REACTIONS OF COPPER(1) IN PERCHLORATE SOLUTION . KINETICS AND MECHANISMS OF REDUCTION OF COBALT(3) COMPLEXES BY COPPER(1)

Cobalt(III) complexes are reduced by copper(I) in acidic perchlorate solutions according to a mixed second-order rate expression. The rate constants (M-1 sec-1) at 25.0˚, µ = 0.200 M are: Co(NH3)5Br2+, 4.46 ± 0.15 x 105; Co(NH3)5Cl2+, 4.88 ±0.17 x 104; trans cis-Co(en)2Cl2+, >1 X 107 and 2.13 ±0.09 x 104 Co(NH3)5N32+, 1.50 ±0.02 x 103; Co(NH3)5OH2+, 3.8 x 102; Co(NH3)5NCS2+, ca. 1-3; Co(NH3)5F2+, 1.11 ±0.02; trans-Co(NH3)4(OH2)CN2+, 0.47 ±0.01; Co(NH3)5CN2+, 3.3 ±0.2 x 10-3; ROH23+, 1.0 x 10-3; and Co(en)33+, 4 x 10-4. Many of the reactions were studied as functions of temperature, and Co(NH3)5Br2+ and Co(NH3)5Cl2+ were also studied as a function of ionic strength. The reaction mechanisms are discussed, and arguments for an inner-sphere mechanism are advanced. © 1969, American Chemical Society. All rights reserved.