Study of the ligand substitution reaction Fe (CN)5H2O3− + pyrazine in micellar solutions

✍ Scribed by María del Mar Graciani; María Amalia Rodríguez; María Luisa Moyá

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 131 KB
• Volume: 29
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/(sici)1097-4601(1997)29:5<377::aid-kin8>3.0.co;2-r

✦ Synopsis

The ligand substitution reaction Fe(CN) 5 H 2 O 3Ϫ ϩ pyrazine : Fe(CN) 5 pyrazine 3Ϫ ϩ H 2 O has been studied in sodium dodecyl sulfate, SDS, hexadecyltrimethylammonium bromide, CTAB, and salt aqueous solutions at 298.2 K. Kinetics were studied in dilute and concentrated salt solutions and in SDS and CTAB solutions at surfactant concentrations below and above the critical micelle concentration. Experimental results show that salt effects can be explained by considering the interaction between the cations present in the working media, which come from the background electrolyte, and the Fe(CN) 5 H 2 O 3Ϫ species in the vicinity of the cyanide ligands. This interaction makes the release of the aqua ligand from the inner-coordination shell of the iron(II) complex to the bulk more difficult, resulting in a decrease of the reaction rate when the electrolyte concentration increases. Kinetic data in surfactant solutions show that not only micellized surfactants are operative kinetically, but also nonmicellized surfactants are influencing the reactivity.