺ catalysed aquation. The reactivities of the binuclear species in the micellar pseudo-phase of SDS follow the Irving-Williams order: Co(II) &lt; Ni(II) &lt; Cu(II) &gt; Zn(II).