First examples of stable transition metal complexes of an all-metal antiaromatic molecule (Al$_4$Li$_4$)

TL;DR

This paper introduces methods to stabilize all-metal antiaromatic clusters like Al$_4$Li$_4$ by complexation with transition metals, demonstrating induced aromaticity and stability through computational analysis.

Contribution

It presents the first examples of stable transition metal complexes of an all-metal antiaromatic molecule, showing how complexation induces aromaticity and stability.

Findings

Complexation reduces frontier orbital energies.

NICS calculations support aromaticity induction.

Comparison with organic analogs confirms the stabilization mechanism.

Abstract

We propose new methodologies for stabilizing all-metal antiaromatic clusters like: Al$_{4}$Li$_{4}$. We demonstrate that these all-metal species can be stabilized by complexation with 3d-transition metals very similar to its organic counterpart, C$_4$H$_4$. Complexation to transition metal ions reduce the frontier orbital energies and introduces aromaticity. We consider a series of such complexes [$\eta$$^4$(Al$_4$Li$_4$)-Fe(CO)$_3$, $\eta$$^2$$\sigma$$^2$(Al$_4$Li$_4$)-Ni and (Al$_{4}$Li$_{4}$)$_{2}$Ni] 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.