The base of hydrolysis of
[(tetren)CoO
2
CR]
2+
{R=NH
2
CH
2
—,
NH
2
[CH
2
]
2
—, pyridine-2-
(αβS isomer),
NH
2
CH(CH
3
)— (αβS
and αβR isomers);
tetren=tetraethylenepentamine} is accelerated by
acetonitrile+water media (0≤X
AN
≤0.578,
X
AN
=mole fraction of acetonitrile) owing to
the combined effects of destabilisation of OH
-
,
relatively greater destabilisation of the transition state of the
amido conjugate base
[((tetren)-H)Co
2+
-
O
2
CR]
+
* as compared to that of the initial state
[(tetren)CoO
2
CR]
2+
, and solvent structure;
the activation enthalpies and entropies are also sensitive to
solvent structure and conformational arrangement of the tetren
ligand.