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A Stable Neutral Compound with an Aluminum-Aluminum Double Bond
Prasenjit Bag1, Amelie Porzelt1, Philipp J Altmann1
1Department of Chemistry, Catalysis Research Center and Institute of Silicon Chemistry, Technische Universität München , Lichtenbergstraße 4, 85748 Garching bei München, Germany.
Abstract:
Homodinuclear multiple-bonded neutral Al compounds, aluminum analogues of alkenes, have been a notoriously difficult synthetic target over the past several decades. Herein, we report the isolation of a stable neutral compound featuring an Al═Al double bond stabilized by N-heterocyclic carbenes. X-ray crystallographic and spectroscopic analyses demonstrate that the dialuminum entity possesses trans-planar geometry and an Al-Al bond length of 2.3943(16) Å, which is the shortest distance reported for a molecular dialuminum species. This new species reacts with ethylene and phenyl acetylene to give the [2+2] cycloaddition products. The structure and bonding were also investigated by detailed density functional theory calculations. These results clearly demonstrate the presence of an Al═Al double bond in this molecule.
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