A General Route to Perfluoroalkyl‐ and Trifluorovinyl‐Substituted Fischer Carbene Complexes of Tungsten and Chromium – Syntheses, Characterisation and Structures

Hexacarbonyltungsten and -chromium [M(CO)6; M = W, Cr] react smoothly with perfluoroalkyl (Rf = CF3, C2F5) and trifluorovinyl (Rf = CF=CF2) silanes in the presence of equimolar amounts of fluoride ions with exclusive attack of one of the CO ligands to form the corresponding salts, Cat[(CO)5MC(Rf)O] (Cat = [Me4N]+, [Cs(15-crown-5)2]+) which after methylation represent the first hitherto unknown perfluoroorgano-substituted Fischer carbene complexes, (CO)5MC(Rf)(OCH3), of those metals. The methoxy group can be easily replaced by amino functional groups as shown for the corresponding carbonyltungsten compound. The molecular structures of (CO)5WC(CF3)(OCH3) and (CO)5WC(CF3)[N(C2H5)2] have been elucidated by XRD measurements.