Ligand exchange in the rhenium–quinone radical complexes: kinetics and mechanism

1983 ◽  
Vol 61 (5) ◽  
pp. 1017-1022 ◽  
Author(s):  
Katherine A. M. Creber ◽  
Jeffrey K. S. Wan
Keyword(s):  
Ligand Exchange ◽  
Esr Spectra ◽  
Donor Ligands ◽  
Carbonyl Groups ◽  
Exchange Reactions ◽  
Oxygen Donor ◽  
Competitive Ligand Exchange ◽  
Infrared Absorption Spectra ◽  
Relative Thermodynamic Stability ◽  
Nitrogen Phosphorus

The substitution of the labile carbonyl groups of the rhenium–quinone radical complexes by nitrogen, phosphorus, arsenic, antimony, and oxygen donor ligands was observed. The extent of substitution was evidenced from esr spectra, while the configuration of the ligands about the rhenium centre was deduced from infrared absorption spectra. Rate data was obtained for the mono-substitution reaction which can be best interpreted in terms of concurrent major dissociative (D) and minor dissociative interchange (Id) pathways. The relative thermodynamic stability of a number of substituted rhenium–quinone radical complexes was also investigated by competitive ligand exchange reactions.

scholarly journals Competitive ligand exchange reveals time dependant changes in the reactivity of Hg–dissolved organic matter complexes

2012 ◽  
Vol 9 (6) ◽  
pp. 495 ◽  
Author(s):  
Carrie L. Miller ◽  
Liyuan Liang ◽  
Baohua Gu
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Ligand Exchange ◽  
Aquatic Systems ◽  
Time Dependent ◽  
Exchange Reactions ◽  
Oak Ridge ◽  
Strength Of Interaction ◽  
Competitive Ligand Exchange ◽  
Over Time

Environmental contextMercury, a globally important pollutant, undergoes transformations in the environment to form methylmercury that is toxic to humans. Naturally occurring dissolved organic matter is a controller in these transformations, and we demonstrate that its strength of interaction with mercury is time dependent. These changes in complexation with dissolved organic matter are likely to affect mercury’s reactivity in aquatic systems, thereby influencing how mercury is methylated and bioaccumulated. AbstractMercury interactions with dissolved organic matter (DOM) are important in aquatic environments but the kinetics of Hg binding to and repartitioning within the DOM remain poorly understood. We examined changes in Hg–DOM complexes using glutathione (GSH) titrations, coupled with stannous-reducible Hg measurements during Hg equilibration with DOM. In laboratory prepared DOM solutions and in water from a Hg-contaminated creek, a fraction of the Hg present as Hg–DOM complexes did not react to GSH addition. This unreactive Hg fraction increased with time from 13 % at 1 h to 74 % after 48 h of equilibration with a Suwannee River DOM. In East Fork Poplar Creek water in Oak Ridge, Tennessee, ~58 % of the DOM-complexed Hg was unreactive with GSH 1 h after the sample was collected. This time-dependent increase in unreactive Hg suggests that Hg forms stronger complexes with DOM over time. Alternatively the DOM-complexed Hg may become more sterically protected from the ligand exchange reactions, as the binding environment changes within the DOM over time. These results have important implications to understanding Hg transformations in the natural environment, particularly in contaminated aquatic systems due to non-equilibrium interactions between Hg and DOM.

Voltammetric Studies of Some Novel Fe(III) Complexes with Quadridentate Ligands. The Axial Ligand-Exchange Reactions in DMF and DMSO

1995 ◽  
Vol 60 (7) ◽  
pp. 1140-1157 ◽  
Author(s):  
Ljiljana S. Jovanovic ◽  
Luka J. Bjelica
Keyword(s):  
Oxidation State ◽  
Chemical Reactions ◽  
Ligand Exchange ◽  
Kinetic Data ◽  
Central Atom ◽  
Axial Ligand ◽  
Exchange Reactions ◽  
Ligand Effect ◽  
Condensation Products ◽  
Voltammetric Studies

The electrochemistry of four novel Fe(III) complexes of the type [Fe(L)Cl], involving quadridentate ligands based on the condensation products of benzoylacetone-S-methylisothiosemicarbazone with salicylaldehyde, 5-chlorosalicylaldehyde, 3,5-dichlorosalicylaldehyde or 5-nitrosalicylaldehyde, was studied in DMF and DMSO at a GC electrode. All complexes undergo a two-step one-electron reductions, usually complicated by chemical reactions. In solutions containing Cl-, the ligand-exchange reactions Cl--DMF and Cl--DMSO take place. Stability of the chloride-containing complexes was discussed in terms of the coordinated ligand effect, oxidation state of the central atom and, in particular, of the donor effect of the solvent. Some relevant kinetic data were calculated.

A first-principles study of the atomic layer deposition of ZnO on carboxyl functionalized carbon nanotubes: the role of water molecules

2021 ◽  
Vol 23 (5) ◽  
pp. 3467-3478
Author(s):  
J. I. Paez-Ornelas ◽  
H. N. Fernández-Escamilla ◽  
H. A. Borbón-Nuñez ◽  
H. Tiznado ◽  
Noboru Takeuchi ◽  
...  
Keyword(s):  
First Principles ◽  
Ligand Exchange ◽  
Functional Group ◽  
Atomic Layer ◽  
High Reactivity ◽  
Water Molecules ◽  
Exchange Reactions ◽  
Layer Deposition ◽  
The Right

Atomic description of ALD in systems that combine large surface area and high reactivity is key for selecting the right functional group to enhance the ligand-exchange reactions.

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