Synthesis and structural characterization of imido-lanthanide complexes with a metal-nitrogen multiple bond

Treatment of an amido-ytterbium complex with n-BuLi leads to the isolation and structural characterization of a mixed amido-imido-ytterbium or imido-ytterbium complex, respectively, depending upon the molar ratios of the reactants; the Yb-N distance and the linearity of the imido N atom strongly suggest the presence of a formal Yb=N multiple bond in these novel complexes.