Original scientific paper

Kinetics and Mechanism of Base Hydrolysis of (Dimethyl Sulphoxide)Penta-Amminecobalt(III) Ions

M. Biruš ; Department of Chemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb
W. L. Reynolds ; Department of Chemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb
M. Pribanić ; Department of Chemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb
S . Ašperger ; Department of Chemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb

Abstract

Data are presented showing that at constant 0.02 M OH- the
rate of the base hydrolysis of the (NH3)5 Co(DMS0)3+ ion increases
with an ·increase in the nonaqueous component in aqueous-organic
mixtures containing methanol, ethanol, DMSO ( = dimethyl suiphoxide),
acetone or dioxane. The enhancement in the rate, which
amounts to more than 100 fold in organic component-rich mixtures,
is discussed in terms of an increase of the basicity of the mixed
solvents due to the decreasing salvation of OH-. The base hydrolysis
of the DMSO-complex ion in the presence of 1 M anion Y and
0.125 M Off yields 12.8, 9.9, 7.8, 1.8, and 3.7 mol 0/o (NHs); CoY from
(NH3); CoX for the competing anions Ns-, ScN-, N02-, OAc-, and
S04 2-, respectively. The mechanistic implications of these results are
discussed in terms of SNlCB and Id mechanisms.

Keywords

Hrčak ID:

196576

URI

https://hrcak.srce.hr/196576

Publication date:

16.2.1976.

Visits: 545 *