Facile Construction of Yttrium Pentasulfides from Yttrium Alkyl Precursors: Synthesis, Mechanism, and Reactivity

Abstract

Treatment of the yttrium dialkyl complex Tp^Me2Y­(CH₂Ph)₂­(THF) (Tp^Me2 = tri­(3,5 dimethylpyrazolyl)­borate, THF = tetrahydrofuran) with S₈ in a 1:1 molar ratio in THF at room temperature afforded a yttrium pentasulfide Tp^Me2Y­(κ₄-S₅) (THF) (<b>1</b>) in 93% yield. The yttrium monoalkyl complex Tp^Me2CpYCH₂Ph­(THF) reacted with S₈ in a 1:0.5 molar ratio under the same conditions to give another yttrium pentasulfide [(Tp^Me2)₂Y]⁺­[Cp₂Y­(κ₄-S₅)]⁻ (<b>10</b>) in low yield. Further investigations indicated that the S₅^2– anion facilely turned into the corresponding thioethers or organic disulfides, and released the redundant S₈, when it reacted with some electrophilic reagents. The mechanism for the formation of the S₅^2– ligand has been investigated by the controlling of the reaction stoichiometric ratios and the stepwise reactions