and Br−. Thus in this investigation the change of the outer-sphere anions produce observable effects on thermokinetic of isomerization reaction. The kinetic results were in good agreement with those obtained previously by IR spectroscopy (shown inTables 3 and 4). Also negative entropy of isomerization of bothisomers suggests an association mechanism or bond making in the transition states. So, along with the previous study, it can bethought that a seven-coordinate activated complex appears inisomerization of different salts of nitro and nitrito-pentaamminecobalt(III) isomers [19,26,33,39,40].