Lewis-Acid Stabilized Organoimide Complexes of Divalent Samarium, Europium, and Ytterbium.

Discrete organoimide complexes of the divalent rare-earth metals samarium, europium, and ytterbium are reported. Tandem salt metathesis-protonolysis reactions using LnII bis(tetramethylaluminate) precursors [Ln(AlMe4 )2 ]n and monopotassium salts of 2,6-diisopropylaniline (H2 NDipp) and triphenylsilylamine prove viable and efficient protocols. Depending on the ionic radius of the LnII metal centers and the steric demand of the imido carbon backbone, mono- and dilanthanide arrangements of general composition [(thf)x Ln(NR)(AlMe3 )]y (Ln=Sm, Eu, Yb; R=Dipp, SiPh3 ) are found in the solid state. Complex formation and stabilization is achieved by coordination of the Lewis acid AlMe3 , which also prevents formation of higher aggregated species. The feasibility of redox chemistry is shown with the plumbocene derivative Cp*2 Pb, providing access to the corresponding monomeric LnIII half-sandwich complexes [Cp*Ln(NR)(AlMe3 )(thf)2 ] (Ln=Sm, Yb).