Synthesis and reactivity of organogroup 3 complexes supported by beta-diketiminato ligands

A series of monomeric, low-coordinate yttrium bis-alkyl complexes supported by 2,6-substituted N-aryl beta -diketiminato ligand ancillaries have been synthesized and fully characterized in both the solid and solution state. Structural features and solution behaviour are examined in comparison to analogous scandium complexes. The yttrium bis-alkyl complexes exhibit moderate stability at room temperature but are susceptible to metalative decomposition via an established mechanism. Hydroamination experiments demonstrated the competency of the bis-alkyl compounds as catalysts for intramolecular ring closing of an amino-olefin substrate.;The neutral yttrium bis-alkyls were converted to cationic alkyl complexes via both alkide abstraction and protonolysis. While not isolable, these cations were extensively characterized in solution. With sterically bulky ligands, the alkyl cations are highly thermally sensitive and decompose via metalation pathways at ambient temperatures. Use of a smaller ancillary affords alkyl cations stabilized by arene coordination of N,N-dimethylaniline or dimerization. One cationic yttrium benzyl complex exhibits higher catalytic activity for olefin hydroamination than its neutral precursor, but others are not stable under catalytic conditions.;The spectroscopic characterization and derivatization of a compound previously characterized as a terminal imidoscandium complex (with a new 3,5-substituted N-aryl beta-diketiminato ligand) was undertaken. Variable temperature NMR spectroscopy and reactivity studies challenge the originally proposed structure. Alternative approaches to generate an imidoscandium complex via steric promotion or deprotonation were unsuccessful. A new scandium bis-alkyl was synthesized in attempt to prepare a more crystalline derivative of the previously reported imidoscandium species. Solid state structures of organoscandium complexes bearing 3,5-substituted N-aryl beta-diketiminato ligands were compared to evaluate the ligands' relative steric influence at the metal.;Preliminary studies establish that 3,5-substituted N-aryl beta -diketiminato organoyttrium complexes can be prepared via alkane elimination. The first example of alkane elimination from ancillary ligand-free yttrium alkyl cations with protonated ligands is presented.