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

Abstract

Three organometallic rhenium-based clusters containing phenylacetylide ligands, [Re 6 Se 8 (PEt 3 ) 5 (C�C−Ph)]-(SbF 6 ) (1) and cis-and trans-[Re 6 Se 8 (PEt 3 ) 4 (C�C−Ph) 2 ] (2 and 3), were synthesized and fully characterized including singlecrystal 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 r e a c t i o n s , i n c l u d i n g t h e m e t h y l s u l f a t e c o m p l e x , [Re 6 Se 8 (PEt 3 ) 5 (OSO 3 Me)](SbF 6 ) (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 [Re 6 Se 8 ] 2+ −acetylide bond and aid in our understanding of the reactivity associated with this cluster complex.