Reactivity of halfsandwich rare-earth metal methylaluminates toward potassium (2,4,6-tri-tert-butylphenyl)amide and 1-adamantylamine

Abstract

The equimolar reaction of potassium (2,4,6-tri-tert-butylphenyl)amide with Cp*Ln(AlMe₄)₂ (Cp* = 1,2,3,4,5-pentamethyl cyclopentadienyl) yielded {Cp*Ln(AlMe₄)[NH(mes*)]}_x (Ln = Y, La; mes* = C₆H₂tBu₃-2,4,6). The treatment of Cp*Ln(AlMe₄)[NH(mes*)] with tetrahydrofuran led to intramolecular C–H bond activation of a tBu group with the formation of Cp*YMe{NH[C₆H₂tBu₂-2,4-(CMe₂CH₂)-6]}(AlMe₂)(thf). A similar methyl-anilide species Cp^QLuMe{NH[C₆H₂tBu₂-2,4-(CMe₂CH₂)-6]}(AlMe₂) (Cp^Q = 2,3,4,5-tetramethyl-1-(8-quinolyl)cyclopentadienyl) with a C–H bond activated ligand backbone formed by the reaction of Cp^QLu(AlMe₄)₂ and K[NH(mes*)]. The reactivity of Cp^QY(AlMe₄)₂ toward H₂NAd (Ad = adamantyl) ultimately led to the methyl–amide complex Cp^QYMe[NH(Ad)](AlMe₃), corroborating the presence of competing deprotonation and donor-induced methylaluminate cleavage reactions. The halfsandwich complexes Cp^QLu(AlMe₄)₂, Cp*Y(AlMe₄)[NH(mes*)], Cp*YMe{NH[C₆H₂tBu₂-2,4-(CMe₂CH₂)-6]}(AlMe₂)(thf), Cp^QLuMe{NH[C₆H₂tBu₂-2,4-(CMe₂CH₂)-6]}(AlMe₂), and Cp^QYMe[NH(Ad)](AlMe₃) as well as the side-product AlMe₃(H₂NAd) were fully characterized by NMR/FTIR spectroscopy, elemental analysis, and X-ray crystallography.