Reaction of Zirconocene–Carboryne with Alkenes: Synthesis and Structure of Zirconacyclopentanes with a Carborane Auxiliary

Reaction of zirconocene–carboryne in situ generated from Cp2Zr­(μ-Cl)­(μ-C2B10H10)­Li­(OEt2)2 with various alkenes RCHCH2 in refluxing toluene gave the monoinsertion products 1,2-[Cp2ZrCH­(R)­CH2]-1,2-C2B10H10 (R = aryl) or 1,2-[Cp2ZrCH2CH­(R)]-1,2-C2B10H10 (R = alkyl) in good to high isolated yields with very high regioselectivity, depending on the polarity of the alkenes. This reaction offered an efficient route to zirconacyclopentanes with a carborane auxiliary, which can be viewed as a carborane version of zirconacyclopentanes. They are thermally very stable and chemically inert toward unsaturated organic molecules such as alkenes, alkynes, nitriles, CO, and CO2. All complexes have been fully characterized by various spectroscopic techniques. Some have been further confirmed by single-crystal X-ray analyses.