Synthesis and Structural Characterization of New Perfluoroacyl and Perfluoroalkyl Group 6 Transition Metal Compounds

A series of perfluoroacyl group 6 transition metal complexes Cp*M(CO)3[C(O)RF] and CpM(CO)3[C(O)RF] (M = Cr, Mo, W; RF = CF3, CF2CF3, CF2CF2CF3) have been synthesized by treatment of M(CO)6 with Cp*Li or CpNa in DME under reflux, followed by reaction with [RFC(O)]2O at −78 °C. The molecular structures of Cp*M(CO)3[C(O)CF3] (M = Cr, Mo, W) and Cp*Mo(CO)3[C(O)RF] (RF = CF2CF3, CF2CF2CF3) have been determined crystallographically. The chromium and molybdenum perfluoroacyl complexes were readily converted to the corresponding perfluoroalkyl complexes by heating under N2 in the solid state. The tungsten perfluoroacyl complexes were decarbonylated in refluxing toluene or xylene. The molecular structures of Cp*M(CO)3(CF3) (M = Cr and W) and Cp*Mo(CO)3(RF) (RF = CF2CF3, CF2CF2CF3) have been determined crystallographically. Structural comparisons within these compounds and with previously reported analogues are presented, allowing the first evaluations of the effect of the metal (M = Cr, Mo, W) on the M−CF3 parameters and the effect of fluoroalkyl chain length in Mo−RF (RF = CF3, CF2CF3, and CF2CF2CF3) to be made.