Studies on the equilibria in Ag(I) - 1,4,8,11-tetraazacyclotetradecane and Ag(I) - 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane systems in water |
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Authors: | A. Grzejdziak |
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Affiliation: | (1) Department of General and Inorganic Chemistry, University of Lód, PL-90-136 Lód, Poland |
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Abstract: | Summary Protonation constants of 1,4,8,11-tetraazacyclotetradecane (T ACT) and 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (TMT ACT) (=0.1) were determined bypH-metry. The values are logK1=10.922, logK2=10.511, logK3=2.646, logK4=1.620 forT ACT, and logK1=9.387, logK2=9.050, logK3=2.491, logK4=1.380 forTMTACT. Absorption maxima of the complexes AgTA CT(NO3)2 and AgTMTACT(NO3)2 were found to be 1=280 nm, 2=350 nm, and 1=290 nm, 2=400 nm, respectively. The disproportionation constants of Ag(I) ions in the presence of the amines were determined by potentiometry: forTA CT logKd=12.778, and forTMT ACT logKd=11.778. The mechanisms of the electrode processes taking place in solutions of the complexes under investigation were examined by means of chronovoltamperometric and coulometric measurements. The formal potential,Ef0, of the system: AgTMT ACT2++e AgTMT ACT+ is +0.450 V vs. NHE.
Untersuchungen zu den Gleichgewichten Ag(I) -1,4,8,11-Tetraazacyclotetradekan und Ag(I) -1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradekan in Wasser Zusammenfassung Die Protonierungskonstanten von 1,4,8,11-Tetraazacyclotetradekan (TACT) und 1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradekan (TMT ACT) wurdenpH-metrisch bei =0.1 bestimmt. Folgende Werte wurden ermittelt: logK1=10.922, logK2=10.511, logK3=2.646, logK4=1.620 fürTACT und logK1=9.387, logK2=9.050, logK3=2.491, logK4=1.380 fürTMT ACT. Die Absorptionsmaxima der Komplexe AgTACT(NO3)2 und AgTMTACT(NO3)2 waren 1=280 nm, 2=350 nm, bzw. 1=290 nm, 2=400 nm. Die Disproportionierungskonstanten der Ag(I)-Ionen in Gegenwart der Amine wurden potentiometrisch bestimmt: logKd=12.778 fürTACT und logKd=11.778 fürTMTACT. Der Mechanismus des Elektrodenprozesses in den Komplexlösungen wurde mittels Chronovoltamperometrie und Coulometrie überprüft. Das formale PotentialEf0 des Systems AgTMT ACT2++eAgTMT ACT+ ist +0.450 V gegenüber NHE. |
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Keywords: | Chronovoltammetry Coulometry Formal potential Redox systems Silver complexes Tetraazamacrocyclic amines Water |
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