Abstract
The anation kinetics of the protonated dioxotetracyanomolybdate(IV) ion with 1,10-phenanthroline have been studied spectrophotometrically. The effect of the H+ ion, ionic strength and temperature on the reaction rate has been determined; the rate increases with increasing H+ ion concentration, is independent of ionic strength, and increases with temperature. The reaction follows first order kinetics with respect to [Mo(OH)2- (H2O)2(CN)4]2- and is considered to proceed through the formation of a 1,10-phenanthroline-Mo(OH)2- (H2O)2(CN)4M2- complex (outer sphere) which converts into an inner sphere complex. The formation constant (Kn) for the outer sphere complex has been calculated from the kinetic data by two different methods. Anation of Mo(OH)2-(H2O)2(CN)42- is discussed in terms of an associative interchange (Ia) mechanism. The activation parameters have been calculated using the Arrhenius equation. A substitution mechanism is proposed and the rate equation derived: kobs = kKnKa[H+] [phen] /{1 + KnKa[H+] [phen]}.[PUBLICATION ABSTRACT]