Rhenium Selenide Clusters Containing Alkynyl Ligands: Unexpected Reactivity of Σ-Bound Phenylacetylide

Three organometallic rhenium-based clusters con-taining phenylacetylide ligands, [Re6Se8(PEt3)5(C-C-Ph)]-(SbF6) (1) and cis-and trans-[Re6Se8(PEt3)4(C-C-Ph)2] (2 and 3), were synthesized and fully characterized including single -crystal X-ray diffraction analyses. Reactivity studies of 1 show that reaction with electrophilic reagents does not result in the formation of the vinylidene species as predicted; instead, elimination of the acetylide moiety is observed. Products isolated from these reactions, including the methyl sulfate complex, [Re6Se8(PEt3)5(OSO3Me)](SbF6) (4), have been characterized along with those obtained from the [2 + 2] cycloadditions of 1 with tetracyanoethylene and 7,7,8,8-tetracyanoquinodimethane. The relative reactivities of the electrophilic agents utilized are compared. Preliminary computational studies reveal useful information about the nature of the [Re6Se8]2+-acetylide bond and aid in our understanding of the reactivity associated with this cluster complex.

Automated summary

Three rhenium-based clusters with phenylacetylide ligands were synthesized and characterized. Reactivity studies showed that the formation of the predicted vinylidene species did not occur, and instead, elimination of the acetylide moiety was observed. Characterization of the reaction products and computational studies provided insights into the reactivity of this cluster complex.