Bis(dicyclohexylselenophosphinyl)selenide, [Cy₂P(Se)]₂Se: Synthesis, molecular structure and application for self-assembly of a tetrahedral Cu(I) cluster

The molecular structure of the selenides of [R₂P(Se)]₂Se type has been systematically studied on example of bis(dicyclohexylselenophosphinyl)selenide, [Cy₂P(Se)]₂Se. This selenide has been synthesized in 65% yield by oxidation of Cy₂PH with elemental selenium in 1:2 M ratio. Its structure has been investigated by X-ray diffractometry (XRD), NMR, FT-IR and MALDI-TOF/MS techniques. In the solid, the Se¹–P–Se²–P–Se³ chain of (Cy₂P = Se)₂Se molecule adopts a syn-anti conformation with the Se¹–P–Se²–P and P–Se²–P–Se³ torsion angles of −179.64 (3)° and 4.69 (4)°. The vibrational band assignments, performing at B3LYP/6-311++G (d,p) theory level, are in a good agreement with the experimental FT-IR frequencies. The synthetic utility of the prepared selenide has been exemplified by its reaction with CuCl₂ resulted in the formation of [Cu₄(Se₂PCy₂)₄] cluster in 53% yield. The structure of latter is formed by a Cu₄ tetrahedron, wherein each triangular face is bridged by a [Se₂PCy₂] ligand in a trimetallic triconnective (μ², μ¹) pattern.