Synthesis and characterization of β-diketiminate lanthanide complexes:: the effect of the bulkiness of ancillary ligand on the reaction

The reactions of ytterbium dichlorides with different beta-diketiminate ligand ((Ar)NC(Me)CHC(Me)N(Ar), Ar = Ar' = C6H5 (L-1); Ar = Ar' = 2,6-Me-2-C6H3 (L-2); Ar = C6H5, Ar' = 2, 6-Pr-2(i)-C6H3 (L-3)) with I equiv of Cp'Na were studied. It was found that the bulkiness of beta-diketiminate ligand and cyclopentadienyl group both have significant effect on the above reaction. For less bulky ligands L-1 and L-2, the reaction affords not the expected mixed-ligand ytterbium chloride, (C5H5)YbLCl or (CH3C5H4)YbCl, but the 3 ligand-redistributed product (C5H5)(2)YbL or (CH3C5H4)(2)YbL. For bulkier ligand L-3, the desired anionic ytterbium chloride (C5H5)YbL3(mu-Cl)(2)Li(THF)(2) is obtained. For the smallest ligand L-1, the expected ytterbium monochloride can also be obtained using bulky C5Me5Na as reactant. Each of these complexes was well characterized, while several have been characterized by X-ray diffraction structure determination. (C) 2003 Elsevier B.V. All rights reserved.