
TY  - JOUR
A1  - Lawrance, GA 
A1  - Hay, RW 
T1  - Kinetics of aquation and base hydrolysis of the macrocyclic complex <I>trans</I>-Bromo(N-<I>meso</I>-5,12-dimethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene)nitro-cobalt(III) perchlorate
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1976
VL  - 29
IS  - 10
SP  - 2319
EP  - 2324
KW  - 
UR  - https://doi.org/10.1071/CH9762319 
N2  - The macrocyclic complex trans-[Co(dtcd)(NO2)Br] [ClO4] (dtcd = 5,12-dimethyl-l,4,8,1l-tetraaza-cyclotetradeca-4,ll-diene) has been prepared and its hydrolysis kinetics investigated. At 25ºC and 0.1 M HN03 the aquation occurs with kaq = 6.2 x 10-3 s-1 to give the trans-Co(dtcd)(NO2)- (OH2)]2+ cation. The activation parameters at 298 K are &#916;H? = 75.0 kJ mol-1 and &#916;S? = -35.6 J K-1 mol-1. Hydrolysis of the bromide in the pH range 7.5-8.8 follows the rate expression kobs = kaq + kOH[OH-]. At 25ºC (I = 0.1 M, NaClO4) kOH = 1.21 x 103 1. mol-1 s-1 with the activation parameters for base hydrolysis being &#916;H? = 74.2 kJ mol-1 and &#916;S? = +63.2 J K-1 mol-1 at 298 K. Aquation and base hydrolysis of the bromo complex at 25ºC occur at rates 14 and 5 times faster respectively than those previously reported for the analogous trans-[Co(dtcd)(NO2)Cl]+ complex, the acceleration being due to a more favourable entropy of activation in each case. 
ER  -

