Low-Coordinate Mixed Ligand NacNac Complexes of Rare Earth Metals

We report the synthesis and characterization of two types of new mixed-ligand rare earth complexes: tetracoordinate (NacNac(Mes))Ln(BIAN(dipp)) (Ln = Dy (1), Er (2) and Y (3)) and pentacoordinate (NacNac(Mes))Ln(AP(dipp))(THF) (Ln = Dy (4), Er (5) and Y (6)). The first three compounds were prepared by the reaction of [(BIAN(Dipp))LnI] with potassium β-diketiminate. The salt metathesis of β-diketiminato-supported rare earth dichlorides (NacNac(Mes))LnCl(2)(THF)(2) with sodium o-amidophenolate results in compounds 4–6. The crystal structures of complexes 1–6 were determined by single-crystal analysis. The combination of bulky monoanionic N-mesityl-substituted β-diketiminates with sterically hindered redox-active ligands led to the very low coordination numbers of rare earths and strong distortion of the chelate ligands.