As–As Bond Formation via Reductive Elimination from a Zirconocene Bis(dimesitylarsenide) Compound

A new zirconocene bis­(arsenide) derivative, Cp2Zr­(AsMes2)2 (1; Cp = cyclopentadienyl, Mes = 2,4,6-trimethylphenyl), has been prepared by the metathetical reaction of 2 equiv of LiAsMes2 with Cp2ZrCl2 and structurally characterized. Efforts to prepare Cp2ZrCl­(AsMes2) (2) by reaction of 1 equiv of LiAsMes2 with Cp2ZrCl2 yielded a mixture of products that could not be separated, including 1 and 2, as identified by 1H NMR spectroscopy. Compound 1 thermally decomposes with formation of As2Mes4, suggestive of reductive elimination to form an As–As bond. Further evidence for reductive elimination comes from effective interception of a putative zirconium­(II) intermediate with diphenylacetylene to give Cp2Zr­(C4Ph4).