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 both isomers 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].