TRIFERROCENYL-COMPLEXE VON WOLFRAM(VI): MOLEKUELSTRUKTUR IM FESTKOERPER UND DYNAMISCHES VERHALTEN IN LOESUNG VON TRIFERROCENYL-FERROCENOXY-OXO-WOLFRAM, WO(OFc)Fc3

Article abstract of DOI:10.1016/0022-328X(86)80040-7

Triferrocenyltungsten complexes of the type WO(X)Fc3 (X=Cl, (1), OMe (2), OFc (3) and OnBu (4)) were obtained by treating WOCl4 with ferrocenyllithium, FcLi, in tetrahydrofuran solution.Reaction of WOCl4 with a threefold excess of FcLi gives 1, which may be converted into 2 using KOCH3.Reaction of WOCl4 with a sixfold excess of FcLi gives a mixture containing 3 und 4 in addition to ferrocene and biferrocene.According to the X-ray crystallographic analysis, WO(OFc)Fc3 (3) has a trigonal-bipyramidal structure with three ferrocenyl ligands occupying the equatorial positions and an axial ferrocenoxy group coordinated trans to the oxo ligand The three W-C(ferrocenyl) (average 2.092 angstroem) and the O-C(ferrocenyl) (1.33(1) angstroem) bond distances are remarkably short.The axial tungsten-oxygen distances correspond to a W=O double and a W-O single bond (1.705(5) and 1.945(5) angstroem), respectively.The 1H and 13C NMR spectra of WO(OFc)Fc3 (3) are temperature-dependent.This is ascribed to a hindered rotation of the ferrocenyl ligands around the W-C(ferrocenyl) bonds; the free activation enthalpy ΔG(excit.)(Tc) of this intramolecular dynamic process is 62.5 +/- 0.5 kJ mol^-1.