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NMR studies of strong hydrogen bond to fluoride ion

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Show simple item record Kanippayoor, Raveendran K. en_US 2009-07-09T18:39:14Z 2009-07-09T18:39:14Z 1979-07-09T18:39:14Z
dc.description.abstract Systems such as MF/diol (M = alkali metal) and }1F/carboxylic acid were subjected to IH, I9F and 13C nmr study to investigate the nature of the very strong H-bonding of fluoride ions with these systems. Evidence indicates a strong H-bond in diol-fluoride systems (~H ~ -(56) kJ mol-I) which is stronger than most 'typical' H-bonds (~H = -(12-40) kJ mol-I), but weaker than that reported for carboxylic acid-fluoride systems (~H ~ -(120) kJ mol-I). Approximate fluoride H-bonded shifts (o(OH)OHF) were evaluated for MF/diol systems from IH chemical shift measurements. No direct correlation was observed between I9F chemical shift and H-bond strength. Thermodynamic parameters were calculated from temperature dependent IH and 19F shifts. Preliminary studies of BUn 4NF-acetylacetone by I9F nmr were conducted at low temperatures and a possible Jmax (ca. 400 Hz) is reported for the fluoride ion H-bonded to acetylacetone. Highfield shift for non-protonated carbons and downfield shift for protonated carbons were observed in carboxylic acid/KF systems. Significant decreas$in I3C TI due to strong H-bonding to fluoride ions were also detected in both diol and carboxylic acid systems. Anomalous results were obtained, such as increasing NOE with increasing temperature in neat 1,2-ethanediol (values above the theoretical maximum of 1.988) and in 1,2-ethanediol/KF. The large 13C NOE's for carboxy carbons in neat carboxylic acids which are. further enhanced by the addition of KF are also unusual. en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Hydrogen bonding. en_US
dc.subject Fluorides. en_US
dc.subject Ions. en_US
dc.subject Nuclear magnetic resonance spectroscopy. en_US
dc.title NMR studies of strong hydrogen bond to fluoride ion en_US
dc.type Electronic Thesis or Dissertation en_US M.Sc. Chemistry en_US Masters en_US
dc.contributor.department Department of Chemistry en_US Faculty of Mathematics and Science en_US

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