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 Ln bis(tetramethylaluminate) precursors [Ln(AlMe ) ] and monopotassium salts of 2,6-diisopropylaniline (H NDipp) and triphenylsilylamine prove viable and efficient protocols. Depending on the ionic radius of the Ln metal centers and the steric demand of the imido carbon backbone, mono- and dilanthanide arrangements of general composition [(thf) Ln(NR)(AlMe )] (Ln=Sm, Eu, Yb; R=Dipp, SiPh ) are found in the solid state. Complex formation and stabilization is achieved by coordination of the Lewis acid AlMe , which also prevents formation of higher aggregated species. The feasibility of redox chemistry is shown with the plumbocene derivative Cp* Pb, providing access to the corresponding monomeric Ln half-sandwich complexes [Cp*Ln(NR)(AlMe )(thf) ] (Ln=Sm, Yb).