The synthesis and the molecular structure of hexakis (carbonyl)hexafluoroantimonato(V)tungsten(II) undecafluorodiantimonate (V), [W(CO)6(FSbF5)][Sb2F11]

The reaction of tungsten hexacarbonyl, W(CO)(6), with antimony(V) fluoride, SbF5, in the conjugate Bronsted-Lewis superacid HF-SbF5 at 40 degrees C produces quantitatively the salt [W(CO)(6)(FSbF5)][Sb2F11] as the main product. The observed 2e(-) oxidation without any loss of CO is unprecedented. The cation [W(CO)(6)(FSbF5)](+) is seven coordinated with a distorted C-2v capped trigonal prismatic structure. [W(CO)(6)(FSbF5)][Sb2F11] crystallizes in the monoclinic space group P-21 (No. 4). a 8.2051(12) Angstrom, b = 16.511(3) Angstrom, c = 8.1432(2) Angstrom, beta = 111.5967(6)degrees, V = 1025.8(2) Angstrom(3), Z = 2. Number of reflections measured = 9112, unique 4410. Residuals on F, I > 3 sigma(I): R (R-W) = 0.023 (0.23). In the [W(CO)(6)(FSbF5)](+) cation the FSbF5 group is very tightly coordinated to tungsten with the bridging fluorinenearly equidistant from W and Sb. The details of the molecular structure are compared to those of polymeric [{Mo(CO)(4)}(2)(cis-mu-F2SbF4)3](x)[Sb2F11](x) reported by us very recently.