Versatile reactivities of rare-earth metal dialkyl complexes supported by a neutral pyrrolyl-functionalized β-diketiminato ligand.

Herein, rare-earth metal dialkyl complexes supported by a neutral pyrrolyl-functionalized β-diketiminato ligand with the formula LRE(CHSiMe)(thf) (RE = Y (1a), Dy (1b), Er (1c), Yb (1d); L = MeC(NDipp)CHC(Me)NCHCHNCH-2,5-Me, Dipp = 2,6-PrCH) were synthesized via the reactions of the β-diketimine HL with the rare-earth metal trialkyl complexes RE(CHSiMe)(thf) in high yields. The reactivities of 1 with pyridine derivatives, unsaturated substrates, and elemental sulfur were investigated, and some interesting chemical transformations were observed. Ligand exchange and activation of sp and sp C-H bonds occurred during the reactions with pyridine derivatives to afford different types of mononuclear rare-earth metal pyridyl complexes, namely, LEr(CHSiMe)(η-NCH) (2c), LRE(η-CH-2-NCH-4,6-Me) (RE = Y (3a), Er (3c)), and LRE(CHSiMe)(η-(C,N)-2-(2-CHNCH)) (RE = Er (4c), Yb = (4d)). Similarly, activation of the sp C-H bond occurred during the reaction of phenylacetylene with 1c to produce the dinuclear erbium alkynyl complex [LEr(CHSiMe)(μ-C[triple bond, length as m-dash]CPh)] (5c). The mixed amidinate-β-diketiminato ytterbium complex LYb[(Dipp)NC(CHSiMe)N(Dipp)](CHSiMe) (6d) was obtained by the insertion of bis(2,6-diisopropylphenyl)carbodiimide into a Yb-alkyl bond, as well as via the direct alkane elimination of a CHSiMe moiety with bis(2,6-diisopropylphenyl)formamidine to afford the erbium complex LEr(DippNCHNDipp)(CHSiMe) (7c). A rare sp C-H bond oxidation of the β-diketiminato backbone with elemental sulfur insertion was detected to provide the unprecedented dinuclear rare-earth metal thiolate complexes (LRE)(μ-SCHSiMe)(μ-SCC(Me)(NDipp)C(Me)NCHCHNCHMe-2,5) (RE = Y (8a), Er (8c)) in the reactions of S with 1a and 1c, respectively. The molecular structures of the complexes 1-8 were determined by single-crystal X-ray diffraction analyses.