The hydrolysis of VO2+ and the complex with sulfate were studied potentiometrically, spectrophotometrically and calorimetrically, in NaCl aqueous solution (0 < I ≤ 1 mol L− 1) and at t = 25 °C. The formation of two hydrolytic species VO(OH)+ and VO2 (OH)22+ and one complex with sulfate was found, with log β = − 5.65 for the reaction VO2+ + H2 O = VO(OH)+ + H+, log β = − 7.02 for the reaction 2VO2+ + 2H2 O = (VO)2 (OH)22+ + 2H+ and log K = 1.73 for VOSO40 species (at I = 0.1 mol L− 1 and t = 25 °C). For these species, using calorimetric data, ΔH and T ΔS values were also obtained. By using the above values, interactions of VO2+ with acetate (ac), malonate (mal), succinate (suc), 1,2,3-propanetricarboxylate (tca) and 1,2,3,4-butanetetracarboxylate (btc) ligands were studied potentiometrically and spectrophotometrically. The formation of ML+, ML20 and MLOH0 for ac; ML0, MLH+, ML22− and ML2 H− for mal; ML0, MLH+ and MLOH− for suc; ML− and MLH0 for tca and ML2−, MLH− and MLH20 for btc were found. Formation constants are reported at I = 0.1 mol L− 1, together with SIT parameters for the dependence on ionic strength. By visible spectrophotometric measurements, λmax and εmax values for the relevant species in solution were determined.
Interaction of oxovanadium(IV) with carboxylic ligands in aqueous solution: A thermodynamic and visible spectrophotometric study
BERTO, Silvia;DANIELE, Pier Giuseppe;PRENESTI, Enrico;
2008-01-01
Abstract
The hydrolysis of VO2+ and the complex with sulfate were studied potentiometrically, spectrophotometrically and calorimetrically, in NaCl aqueous solution (0 < I ≤ 1 mol L− 1) and at t = 25 °C. The formation of two hydrolytic species VO(OH)+ and VO2 (OH)22+ and one complex with sulfate was found, with log β = − 5.65 for the reaction VO2+ + H2 O = VO(OH)+ + H+, log β = − 7.02 for the reaction 2VO2+ + 2H2 O = (VO)2 (OH)22+ + 2H+ and log K = 1.73 for VOSO40 species (at I = 0.1 mol L− 1 and t = 25 °C). For these species, using calorimetric data, ΔH and T ΔS values were also obtained. By using the above values, interactions of VO2+ with acetate (ac), malonate (mal), succinate (suc), 1,2,3-propanetricarboxylate (tca) and 1,2,3,4-butanetetracarboxylate (btc) ligands were studied potentiometrically and spectrophotometrically. The formation of ML+, ML20 and MLOH0 for ac; ML0, MLH+, ML22− and ML2 H− for mal; ML0, MLH+ and MLOH− for suc; ML− and MLH0 for tca and ML2−, MLH− and MLH20 for btc were found. Formation constants are reported at I = 0.1 mol L− 1, together with SIT parameters for the dependence on ionic strength. By visible spectrophotometric measurements, λmax and εmax values for the relevant species in solution were determined.File | Dimensione | Formato | |
---|---|---|---|
oxovanadium(IV) carboxylic ligands.pdf
Accesso riservato
Tipo di file:
POSTPRINT (VERSIONE FINALE DELL’AUTORE)
Dimensione
490.9 kB
Formato
Adobe PDF
|
490.9 kB | Adobe PDF | Visualizza/Apri Richiedi una copia |
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.