Preparation and spectroscopic characterization of the monofluorohydro-closo-borates [B6H5F](2-) and [B12H11F](2-)

By treatment of [B6H6](2-) with 1-(chloromethyl)-4-fluoro-1,4-diazabicyclo[2.2.2]octane-bis(tetrafluoroborate) in acetonitrile monofluorohydro-closo-hexaborate [B6H5F](2-) (1) is formed in good yields. [B12H12](2-) reacts with unhydrous HF yielding the monofluorododecaborate [B12H11F](2-) (2). These compounds are separated by ion exchange chromatography on diethylaminoethyl(DEAE) cellulose from by-products. The B-11 nmr spectra exhibit the characteristic patterns (1:4:1) of a monosubstituted Bg octahedron and (1:5:5:1) of a monosubstituted B-12 icosahedron with strong downfield shifts of the ipso-B nuclei at +9.3 ppm (1) and at +9.0 ppm (2). The F-19 nmr spectra reveal quartets at -212 ppm (1) and -209 ppm (2) proving a B-F bonding. In the i.r. spectra, for (1) in the Raman spectrum too, cage vibrations depending on the F substituent at 1195 (1) and at 1182/1154 cm(-1) (2) are observed. The Raman spectra show the B6F stretching mode at 535 cm(-1) and the B12F stretching vibration at 445 cm(-1).