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Redox and Acid - Base Chemistry of TCNQ, TCNQ•-, TCNQ2- and H2TCNQ (TCNQ = 7,7,8,8-tetracyanoquinodimethane) in Acetonitrile.
MedLine Citation:
PMID:  22229829     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The chemistry and electrochemistry of TCNQ (7,7,8,8-tetracyanoquinodimethane), TCNQ•-, TCNQ2- and H2TCNQ in acetonitrile (0.1 M Bu4NPF6) solution containing trifluoroacetic acid (TFA) has been studied by transient, and steady-state voltammetric methods with the interrelationship between the redox and the acid-base chemistry being supported by simulations of the cyclic voltammograms. In the absence of acid, TCNQ and its anions undergo two electrochemically and chemically reversible one-electron processes. However, in the presence of TFA, the voltammetry is considerably more complex. The TCNQ2- dianion is protonated to form HTCNQ-, which is oxidized to HTCNQ•, and H2TCNQ, which is electroinactive over the potential range of -1.0 to +1.0 V vs. Ag/Ag+. The monoreduced TCNQ•- radical anion is weakly protonated to give HTCNQ•, which disproportionates to TCNQ and H2TCNQ. In acetonitrile, H2TCNQ deprotonates slowly, whereas in N,N-dimethylformamide or tetrahydrofuran, rapid deprotonation occurs to yield HTCNQ- as the major species. H2TCNQ is fully deprotonated to the TCNQ2- dianion in the presence of an excess concentration of the weak base, CH3COOLi. Differences in the redox and acid-base chemistry relative to the fluorinated derivative TCNQF4 are discussed in term of structural and electronic factors.
Authors:
Thanh Hai LE; Ayman Nafady; Xiaohu Qu; Alan M Bond; Lisandra L Martin
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-9
Journal Detail:
Title:  Analytical chemistry     Volume:  -     ISSN:  1520-6882     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370536     Medline TA:  Anal Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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