Kinetics and mechanism of complex formation between beryllium(II) and the 3-nitrosalicylatopentaamminecobalt(III) ion

Abstract

The kinetics of formation and dissociation of the binuclear complex of Be2+ with 3-nitrosalicylatopentaamminecobalt(III) have been investigated in the 20–40 and 25–40 °C ranges (I = 0.3 mol dm −3), respectively. At 25 °C the rate and activation parameters for the formation of the binuclear species are: k f = 26.9 × 102 dm3mol−1s−1, ΔH ≠ = 104 ± 7kJ mol−1 ΔS ≠= 91 ± 22JK−1mor−1.The rate constant, activation enthalpy and activation entropy for the acid-catalysed dissociation of the binuclear species are: 1.25 ± 0.08dm3mol −1 at 25 °C, 53 ± 3kJ mol−1 and - 67 ± 9 J K −1 mol−1, respectively. The formation of the binuclear species is chelation controlled while the dechelation is acid catalysed.