Synthesis and derivatization of homoleptic dinuclear lanthanide siloxide complexes

摘要

Homoleptic dinuclear lanthanide siloxide complexes [Ln(OSitBuPh(2))(2)(mu-OSitBuPh(2))](2) (Ln = Y (1a), La (1b)), [Ln(OSiHtBu(2))(2)(mu-OSiHtBu(2))](2) (Ln = Y (2a), La (2b), Nd (2c), Lu (2d)), and {Ln[OSi(OtBu)(3)](2)[mu-OSi(OtBU)(3)]}(2) (Ln = Y (3a), La (3b)) were synthesized according to the silylamide route in yields between 67 and 92%. Their bis(siloxide)-bridged molecular arrangement was proven by variable temperature H-1 NMR spectroscopy as well as by an Xray structure analysis of 2c. The IR spectra of complexes 2 feature low-energy Si-H stretching vibrations (1965-1915 cm(-1)) indicative of beta(Si-H)...Ln agostic interactions. Complexes 2 and 3 readily form monomeric bis(donor) adducts with tetrahydrofurane, triphenylphosphine oxide, and N-methylimidazol as shown for fully characterized Ln(OSiHtBu(2))(3)(thf)(2) (Ln = Y (4a), La (4b)), Y(OSiHtBu(2))(3)(OPPh3)(2) (5), Ln(OSiHtBu(2))(3)(N-MeIM)(2) (Ln = Y (6a), La (6b)), and Y[OSi(OtBU)(3)](3)(thf)(2) (7). Treatment of complexes 1-3 with excess of trimethylaluminum, (TMA) generated several alkylated rare-earth metal species including homoleptic Ln(AlMe4)(3) as indicated by H-1 NMR spectroscopy. La[OSi(OtBu)(3)](AlMe4)(2)(AlMe3) (8b) was isolated by crystallization and analyzed by X-ray diffraction.