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, H = 104 ± 7kJ mol^-1 S = 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.