Synthesis and photophysical properties of rare earth complexes bearing silanediamido ligands Me2Si(NAryl)22− (Aryl = Dipp, Mes)

Abstract

A series of rare earth (RE) chloride complexes bearing silanediamido ligands (L^Aryl)²⁻ = Me₂Si(NAryl)₂²⁻ with bulky substituents, Aryl = mesityl (Mes), and 2,6-diisopropylphenyl (Dipp) was synthesized by salt metathesis reactions. Binuclear species [{RE(L^Aryl)(thf)₂}₂(μ-Cl)₂] (RE^Aryl; RE = Y, Gd, Tb, Sm, Aryl = Dipp; RE = Y, Gd, Tb, Aryl = Mes) crystallize from non-polar solvents. Deprotonation reactions of proligands H₂L^Aryl by KH and n-BuLi are compared, and the advantages of both approaches are discussed. Formation of ate complexes [{RE(L^Aryl)(thf)(μ-Cl)₂Li(thf)₃}₂(μ-Cl)₂] (RE = Y, Tb) was detected when using n-BuLi. Recrystallization of Y^Dipp from pure thf led to the monomerization to the [Y(L^Dipp)Cl(thf)₃] complex. Energies of the triplet states were determined for both ligands from the photoluminescence (PL) spectra of Gd complexes. The PL of Tb complexes in the solid state and in a solution was studied, showing substantial sensitization by the (L^Aryl)²⁻ ligands.