Investigation of the kinetics of aquation of the 1:2 complex between CrIII and nitrilotriacetic acid

Kinetics of aquation of the 1:2 complex between CrIII and nitrilotriacetic acid (NTA) was measured using a combination of capillary electrophoresis (CE), UV-Vis spectrophotometry, and ATR-FTIR spectroscopy. The aquation products were identified as the 1:1 CrIII complex with NTA and “free” NTA. Observed first-order rate constants, kobs, exhibited a complicated pH dependence which was successfully modeled by considering five distinct reaction pathways. The 1:1 complex dimerized to form a 2:2 complex in a slower subsequent reaction step.