Kinetics of ternary complex formation between NiII species and pyridine-2-azo-p-dimethylaniline at high pressure, by a laser temperature-jump method

Abstract

The kinetics of the reaction of the ligand pyridine-2-azo-dimethylaniline (pada) with NiL^II species [L = ethylenediaminediacetate (edda), nitrilotriacetate (nta), diethylenetriamine (dien), triethylenetetramine (trien), 2, 2′, 2″-triaminotriethylamine (tren)] has been studied at pressures up to 3 000 bar.‡ Volumes of activation and reaction are reported. The volumes of activation fall into two groups: +3 cm³ mol^–1(L = tren, trien); +6 cm³ mol^–1(L = nta, edda, dien). The former value is interpreted in terms of a mechanism in which ring closure is rate-determining and the latter by a mechanism in which the rate of solvent replacement is rate determining.