Kinetic studies of ligand substitution rates for the Ru(NH/sub 3/)/sub 5/(H/sub 2/O)/sup 2 +/ ion in Nafion films

Journal Article · Wed Oct 01 00:00:00 EDT 1986 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00280a001· OSTI ID:5058431

Lieber, C M; Schmidt, M H; Lewis, N S

Substitution rates have been measured for reaction of a number of pyridines with the Nafion-bound Ru(NH/sub 3/)/sub 5/(H/sub 2/O)/sup 2 +/ complex. Reaction activities have been determined by electrochemical techniques, which also allow for determination of site thermodynamics and heterogeneity during the course of the reaction. Diffusion-coefficient effects are investigated by variation in polymer film thickness, and partition coefficients have been determined under equilibrium conditions by optical absorbance techniques. The partition-coefficient corrected rate law is found to be first order in Nafion-bound (Ru/sup II/) and first order in ligand concentration in the polymer phase. The partition-coefficient corrected bimolecular rate constants for a variety of pyridine ligands are found to vary by a factor of 5, which contrasts with the relatively constant substitution rates observed in aqueous solution. Also, sterically hindered ligands, such as 2-propylpyridine, exhibit surprisingly high substitution rate constants on the Nafion-bound Ru/sup II/ ion. These rate data indicate that pronounced molecular reactivity changes can occur upon electrode modification and have implications with respect to the design of chemically modified electrodes for use in electrocatalysis.

• Research Organization: Stanford Univ., CA
• OSTI ID: 5058431
• Journal Information: J. Am. Chem. Soc.; (United States), Vol. 108:20
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AMMONIA
CHEMICAL REACTIONS
COATINGS
PERFORMANCE
ELECTRODES
DESIGN
HYDRATES
PYRIDINES
RUTHENIUM COMPLEXES
THIN FILMS
AQUEOUS SOLUTIONS
CATALYSIS
CHEMICAL REACTION KINETICS
DIFFUSION
EQUILIBRIUM
EXPERIMENTAL DATA
LIGANDS
POLYMERS
STEREOCHEMISTRY
THERMODYNAMICS
AZINES
COMPLEXES
DATA
DISPERSIONS
FILMS
HETEROCYCLIC COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
KINETICS
MIXTURES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
REACTION KINETICS
SOLUTIONS
TRANSITION ELEMENT COMPLEXES
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)
400400 - Electrochemistry