KINETICS AND MECHANISM OF COMPLEX-FORMATION REACTIONS OF AMMONIA AND METHYLAMINE WITH COPPER(II) COMPLEXES IN AQUEOUS-SOLUTION

The complex-formation kinetics of copper(II) complexes with ammonia and methylamine was investigated by the temperature-jump relaxation technique. At 2 mol dm-3 ionic strength the forward rate constants (dM3 mol-1 s-1) for the studied reactions are: [Cu(NH3)]2+ + NH3 half arrow right over half arrow left [Cu(NH3)2]2+, (1.2 +/- 0.1) x 10(8) (7-degrees-C); [Cu(ida)] + NH3 half arrow right over half arrow left [Cu(ida)(NH3)], (3.7 +/- 0.3) x 10(8); [Cu(ida)]+ NMeH2 half arrow right over half arrow left [Cu(ida)(NMeH2)], (8.7 +/- 0.3) x 10(7); [Cu(mida)] + NMeH2 half arrow right over half arrow left [Cu(mida)(NMeH2)], (5.4 +/- 0.3) x 10(7) (25-degrees-C); ida = iminodiacetate, mida = N-methyliminodiacetate. The results presented and those from previous literature strongly suggest that specific interactions between the co-ordinated groups and the central metal ion do not modify the kinetics and mechanism of the complex formation. The kinetic data are consistent with the Eigen-Wilkins mechanism.