Deprotonation of β-Diketiminate in Sterically Demanding β-(Diketiminato)lanthanide Complexes: Influence of Lanthanide Metals

Attempted synthesis of tris(β-diketiminato)lanthanide complexes [Ln(L)3] (L = [{N(C6H3Me2-2,6)C(Me)}2CH]) resulted in ligand deprotonation, and different outcomes depending on the central metal used were observed. Reaction of YbCl3 with NaL (3 equiv.) afforded the five-membered cyclometalated ytterbium β-diketiminate complex [Yb(L)(L)dep] (1). The same reaction with LnCl3 (Ln = Nd, Sm, and Er) gave the new complexes composed of one normal L and one deprotonated neighboring benzazacyclopentane ligand derived from deprotonation of the 2-methyl group followed by an attack of thecarbon atom on the β-diketiminate backbone, [Ln(L)(L)dep′(thf)] [Ln = Nd (2), Sm (3), and Er (4)]. The bonding mode in the {Ln(L)dep′} moiety was also found to depend on the central metal ions.