INOR 345 |
| A systematic investigation of fluoride anion binding properties as a function of chelate backbone has been carried out for ferrocene functionalised boronic esters of the types FcB(OR)2 and fc[B(OR)2]2 (Fc = ferrocenyl; fc = ferrocendiyl). Cyclic boronic esters containing a saturated five- or six-membered chelate ring selectively bind fluoride in chloroform solution; the resulting complexes are characterized by weak binding (e.g. K = 35.8 ± 9.8 M-1 for FcBO2C2H2Ph2-S,S), and by cathodic shifts in the ferrocene oxidation potential that form the basis for electrochemical or colorimetric fluoride detection. By contrast, more elaborate Lewis acids based on calix[4]arene, such as (FcB)2calix, fcB2calix, or the previously reported (PhB)2calix, do not survive intact exposure to standard fluoride sources. Instead B-O bond cleavage occurs yielding the parent calixarene; the differences between alkoxo- and aryloxo-functionalised derivatives can be rationalised, at least in part, by consideration of the relative basicities of RO- (R = alkyl, aryl).
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Polyfunctional Organoboranes: From Molecules to Materials
7:00 PM-10:00 PM, Sunday, 10 September 2006 Moscone Center -- Hall D, Poster
Division of Inorganic Chemistry |
