An Ylidic Cp and its Scandium Complexes in Equilibrium

Scandium complexes
bearing a C-ylidic, electron-deficient
Cp ligand are presented by starting from [ScCl3(thf)3]. As ylidic ligands do not require salt metathesis, the coordination
of the Cp ligand is realized by mere substitution of the tetrahydrofuran
ligands. In acetonitrile an equilibrium among the free ligand, the
half-sandwich complex, and the cationic metallocene with its tetrachloridoscandate
counterion is observed via NMR spectroscopy. This equilibrium is fully
confirmed by 1H and 45Sc NMR EXSY experiments.
In the absence of coordinating solvents, the selective formation of
all compounds of the equilibrium has been achieved, and the structures
have been confirmed by NMR spectroscopy and X-ray structure analysis.
Especially 45Sc NMR spectroscopy reveals signals with characteristic
chemical shifts for the half-sandwich complex and the metallocene.
With scandium triflate the corresponding scandocene is also accessible.