Reactivity of Scorpionate-Anchored Yttrium Alkyl Primary Amido Complexes toward Carbodiimides. Insertion Selectivity of Y–NHAr and Y–CH2Ph Bonds

The TpMe2-supported yttrium dialkyl TpMe2Y­(CH2Ph)2(THF) (TpMe2 = tri­(3,5-dimethylpyrazolyl)­borate) reacted with 1 equiv of ArNH2 in THF at room temperature to afford the yttrium alkyl primary amido complexes TpMe2YNHAr­(CH2Ph)­(THF) (Ar = Ph (1), C6H3-iPr2-2,6 (2)) in 84% and 88% isolated yields, respectively. Complex 1 reacted with iPrNCNiPr in THF at room temperature to give a yttrium dianionic guanidinate complex, TpMe2Y­[(iPrN)2CNPh]­(THF)2 (3, 74%). However, the reaction of 1 with ArNCNAr (Ar = C6H3-iPr2-2,6) in the same conditions produced a Y–C bond insertion product, TpMe2Y­[(ArN)2CCH2Ph]­(NHPh) (4, 87%). Moreover, treatment of 2 with 1 equiv of iPrNCNiPr in THF at room temperature afforded two yttrium complex, TpMe2Y­[(iPrN)­CNAr]­(THF) (5) and TpMe2Y­[(iPrN)2CCH2Ph]­(NHAr) (6), in 58% and 19% isolated yields, respectively. These results indicated that carbodiimide can selectively insert into the Y–CH2Ph and Y–NHAr σ-bonds of TpMe2-supported yttrium alkyl primary amido complexes TpMe2YNHAr­(CH2Ph)­(THF), and this selectivity depends on the steric hindrance of the substituent groups R of cabodiimides and the primary amido ligands. All these new complexes were characterized by elemental analysis and spectroscopic methods, and their solid-state structures except 1 were also confirmed by single-crystal X-ray diffraction analysis.