Factors determining ion-pair formation. Studies of the radical anions of 2,5-bis(tricyanovinyl)furan and 2,5-bis(tricyanovinyl)thiophene
- 1 January 1995
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 2,p. 209-213
- https://doi.org/10.1039/p29950000209
Abstract
The specificity of ion-pair formation of the radical anions of 2,5-bis(tricyanovinyl)furan (1) and 2,5-bis(tricyanovinyl)thiophene (2) has been studied using solvents covering a broad range on the polarity scale and Li+, Na+, K+ and Cs+ as the counter-ions. The EPR/ENDOR spectra show that 1˙– and 2˙– can exist as the free radical anions in which the tricyanovinyl groups have a syn/anti conformation, but under appropriate conditions 2˙– can also exist in a syn/syn conformation in an ion-pair with the metal cation. This is rationalised in terms of a selectivity for the formation of ion pairs depending on the size of the alkali-metal cation and of the cavity presented by the proximate pair of cyano groups.Keywords
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