STRUCTURE OF THE NEW FLUORO COMPLEX OF TUNGSTEN(VI) - [WF4(BIPY)2]2+.2[W2O2F9]-.0.25HF (BIPY=2,2'-BIPYRIDYL)

The complex [WF4(bipy)2]2+ . 2[W2O2F9]- . 0.25HF has been obtained by the controlled hydrolysis of a mixture of WF6 and 2,2'-bipyridyl (bipy) in CD2Cl2 solution. The crystal structure of this complex has been determined from X-ray diffraction data and refined to agreement factors of R = 0.061 and R(w) = 0.070 for 3484 unique reflections. The complex crystallizes in the triclinic system, space group P1BAR, with a = 10.995 (3) angstrom, b = 15.910 (3) angstrom, c = 21.478 (12) angstrom, alpha = 90.11 (3)-degrees, beta = 102.12 (3)-degrees, gamma = 100.58 (2)-degrees, Z = 4. Four [WF4(biPY)2]2+ cations, eight dimetallic anions [W202F9]-, formed by two WOF4 units bridged by a fluorine atom, and one HF molecule are found in the unit cell. The coordination polyhedron of the tungsten atom in the cation is a triangular dodecahedron, and in the anion it is a distorted octahedron around each metal centre. The ranges of the observed bond distances are (in angstrom): W-F, 1.79 (3)-1.87 (2); W-N, 2.21 (4)-2.30 (4) for the cation, and W-F terminal, 1.74 (4)-1.88 (4); W-F bridging, 2.05 (3)-2.16 (4); W-O, 1.58 (5)-1.72 (4) for the anion. The F-19 NMR spectra of the saturated solutions showed that the ion [W2O2F9]- is present and that the fluorine atoms of the cation are equivalent. The H-1 NMR spectra indicated that the protons of bipy in the cation are deshielded when compared with those of the free ligand in the same solvent.