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 -diketiminato ligand with the formula LRE(CH2SiMe3)(2)(thf) (RE = Y (1a), Dy (1b), Er (1c), Yb (1d); L = MeC(NDipp)CHC(Me)NCH2CH2NC4H2-2,5-Me-2, Dipp = 2,6-(Pr2C6H3)-Pr-i) were synthesized via the reactions of the -diketimine HL with the rare-earth metal trialkyl complexes RE(CH2SiMe3)(3)(thf)(2) 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(2) and sp(3) C-H bonds occurred during the reactions with pyridine derivatives to afford different types of mononuclear rare-earth metal pyridyl complexes, namely, LEr(CH2SiMe3)(2)((1)-NC5H4) (2c), LRE((3)-CH2-2-NC5H2-4,6-Me-2)(2) (RE = Y (3a), Er (3c)), and LRE(CH2SiMe3)((2)-(C,N)-2-(2-C6H4NC5H4)) (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(CH2SiMe3)(-C?CPh)](2) (5c). The mixed amidinate--diketiminato ytterbium complex LYb[(Dipp)NC(CH2SiMe3)N(Dipp)](CH2SiMe3) (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 CH2SiMe3 moiety with bis(2,6-diisopropylphenyl)formamidine to afford the erbium complex LEr(DippNCHNDipp)(CH2SiMe3) (7c). A rare sp(2) C-H bond oxidation of the -diketiminato backbone with elemental sulfur insertion was detected to provide the unprecedented dinuclear rare-earth metal thiolate complexes (LRE)(2)(-SCH2SiMe3)(2)(-SCC(Me)(NDipp)C(Me)NCH2CH2NC4H2Me2-2,5) (RE = Y (8a), Er (8c)) in the reactions of S-8 with 1a and 1c, respectively. The molecular structures of the complexes 1-8 were determined by single-crystal X-ray diffraction analyses.