Lanthanide Amide Complexes Supported by the Bis‐tris(pyrazolyl)borate Ligand Environment

The specific synthetic conditions to successfully access primary lanthanide amides in the bis-hydrotris(1-pyrazolyl)borate ligand environment [Ln(Tp)₂(NHAr^CF3)] 3-Ln (Ln=Y, Dy; Ar^CF3=C₆H₃(CF₃)₂-3,5) are reported by either metathesis of [Ln(Tp)₂(OTf)] 1-Ln (OTf=CF₃SO₃) with K(NHAr^CF3) or protonolysis of [Ln(Tp)₂(N′′)] 2-Ln (N′′=N(SiMe₃)₂) with H₂NAr^CF3 in toluene.

Abstract

Synthesis of primary lanthanide amides in the bis-hydrotris(1-pyrazolyl)borate ligand environment has been achieved. Salt metathesis of [Dy(Tp)₂(OTf)] 1-Dy (OTf=CF₃SO₃) with K(N′′) (N′′=N(SiMe₃)₂) in toluene yielded the [bis(silyl)]amide [Dy(Tp)₂(N′′)] 2-Dy. Complexes 1-Ln and 2-Ln were both used to access primary lanthanide amides, where either metathesis of 1-Ln with K(NHAr^CF3) (Ar^CF3=C₆H₃(CF₃)₂-3,5) or protonolysis of 2-Ln with H₂NAr^CF3 in toluene yielded [Ln(Tp)₂(NHAr^CF3)] 3-Ln (Ln=Y, Dy). The synthesis of parent amides was also attempted, but the metathesis of 1-Y with NaNH₂ yielded complicated reaction mixtures, but from which the dimeric parent amide [{Y(Tp)₂(μ-NH₂)}₂] 4-Y and an ‘ate’-salt [{Y(Tp)₂(μ ₂-OTf)(μ ₃-OTf)Na(THF)₂}₂] 5-Y were isolated. Full characterisation data are presented for all complexes, including the structure determination.

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