Synthesis and Reactivity of NNNNN-Pincer Multidentate Pyrrolyl Rare-Earth-Metal Amido-Chloride or Dialkyl Complexes

The NNNNN-pincer multidentate pyrrolyl rare-earth-metal amido-chloride complexes {η¹:κ³-2,5-[CH₃N­(CH₂CH₂)₂NCH₂]₂C₄H₂N}­RECl­[N­(SiMe₃)₂] (RE = Y (2a), Sm (2b), Dy (2c), Er (2d), Yb (2e)) were synthesized by one step from reactions of [(Me₃Si)₂N]₃RE­(μ-Cl)­Li­(THF)₃ with {2,5-[CH₃N­(CH₂CH₂)₂NCH₂]₂}­C₄H₂NH (1). Reactions of compound 1 with RE­(CH₂SiMe₃)₃(THF)₂ gave the rare-earth-metal dialkyl complexes {η¹:κ²-2,5-[CH₃N­(CH₂CH₂)₂NCH₂]₂C₄H₂N}­Sc­(CH₂SiMe₃)₂ (3a) and {η¹:κ³-2,5-[CH₃N­(CH₂CH₂)₂NCH₂]₂C₄H₂N}­RE­(CH₂SiMe₃)₂ (RE = Y (3b), Dy (3c), Er (3d), Yb (3e), Lu (3f)). Further reactions of complexes 3 with dimethylaniline afforded rare-earth-metal diamido complexes bearing an NNNNN-pincer multidentate pyrrolyl ligand, but not rare-earth-metal imido complexes even under the condition of additional DMAP. All complexes were characterized by spectroscopic methods, elemental analyses, and single-crystal X-ray diffraction. The pincer multidentate pyrrolyl rare-earth-metal dialkyl complexes showed high catalytic activities for the addition of amines to carbodiimides or isothiocyanate to afford the substituted guanidines and thioureas.