First examples of stable transition metal complexes of an all-metal antiaromatic molecule (Al₄Li₄)

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We propose new methodologies for stabilizing all-metal antiaromatic clusters like: Al₄Li₄. We demonstrate that these all-metal species can be stabilized by complexation with 3d-transition metals very similar to its organic counterpart, C₄H₄. Complexation to transition metal ions reduce the frontier orbital energies and introduces aromaticity. We consider a series of such complexes [η⁴(Al₄Li₄)-Fe(CO)₃, η²σ²(Al₄Li₄)-Ni and (Al₄Li₄)₂Ni] and make a comparison between the all-metal species and the organometallic compounds to prove conclusively our theory. Fragmentation energy analysis as well as NICS support similar mechanism of complexation induced stability in these all-metal molecules.