Variable-Temperature and -Pressure Kinetic Study of the Complexation of the Beryllium(II) Ion with 2-Amino-2,4,6-cycloheptatrien-l-one in N,N-Dimethylformamide

Abstract

Kinetics of the formation and dissociation reactions of the 1:l complex of the beryllium(II) ion with 2-amino-2,4,6-cycloheptatrien-l-one in N,N-dimethylformamide (DMF) have been investigated spectrophotometrically at various temperatures and pressures. The rate constants at 298.2 K and the activation parameters are as follows: k_f²⁹⁸ = 9.9 mol⁻¹ dm³ s⁻¹, ΔH_f^‡ = 50.4 ± 5.9 kJ mol⁻¹, ΔS_f^‡ = -53 ± 20 J mol⁻¹ K⁻¹ and V_f^‡ = −7.2 ± 3.9 cm³ mol⁻¹ (298.2 K) for the formation and k_d²⁹⁸ = 6.4 s⁻¹, ΔH_d^‡ = 53.7 ± 0.9 kJ mol⁻¹, ΔS_d^† = −49 ± 3 J mol⁻¹ K⁻¹, ΔV_d^‡ = −1.3 ± 1.3 cm³ mol⁻¹ (298.2 K) for the dissociation. These results indicate that the reaction mechanism for the complexation of the beryllium(II) ion in DMF is associative in character. The volume profile for this reaction system is discussed in comparison with that for the related complexation.