ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Hydrolytic reactions of Cr(CN)₂(H₂O)₃NO and NO(H₂O)₄Cr-NC-Hg³⁺ catalyzed by acetate and its α-chloro derivatives

J. Labuda, D. I Bustin, and J. Mocák

Department of Analytical Chemistry, Slovak Technical University, 880 37 Bratislava

Abstract: The catalytic effect of acetate and its α-chloro derivs. as components of buffer solns. on the hydrolysis of Cr(CN)₂(H₂O)₃NO  was studied. The obsd. rate of aquation of the first CN ligand is the sum of the contributions of acid hydrolysis and catalytic terms. The magnitude of the catalytic term depends on the concn. of carboxylate anions and H  ions. Acetate anions also increase the rate of decompn. of the binuclear complex NO(H₂O)₄Cr-NC-Hg³⁺, where the reaction rate is independent of the concn. of H⁺ ions. The reactions are pseudo-1st order with respect to the Cr complex. The equil. and rate consts. of the hydrolytic reactions were found and compared with the kinetic parameters of the catalyzed aquation of Cr(CN)(H₂O)₄NO⁺. A reaction scheme is proposed. The dependence of the kinetics of the hydrolysis of the CN ligand on the concn. of H+ ions is attributed to the protonation of the dissocd. CN group. The catalytic effect of the carboxylate is interpreted in terms of outer sphere effects, where the detg. characteristic is the basicity, i.e. the electron donor properties of the carboxylate anion.

Full paper in Portable Document Format: 354a459.pdf

Chemical Papers 35 (4) 459–469 (1981)