Rare-Earth Metal Diimide Complexes via Alkylaluminate Templating, Including a Ceric Derivative.

Protonolysis of lanthanide tris(tetramethylaluminate)s with two equivalents of 2,6-diisopropylaniline affords LaIII and CeIII diimide compounds Ln[(μ-NC6 H3 iPr2 -2,6)2 AlMe2 ](thf)4 featuring a bidentate AlMe2 -linked diimido ligand. As revealed for the corresponding Ce(GaMe4 )3 -reaction, formation of the diimide complexes proceeds via tetrametallic complexes of the type [Ce{(μ-NC6 H3 iPr2 -2,6)(HNC6 H3 iPr2 -2,6)(MMe3 )}]2 (Me=Al, Ga). Oxidation of the cerium(III) complex with hexachloroethane leads to a neutral CeIV diimide species. Partial protonolysis with phenylacetylene and hydrogenolysis via H3 SiPh give conclusive insights into the reactive coordination sites of such diimide complexes.