Solution studies of vanadium(IV), vanadium(V), and vanadium(IV,V) complexes with methionine in 3.0 mol LZ1 KCl ionic medium at 25 C

Abstract

A study of the Hþ–VO2þ-methionine, Hþ–VOþ 2 –methionine, and Hþ–V2O3þ 3 –methionine (ligand, HL) systems by emf(H) measurements in 3.0 mol L 1 KCl ionic medium at 25 C is presented here. Data analysis using the LETAGROP program indicate formation of vanadium(IV) species [HVOL]2þ, [VOL]þ, and [H2VOL2]2þ; vanadium(V) species [HVO2L]þ and VO2L; and the mix-valence vanadium(IV,V) species [H2V2O3L]4þ, [V2 O3L]2þ, [OHV2O3L]þ, (OH)2V2O3L, (OH)3V2O3L, [HV2O3L2]2þ, [V2O3L2]þ, and OHV2O3L2, whose stability constants pqrs were determined according to the general reaction p Hþþq VO2þþr VOþ 2 þs L ! HpðVOÞqðVO2ÞqLð pþ2qþr sÞ r . Selected structural parameters of some complexes formed in solution were determined using ab initio methods.