Reactivity of Organolanthanide Derivatives Containing the o-Aminothiophenolate Ligand toward Carbodiimide

A series of lanthanocene derivatives containing the o-aminothiophenolate ligand have been synthesized, and their reactivities toward carbodiimide have been investigated. Reaction of N,N‘-diisopropylcarbodiimide (ⁱPrNCNⁱPr) with [Cp₂Yb(o-H₂NC₆H₄S)]₂·2THF (Cp = C₅H₅) (1) yields a centrosymmetric dimer, [Cp(THF)Yb(μ-η³:η¹-SC₆H₄NC(NHⁱPr)NⁱPr)]₂ (2), indicating that the adjacent NH₂ group can add to the CN double bonds of carbodiimide and one cyclopentadienyl group is eliminated. [Cp₂Dy(o-H₂NC₆H₄S)]₂·3THF, obtained by protolysis of Cp₃Ln with o-aminothiophenol, reacts with 2 or 1 equiv of ⁱPrNCNⁱPr in THF at room temperature to give the partial amino group addition product CpDy(THF)[μ-η³:η¹-SC₆H₄NC(NHⁱPr)NⁱPr)](μ-η²:η¹-SC₆H₄NH₂)DyCp₂·THF (4). When Cp₃Dy reacts with o-aminothiophenol, and subsequently with ⁱPrNCNⁱPr in toluene at room temperature, we isolated complex 4 and a small amount of [Cp₂Dy(o-H₂NC₆H₄S)]₂·2THF (5) and [Cp(THF)Dy(μ-η³:η¹-SC₆H₄NC(NHⁱPr)NⁱPr)]₂ (6). Treatment of 2 equiv of ⁱPrNCNⁱPr with 3 in THF under reflux temperature also gave 4; the residual NH₂ group cannot continuously add into the CN bonds of other carbodiimide molecules. Reaction of Cp₃Er with 2 equiv of o-aminothiophenol and subsequently with 2 equiv of ⁱPrNCNⁱPr in THF at room temperature yields the bis-addition product (C₅H₅)Er[SC₆H₄NC(NHⁱPr)₂]₂ (7). However, when Cp₃Er reacts with 2 equiv of o-aminothiophenol, and subsequently with 1 equiv of ⁱPrNCNⁱPr, the organic disulfide (ⁱPrHN)₂CNC₆H₄SSC₆H₄NC(NHⁱPr)₂ (8) can be isolated. These results indicate that the addition of the adjacent amino group into the CN double bonds of the carbodiimide molecule is strongly affected by the metal ion character and the steric hindrance of the ligands. All of the new compounds have been characterized by elemental analysis and spectroscopic properties. Their structures have also been determined through X-ray single-crystal diffraction analysis.