BF4− as a probe for ion pair solution structure using interionic one- and two-dimensional 19F{1H} NOEs
✍ Scribed by Christine Hofstetter; Thomas C. Pochapsky
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 98 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Interionic 19 Ff 1 Hg NOEs were observed in tetrabutylammonium tetrafluoroborate (1) in CDCl 3 solution using both one-dimensional steady-state NOE difference experiments and a two-dimensional 19 Ff 1 Hg HOESY technique. The two-dimensional 19 Ff 1 Hg HOESY experiment was also used to identify BF 4 binding sites on a more complex cation, 8˛-9(R)-hydroxy-1-(anthrylmethyl)cinchonanium (2), in CDCl 3 . The time-average structures of the respective ion pairs are discussed. For the smaller ion pair formed by 1, the observed 19 Ff 1 Hg NOEs are positive in sign, indicating that the extreme narrowing limit is approached. For the larger ion pair 2, 19 Ff 1 Hg NOEs are negative in sign, with evidence for extensive spin diffusion within the ion pair, indicating a significant increase in correlation time relative to ion pair 1.