Cationic organometallic compounds of electropositive metals have been identified as key intermediates in important catalytic processes, such as (stereo)selective olefin oligome-rization and (co)polymerization. They also show unique reactivity patterns in stoichiometric reactions. Thus, catio-nization as a means of controlling reactivity is well established for compounds of Lewis acidic tri- and tetravalent Group 3,4, and 13 metals, and the lanthanoids. In contrast, cationic organometallic complexes of nontoxic and abundant divalent Group 2 and 12 metals have only recently been described. In the case of organozinc compounds, few monocations have been applied as selective catalysts in lactide, lactone, and epoxide polymerization,as well as in hydrosilyla-tionsand hydroaminations.We report herein the isolation and full characterization of the allylzinc monocation, which—in contrast to its neutral parent compound bis-(allyl)zinc—allows for efficient coupling of allyl anions in a highly selective metallo-ene reaction.
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