FLUORIDE-ION DEBORONATION OF P-FLUOROPHENYL-ORTHO-CARBORANES AND P-FLUOROPHENYL-META-CARBORANES - NMR EVIDENCE FOR THE NEW FLUOROBORATE, HOBHF2-

The reactions of 1-(4-fluorophenyl)-1,2-dicarbadodecaborane(12) 1 and 1-(4-fluorophenyl)-1,7-dicarbadodecaborane(12) 2 with tetrabutylammoni um fluoride hydrate in tetrahydrofuran or acetonitrile have been monit ored by F-19 and B-11 NMR. No carborane intermediates were observed pr ior to formation of the nido-anions 7-(4-FC6H4)-7,8-C2B9H11- 3 and 7-( 4-FC6H4)-7,9-C2B9H11- 4 which each required two molecular proportions of fluoride and, by inference, one of water for complete reaction. The spectra of the initial anionic monoboron product of both reactions sh owed it to be the new fluoroborate HOBHF2- 5. The B-attached hydrogen atom of the fluoroborate 5 is derived from the starting carborane, sin ce it was retained when Bu4NF.(D2O)(n) was used, but the nido-anions 3 and 4 bonded deuterium at the open face in this experiment. The H-1, B-11, F-19 and C-13 NMR spectra of carboranes 1-4 have been recorded a nd assigned. (C) 1997 Elsevier Science Ltd.