INTERACTION OF 1-CYSTEINE WITH HYDROXOPENTAAQUARHODIUM(III) ION - KINETIC AND MECHANISTIC STUDIES

The interaction of 1-cysteine with hydroxopenta-aquarhodium(III) has b een studied spectrophotometrically as a function of pH, [entering liga nd], [substrate] and temperature following the absorption of l-cystein e substituted product at 352 nm. The reaction rate increases with incr ease in [ligand] and approaches a limiting rate. The values of Delta H -not equal (72.6+/-0.6 kJ) and Delta S-not equal (-91.0 +/- 1.8 JK(-1) mol(-1)) have been calculated from Eyring plot and compared with aqua exchange and analogous ligand substitution processes. An associative interchange mechanism with the ligand participation in the TS is propo sed.