Abstract:FRANCISCO ORTEGA and ELVIRA RODENAS. Can. J. Chem. 67,305 (1989).The rate of reaction of tris(1 , 10-phenanthroline)iron(II) ion (la), tris(3,4,7,8-tetramethyl-1 , 10-phenanthroline)iron(II) ion (lb), and tris(4,7-diphenyl-I, 10-phenanthroline)iron(II) ion (lc) with hydroxideion, in cationic micelles, is strongly affected by the concentration of micellar counterion in solution. The reaction of l a in CTACl is modestly speeded up by the addition of added KCI, while the reactions of 1 band l c are strongly inhib… Show more
“…5). The observed kinetic results corroborate the same of Ortega and Rodenas [8]. The results represent a typical effect of the surfactant's counterion Br − .…”
Section: Effect Of the Sodium Hydroxide Concentration On The Ratesupporting
confidence: 88%
“…All three interactions can play a crucial role in altering the rate of the reaction 4,5 and the reaction pathway by changing its microenvironment in the surrounding area of reacting species. Many researchers studied the kinetics and mechanism of the basic hydrolysis of tris(1,10‐phenanthroline)iron(II) in aqueous and micellar medium 6–8. The Fe(II) complex is brightly colored and stable in wide pH range of 2–9 6.…”
The kinetics of basic hydrolysis of tris(1,10-phenanthroline)iron(II)has been carried out in aqueous, N-cetyl-N,N,N-trimethyl ammonium bromide (CTAB) micellar, and CTAB reverse micellar media by UV-visible spectroscopy system. The reaction follows the overall second-order kinetics; first order in each Fe(II) complex and the base ( − OH). CTAB micelles catalyze the reaction rate through the adsorption of the Fe(II) complex and the hydroxyl ions on the micellar surface. In the reverse micellar medium, interesting physicochemical features are observed. Being ionic nature of reactants, both the reactants prefer to stay and react inside the water pool in place of the hydrophobic environment. The rate increases with w, that is, the size of the water pool, attains a maximum value at w = 8.33, and then decreases. But the rate increases as the concentration of surfactant increases at fixed w values. For a better explanation of the kinetic data, the activation parameters, standard enthalpy of activation ( ‡ H • ), standard entropy of activation ( ‡ S • ), and energy of activation (E a ) were determined.in surfactant-based organized assemblies, such as micelles, microemulsions, and vesicles, often achieve a greater degree of organization compared to their geometries in homogeneous continuous solution, can mimic reactions in biosystems, and also have potential for energy storage [1]. Micellar medium is a heterogeneous system where a given solvent is isolated from a continuous phase solvent by a surfactant or a pair of surfactants and a cosurfactant. It can catalyze many reactions due to the concentration effect in the micellar pseudophase [2] and can also change the reaction pathway [3]. Such organized media
“…5). The observed kinetic results corroborate the same of Ortega and Rodenas [8]. The results represent a typical effect of the surfactant's counterion Br − .…”
Section: Effect Of the Sodium Hydroxide Concentration On The Ratesupporting
confidence: 88%
“…All three interactions can play a crucial role in altering the rate of the reaction 4,5 and the reaction pathway by changing its microenvironment in the surrounding area of reacting species. Many researchers studied the kinetics and mechanism of the basic hydrolysis of tris(1,10‐phenanthroline)iron(II) in aqueous and micellar medium 6–8. The Fe(II) complex is brightly colored and stable in wide pH range of 2–9 6.…”
The kinetics of basic hydrolysis of tris(1,10-phenanthroline)iron(II)has been carried out in aqueous, N-cetyl-N,N,N-trimethyl ammonium bromide (CTAB) micellar, and CTAB reverse micellar media by UV-visible spectroscopy system. The reaction follows the overall second-order kinetics; first order in each Fe(II) complex and the base ( − OH). CTAB micelles catalyze the reaction rate through the adsorption of the Fe(II) complex and the hydroxyl ions on the micellar surface. In the reverse micellar medium, interesting physicochemical features are observed. Being ionic nature of reactants, both the reactants prefer to stay and react inside the water pool in place of the hydrophobic environment. The rate increases with w, that is, the size of the water pool, attains a maximum value at w = 8.33, and then decreases. But the rate increases as the concentration of surfactant increases at fixed w values. For a better explanation of the kinetic data, the activation parameters, standard enthalpy of activation ( ‡ H • ), standard entropy of activation ( ‡ S • ), and energy of activation (E a ) were determined.in surfactant-based organized assemblies, such as micelles, microemulsions, and vesicles, often achieve a greater degree of organization compared to their geometries in homogeneous continuous solution, can mimic reactions in biosystems, and also have potential for energy storage [1]. Micellar medium is a heterogeneous system where a given solvent is isolated from a continuous phase solvent by a surfactant or a pair of surfactants and a cosurfactant. It can catalyze many reactions due to the concentration effect in the micellar pseudophase [2] and can also change the reaction pathway [3]. Such organized media
“…Chemical Behavior. Iron complexes have been known for many years to undergo rather rapid ligand substitution reactions and to have a very strong attraction to certain anions such as chloride, bromide, and thiocyanate, which have all been shown to cause thermal dissociation reactions. − Such reactions are accelerated in the presence of light. Ruthenium complexes, on the other hand, are stable under most conditions but do undergo slow photosubstitution in the presence of excess halide …”
Section: Discussionmentioning
confidence: 99%
“…In an attempt to understand the variation in the properties between iron(II) and ruthenium(II) and the differences in stability between iron(II) diimine complexes, we report a general computational study on four iron(II) complexes used to ascertain these differences. We , and others , have examined ruthenium(II) complexes in the past; here we focus on three iron(II) diimine systems, 2,2‘-bipyridine, 2,2‘-bipyrazine, and 1,10-phenanthroline, − and one iron (II) triimine, Fe(terpy) 2 2+ , where terpy is 2,2‘:6‘,2‘ ‘-terpyridine, shown in Figure . 1 Schematic drawing of complexes 1 − 4 .…”
Density functional theory (DFT) calculations show the higher energy HOMO (highest occupied molecular orbital) orbitals of four iron(II) diimine complexes are metal centered and the lower energy LUMO (lowest unoccupied molecular orbitals) are ligand centered. The energy of the orbitals correlates with electrochemical redox potentials of the complexes. Time-dependent density functional theory (TDDFT) calculations reveal ligand centered (LC) and metal-to-ligand charge transfer (MLCT) at higher energy than experimentally observed. TDDFT calculations also reveal the presence of d-d transitions which are buried under the MLCT and LC transitions. The difference in chemical and photophysical behavior of the iron complexes compared to that of their ruthenium analogues is also addressed.
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