title: Simultaneous fluoride binding to ferrocene-based heteronuclear bidentate Lewis acids.
abstract: A series of micro2-fluoro-bridged heteronuclear bidentate Lewis acid complexes [K(18-crown-6)THF]+ [Fc(BMeF)(SnMe2Cl)F]- (1-2F), [K(18-crown-6)THF]+ [Fc(BMeF)(SnMe2F)F]- (1-3F), [K(18-crown-6)THF]+ [Fc(BMePh)(SnMe2Cl)F]- (2-F), and [K(18-crown-6)THF]+ [Fc(BMePh)(SnMe2F)F]- (2-2F) (Fc=1,2-ferrocenediyl) was prepared. Compounds 2-F and 2-2F were obtained as a mixture of diastereomers, which arise due to the generation of a stereocenter at boron in addition to their inherent planar chirality. All compounds have been studied in the solid state by single-crystal X-ray diffraction analysis and by multinuclear NMR spectroscopy in solution. As a result of bridging-fluoride interactions, tetrahedral boron and distorted trigonal-bipyramidal tin centers are observed. Comparison with the corresponding monofunctional ferrocenylborates further supports the bridging nature of the fluoride anion. Two-dimensional exchange spectroscopy 19F NMR studies provide evidence for facile intermolecular and intramolecular fluorine exchange processes. All complexes display reversible one-electron oxidation events at lower potentials than those of the tricoordinate ferrocenylborane precursors, which is typical of ferrocenylborate complexes.
authors.affiliation: Department of Chemistry, Rutgers University, Newark, 73 Warren Street, Newark, New Jersey 07102, USA.
authors.forename: Ramez
authors.initials: R
authors.lastname: Boshra
authors.forename: Krishnan
authors.initials: K
authors.lastname: Venkatasubbaiah
authors.forename: Ami
authors.initials: A
authors.lastname: Doshi
authors.forename: Roger A
authors.initials: RA
authors.lastname: Lalancette
authors.forename: Lazaros
authors.initials: L
authors.lastname: Kakalis
authors.forename: Frieder
authors.initials: F
authors.lastname: Jäkle