POTASSIUM TRIFLUOROPHENYLBORATE

X-ray structural analysis confirms that the title compound, potassium trifluorophenylborate, K+.C6H5BF3- contains the first structurally characterized example of a trifluorophenylborate anion. The C-C bond lengths of the phenyl ring lie within the range 1.38 (2)-1.41 (2) Angstrom, consistent with pi-electron delocalization; the three B-F bond lengths are 1.41(1), 1.41(1) and 1.43 (1) Angstrom. The anion can be considered as a Lewis acid complex of BF3 and Ph(-), and as expected from a simple VSEPR model, the geometry around the B atom is tetrahedral, although the presence of two different substituents around the B atom results in two distinct sets of bond angles, with significantly smaller values for the three F-B-F angles [104.4(7), 106.0(7) and 106.7(9)degrees] compared with the remaining three C(phenyl)-B-F angles [112.1(7), 112.9 and 114.1(7)degrees].