Unusual modification methods for the ureido ligand of lanthanocene derivatives

Abstract

(C₅H₅)₂Ln[OC(PzMe₂)NPh](THF) (Ln = Dy (1a), Er (1b), Yb (1c), Y (1d)) were prepared in good yields by the PhNCO insertion into the Ln–N bond of (C₅H₅)₂Ln(PzMe₂)(THF) (PzMe₂ = 3,5-dimethylpyrazolate) in THF at room temperature. Treatment of 1 with p-aminothiophenol in THF at room temperature gives unusual ligand-based substitution derivatives {(C₅H₅)₂Ln[μ-η¹:η³-OC(p-H₂NC₆H₄S)NPh]}₂·2THF (Ln = Dy (2a), Er (2b), Yb (2c), Y (2d)), while reaction of 1c with o-aminothiophenol instead of p-aminothiophenol allows the occurrence of a tandem substitution/cyclization/elimination to form unexpected benzothiazole-2-oxide complex [(C₅H₅)₂Yb(μ-η¹:η³-OSNC₇H₄)]₂ (3c), representing a novel modification method for non-cyclopentadienyl ligands of lanthanocene derivatives. However, complex 1c does not react with benzyl thiol, indicating that the nature of thiols has a profound influence on the substitution reaction. All complexes were characterized by elemental analysis and spectroscopic properties. The X-ray diffraction analysis reveals that 1a and 1b are solvated monomeric structures, while 2a and 2d are centrosymmetric dimeric ones with an unusual intermolecular hydrogen bond interaction involving THF.