Metal ion catalysed aquation of carboxylatoamine cobalt(III) complexes. Kinetics of copper(II) catalysed aquation ofcis(diformato)bis(ethylenediamine)cobalt(III) ion

The aquation of cis-[(en)<SUB>2</SUB>Co(CO<SUB>2</SUB>H)<SUB>2</SUB>]<SUP>+</SUP> to cis-[(en)<SUB>2</SUB>Co(OH<SUB>2</SUB>)(CO<SUB>2</SUB>H)]<SUP>2+</SUP> is catalysed by Cu<SUP>2+</SUP> and the rate equation, -d[complex]<SUB>T</SUB>/dt=(k<SUB>Cu</SUB>[Cu<SUP>2+</SUP>]+k<SUB>H</SUB> [H<SUP>+</SUP>]) [complex)<SUB>T</SUB> is valid at [Cu<SUP>2+</SUP>]<SUB>T</SUB>=0.01-0.1, I = 0.5 and [HClO<SUB>4</SUB>] = 0.005 mol dm<SUP>-3</SUP>. The rate measurements are reported at 30, 35, 40 and 45&#176;C and the rate and activation parameters for the Cu<SUP>2+</SUP> and H<SUP>+</SUP>-catalysed paths are: k<SUB>H</SUB>(35&#176;C) = (2.44&#177;0.09) &#215; 10<SUP>-2</SUP> dm<SUP>3</SUP> mol<SUP>-1</SUP> s<SUP>-1</SUP>, &#916;H<SUP>&#x2021;</SUP> = 83&#177; 13 kJ mol<SUP>-1</SUP>, &#916;S<SUP>&#x2021;</SUP>= -8&#177;42 JK<SUP>-1</SUP> mol<SUP>-1</SUP>, k&#39;<SUB>Cu</SUB>(35&#176;C) = (3.30&#177;0.09) &#215; 10<SUP>-3</SUP> dm <SUP>3</SUP> mol<SUP>-1</SUP> <SUP>-1</SUP>, &#916;H&#x2021;=73.2&#177;6.1 kJ mol<SUP>-1</SUP>, &#916;S<SUP>&#x2021;</SUP>=-55&#177;20 JK<SUP>-1</SUP> mol<SUP>-1</SUP>. The formate-bridged innersphere binuclear complex,cis-[(en)<SUB>2</SUB>Co{(O<SUB>2</SUB>CH)<SUB>2</SUB>Cu}]<SUP>3+</SUP> may be involved as the catalytically active intermediate in the copper(II)-catalysed path, just as the corresponding H<SUP>+</SUP>-bridged species presumed to be present in the acidcatalysed path