Salt effects on the reactivity for ligand substitution reactions of [Ru(CN) 5 OH 2 ] 3− anion with two naphthalene substituted ligands (nitroso‐R‐salt and α‐nitroso‐β‐naphthol) in presence of Tetrapropylammonium bromide (Pr 4 NBr) and Sodium chloride (NaCl)

The kinetics of the ligand exchange reaction between aquapentacyanoruthenate(II) [Ru(CN) 5 OH 2 ] 3− ion and naphthalene substituted ligands [α‐nitroso‐β‐naphthol (αNβN), and nitroso‐R‐salt (NRS)] has been studied in aqueous salt solutions of sodium chloride (NaCl) or tetrapropylammonium bromide (Pr 4 NBr) salt. The kinetics was monitored spectrophotometrically at 525 nm corresponding to the λ max of reddish‐brown‐colored substituted products, [Ru(CN) 5 (αNβN)] 3− or [Ru(CN) 5 (NRS)] 3− . Increasing the ionic strength of the reaction mixture using NaCl, exerted a negative salt effect on the rate of formation of naphthalene‐substituted products. At the same time, an increment in the concentration of Pr 4 NBr imparted a positive salt effect on the reaction. The observed rate constant ( k obs ) exhibits linear increment with respect to the concentration of NRS or αNβN while remaining invariant with variation in [Ru(CN) 5 OH 2 ] 3− . The computed activation parameters for NRS (∆ H # = 24.55 kJ mol −1 , E a = 27.03 kJ mol −1 , ∆ G # = 87.83 kJ mol −1 , and ∆ S # = – 212.5 J K −1 mol −1 ) and αNβN ((∆ H # = 17.33 kJ mol −1 , E a = 19.81 kJ mol −1 , ∆ G # = 87.87 kJ mol −1 , and ∆ S # = – 236.7 J K −1 mol −1 ) also support the proposed mechanism.