Premium
BF 4 − as a probe for ion pair solution structure using interionic one‐ and two‐dimensional 19 F{ 1 H} NOEs
Author(s) -
Hofstetter Christine,
Pochapsky Thomas C.
Publication year - 2000
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(200002)38:2<90::aid-mrc608>3.0.co;2-p
Subject(s) - chemistry , ion , sign (mathematics) , tetrafluoroborate , diffusion , crystallography , nuclear magnetic resonance , thermodynamics , organic chemistry , mathematical analysis , ionic liquid , physics , mathematics , catalysis
Interionic 19 F{ 1 H} 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 F{ 1 H} HOESY technique. The two‐dimensional 19 F{ 1 H} HOESY experiment was also used to identify BF 4 − binding sites on a more complex cation, 8 α ‐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 F{ 1 H} NOEs are positive in sign, indicating that the extreme narrowing limit is approached. For the larger ion pair 2 , 19 F{ 1 H} 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 . Copyright © 2000 John Wiley & Sons, Ltd.