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Visiting the Limits between a Highly Strained 1-Zirconacyclobuta-2,3-diene and Chemically Robust
Fabian Reiß1, Melanie Reiß1, Anke Spannenberg1
1Leibniz-Institut für Katalyse e.V. an der, Universität Rostock (LIKAT), Albert-Einstein-Strasse 29a, 18059, Rostock, Germany.
Abstract:
The reaction of the allene precursor Li2 (Me3 SiC3 SiMe3 ) with [Cp2 ZrCl2 ] (Cp=cyclopentadienyl) was examined. The selective formation of hitherto unknown linear, allene-bridged dizirconocene complexes [(Cp2 ZrCl)2 {-μ-(Me3 Si)C3 (SiMe3 )-}] and [(Cp2 Zr)2 {-μ-(Me3 Si)C3 (SiMe3 )-}2 ] was observed. Upon σ coordination of the allenediyl unit to {Cp2 Zr}, pyrophoric Li2 (Me3 SiC3 SiMe3 ) is tamed stepwise to yield a surprisingly robust 1,5-dizirconacyclooctatetra-2,3,6,7-ene with cumulated double bonds. This complex is unexpectedly inert against moisture, air, water and acetone. Surprisingly, it degrades under MS conditions to give the highly strained 1-zirconacyclobuta-2,3-diene. All compounds isolated have been fully characterised and the molecular structures are discussed. The stability and reactivity of these complexes are rationalised by DFT computations.
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