Rare-Earth Metal Alkyl, Amido, and Cyclopentadienyl Complexes Supported by Imidazolin-2-iminato Ligands: Synthesis, Structural Characterization, and Catalytic Application

The rare earth metal dichlorides [(1)MCl2(THF)3] (2a, M = Sc; 2b, M = Y; 2c, M = Lu) and the gadolinium complex [(1)GdCl2(THF)2]·[LiCl(THF)2] (2d), containing the 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-iminato ligand 1, proved to be versatile starting materials for the preparation of trimethylsilylmethyl (“neosilyl”) and bis(trimethylsilyl)amido complexes [(1)M(CH2SiMe3)2(THF)2] (3a−3d) and [(1)M(HMDS)2(THF)] [4a−4d, HMDS = hexamethyldisilazide, N(SiMe3)2] and for the preparation of the benzyl complex [(1)Lu(CH2Ph)2(THF)2] (5c) by the reaction with LiCH2SiMe3, Na[N(SiMe3)2], and KCH2Ph, respectively. Treatment of 2a−2c with KCp* afforded the mono(pentamethylcyclopentadienyl) complexes [(1)Sc(Cp*)Cl(THF)] (6a), [(1)Y(Cp*)Cl(THF)2] (6b), and [(1)Lu(Cp*)Cl(THF)] (6c). In contrast, the gadolinocene complex [(1)Gd(Cp*)2(THF)] (7) was isolated from the reaction of 2d with 2 equiv of KCp*. The molecular structures of 3a−3d, 4b·THF, 4d, 5c, 6a, 6c, and 7·THF were determined by X-ray diffraction analyses, revealing the presence of exceptionally short metal−nitrogen bonds. The neosilyl complexes 3b and 3c showed high catalytic activity in the intramolecular hydroamination of aminoalkenes and aminoalkynes and in the hydrosilylation of 1-hexene and 1-octene with PhSiH3.