The twinned crystal structure of tripotassium benzene-1,3,5-tris(trifluoroborate).
The title compound, 3K(+).C(6)H(3)B(3)F(9)(3-), crystallizes as discrete anions and cations which are connected by K...F and K...pi interactions. Two of the -BF(3) residues attached to the aromatic ring adopt a conformation with all F atoms out of the plane of the aromatic ring, whereas the third residue has an almost synperiplanar conformation for one of the F-B-C-C torsion angles. It is remarkable that only one of the K(+) cations interacts with the arene ring and that only one side of the aromatic ring coordinates to a K(+) cation. As a result, a sandwich structure does not occur. All K(+) ions show a coordination mode that cannot be conveniently described with a polyhedron. The anions are located in the (102) planes with the K(+) cations located between these planes. The investigated crystal was a nonmerohedral twin with the fractional contribution of the minor twin component being 0.405 (4). The title compound is the first example of a structure containing a benzene ring substituted with three -BF(3) groups. Only eight other structures have been reported in which a benzene ring carries at least one -BF(3) group. Just five of these contain a K(+) ion, but in none of these is the K(+) ion coordinated to the aromatic ring.
Franz
Daniel
D
Institut für Anorganische Chemie, J. W. Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main, Germany.
Wagner
Matthias
M
Lerner
Hans-Wolfram
HW
Bolte
Michael
M