KINETICS OF SPONTANEOUS AND MERCURY(2)-CATALYZED AQUATION AND ISOMERIZATION OF SULFUR-BONDED MONOTHIOCYANATE COMPLEX OF CHROMIUM(3)

The rate of the spontaneous aquation and isomerization of the sulfur-bonded monothiocyanate complex of chromium(III) is given by the rate law -[d(CrSCN2+)]/dr = {(k0a + k01) + (k-1a + k-1i/(H+)} (CrSCN2+). At 25.0°dg in perchloric acid-sodium perchlorate solutions ofionic strength 1.0 A/the rate constants are k0a = 1.7 X 10-5sec-1, fco′ = 4.2 X 10-5 sec-1, k-1a-ia = 2.7 X 10-6 Msec-1, and k-1i = 6.9 X 10-6 Msec-1. The rate of the mercury(Il)-catalyzed aquation and isomerization of the sulfur-bonded monothiocyanate complex of chromium(III) is given by the rate law - [d(CrSCN2+)dt = {(k0a + k0i) + (k-1a + k-1i/(H+j(CrSCN2+)(Hg2+). At 25.0 in perchloric acid-sodium perchlorate solutions of ionic strength 1.0 M the rate constants are k0a = 3.1 X 102 M-1 sec-1fco′ = 2.3 X 102 M-1 sec-1, k-1a = 3.1 X 102 sec-1, and k-1i = 2.3 X 102 sec-1. The activation parameters for the spontaneous and mercury(II)-catalyzed reactions were determined and their mechanisms are discussed. © 1968, American Chemical Society. All rights reserved.