Rich C–H bond activations of yttrium alkyl complexes bearing phosphinimino-amine ligands

A series of phosphinimino-amine compounds (2,6–iPr2–C6H3NH)C(Me)CHPPh2(NAr) (Ar = 2,6–iPr2–C6H3 (HL1), 2,6–Et2–C6H3 (HL2), 2,6–Me2–C6H3 (HL3), C6H5 (HL4), 3–CF3–C6H4 (HL5)) that existed in imine and amine forms were synthesized and fully characterized. Treatment of HL1−5 with Y(CH2SiMe3)3(THF)2 afforded the corresponding yttrium mono- or bis(alkyl) complexes that depended significantly on the ancillary ligands. The reactions between HL1−3 and Y(CH2SiMe3)3(THF)2 at room temperature generated mononuclear monoalkyl complexes 1–3 via deprotonation and C–H bond activation. However, when compounds HL4,5 were used, the dialkyl complexes 4 and 5 were isolated by deprotonation only. The molecular structures of complexes 1–4 were characterized with X-ray crystallography and discussed.

Graphical abstractThe reactions between HL1−3 and Y(CH2SiMe3)3(THF)2 generated mono(alkyl) complexes 1, 2, and 3 via deprotonation and C–H bond activation. However, when compounds HL4,5 were used, the dialkyl complexes 4 and 5 were formed by deprotonation. The activation position correlated with the steric bulkiness of aryl substituents of phosphinimino moiety.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► A series of new yttrium mono- and dialkyl complexes bearing the phosphinimino-amine ligands are synthesized. ► The C–H bond activation occurs. ► The structural variation of the ligand influences the C–H bond activation.