Kinetics of cerium(IV) oxidation of macrocyclic complexes of chromium(III) and fate of chromium(IV) intermediates

✍ Scribed by Balachandran Unni Nair; T. Ramasami; D. Ramaswamy

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 777 KB
• Volume: 19
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550190403

✦ Synopsis

Kinetics and mechanism of the cerium(1V) oxidation of Cr(II1) complexes of a series of macrocyclic (or pseudomacrocyclic) ligands with L14l-membered intraligand rinqsizes have now been investigated at I = 1.0 Tvf !LiClO.d Temp. 30°C. The complexes of' the formulation Cr(macrocycle)(X)(H20)'3 ''I-where X = CHCl, and H,O, n = 0 n r 1 undergo oxidation to Cr(V1) with the formation of chromium(1V) intermediates. The observed kinetic parameters for the Ce(1V) oxidation of Cr(II1) macrocyclic complexes have been discussed in terms of changes brought about by the macrocyclic ligands on the Cr(I1I)-Cr(IV) redox potentials and in specific rates for Cr(1V) -Cr(V) conversion. On the basis of this study, it has been suggested that the trapping of Cr(1Vi is easier when a macrocyclic ligand having a symmetrical intra-ligand ring size an.d unsatiiration in f he cyclic structure is coordinated equatorially. Cyclic voltammetric studies indicate the formation of Cr(1V) transient in the case of electrochemical oxidation of trans-Cr(Mel[ 14]tetraenej(H20)~+.