Kinetics of aquation and base hydrolysis of cis bioxaltoammine bis(ethylenediamine) cobalt(III) ion

Abstract

Cis bioxalatoammine bis (ethylenediamine) Co(III) cation has been synthesized and its aquation and base hydrolysis reactions have been investigated in 1.0 M NaCl0₄ medium. In the range of hydrogen ion concentration 0.02-1.O M and temperature 55-70°C, the rate law for the aquation of (en)₂(NH₃) CoC₂0₄H²⁺ is given by CoCl₂ +Licl ⇔ ^K₂ Licocl₃ with k₁ (70°C) = 1.82 (±0.10) × 10^-5sec^-1 ΔH^∗ = 26.9 (±1.6) kcal/mole and ΔS^∗ = -2.4 (±5) e.s.u.: k₂(70°C) = 3.14 (±0.22) × 10^-5sec-1M-1 ΔH^∗ = 24.0 (± 1.7) kcal/mole and ΔS^∗ = -9.7 (±5) e.s.u.: K₁ (70°C) = 3.0(±0.5) × 10^-2M. The alkaline hydrolysis of (en)₂(NH₃)CoC₂0₄+ was studied at [OH-] < 0.1 M and in the temperature range 30-40°C. The rate law was found to be LiCoCl₃ + LiCl ⇔ ^K₂ Li₂CoCl₄with k₂ (30°C) = 2.75(±0.10) × 10^-3sec^-1M^-1, ΔH^∗ = 30.0(± 1 .1) kcal/mole and ΔS^∗ = 28.6(±3.6) e.s.u.