Electron-self-exchange reactions in solid-state voltammetry. The radical anion of 7,7,8,8-tetracyanoquinodimethane in polymer electrolytes. 1

Journal Article · Thu May 30 00:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100164a071· OSTI ID:5890150

Watanabe, M; Wooster, T T; Murray, R W ^[1]

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1. Univ. of North Carolina, Chapel Hill (United States)

Voltammetric currents for the oxidation of the lithium salt of the 7,7,8,8-tetracyanoquinodimethane anion radical (LiTCNQ) at Pt microdisk electrodes in network poly(ethylene oxide) (PEO) polymer solvent are substantially larger than currents for its reduction. The difference in currents is interpreted as a combination of electron self-exchange (between TCNQ{sup {sm bullet}{minus}} and TCNQ{sup 0}) and electrostatic migration. The latter is a minor effect in the presence of LiClO{sub 4} electrolyte as shown by a transference number (t{sub TCNQ}) analysis. At (LiClO{sub 4}) {le} 0.4 M, the product k{sub ex,1/0}{delta}{sub 1/0}{sup 2} of electron-self-exchange rate constant and hopping distance (squared) for the TCNQ{sup {minus}/0} couple is 1.0 ({plus minus}0.3) {times} 10{sup {minus}6} cm{sup 2} M{sup {minus}1} s{sup {minus}1}. Assuming {delta}{sub 1/0} = 9.5 {angstrom} gives k{sub ex,1/0} = 1 {times} 10{sup 8} M{sup {minus}1} s{sup {minus}1} in the polymer solvent, which is 47-fold smaller than k{sub ex,1/0} in acetonitrile solvent and 7-fold larger than measurable by methods subject to diffusion-controlled collision rate considerations. Physical diffusion is also slow in the polymer solvent and connections of this to k{sub ex,1/0} are discussed, including encounter rate limitations, longer polymer solvent dipole relaxation times, and longer distance electron transfers.

• DOE Contract Number: FG05-87ER13675
• OSTI ID: 5890150
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:11; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400* -- Electrochemistry
ALCOHOLS
ALKALI METAL COMPOUNDS
ANIONS
AROMATICS
AZAARENES
AZINES
CHARGED PARTICLES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CURRENTS
DATA
DIFFUSION
ELECTRIC CURRENTS
ELECTRON EXCHANGE
ELECTRON TRANSFER
EXPERIMENTAL DATA
GLYCOLS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
IONS
KINETICS
LITHIUM COMPOUNDS
MATHEMATICAL MODELS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC POLYMERS
POLYETHYLENE GLYCOLS
POLYMERS
PYRIDINES
QUINOLINES
RADICALS
REACTION KINETICS
REDUCTION
SOLIDS
VOLTAMETRY