Realgar as a Building Block for Lanthanide Clusters: Encapsulation of a Copper Cluster by a Lanthanide Cluster

Abstract

The reactions of the divalent lanthanide metallocenes [Cp*₂Ln­(thf)₂] (Cp* = η⁵-C₅Me₅; Ln = Sm, Yb) with realgar (As₄S₄) gave the open cage tetrametallic complex [(Cp*₂Sm)­(Cp*Sm)₃AsS₃(Cp*AsS₂)₂(thf)₃] (<b>1</b>) or the trimetallic cage compound [(Cp*Yb)₃As₂S₄(Cp*AsS₂)­(thf)₂] (<b>2</b>), respectively, by reductive cleavage of the inorganic cage. As result of a Cp* transfer, the novel Cp*AsS₂^2– anion is formed. Moreover, the As₂S₄^4– anion, which is bound in <b>2</b>, is observed for the first time in coordination chemistry. Closed cage compounds are formed by either using bulkier ligands or a different As/S cage. The reaction of [Cp‴₂Sm] (Cp‴ = (1,2,4-(<i>t</i>-Bu)₃C₅H₂)) with As₄S₄ and the reaction of [Cp*₂Yb­(thf)₂] with dimorphite (As₄S₃) gave the closed 11-vertex cage clusters [(Cp‴Sm)₃(AsS₃)₂] (<b>3</b>) and [(Cp*Yb)₃(AsS₃)₂] (<b>4</b>), respectively. The reaction of <b>3</b> with [CuMes] resulted in the formation of the Sm/S/Cu cluster [(Cp‴Sm­(thf))₄Cu₄S₆] (<b>5</b>), in which the Sm atoms encapsulate a classical Cu₄S₆^8– cluster core. This is the first transition metal chalcogenide cluster encapsulated by f-elements. Alternatively, the endohedral cluster can thus be described as [Cu₄@{(Cp‴Sm­(thf))₄S₆}], in which a Cu₄ tetrahedron is encapsulated by the samarium sulfido cluster {(Cp‴Sm­(thf))₄S₆}