Cluster-assembled compounds comprising an all-metal subunit Li3Al4−

Abstract

The recent, experimentally-discovered, all-metal antiaromatic Li₃Al₄⁻ has attracted great interest and extensive investigations due to its unique chemical bonds and exotic properties. Although a very recent theoretical study demonstrated that the all-metal species Li₃Al₄⁻ can be effectively stabilized by complexation with 3d transition metals, unfortunately such stabilization is at the expense of losing antiaromaticity (rectangular Al₄) to become aromatic (square Al₄). Here, we predict theoretically a series of cluster-assembled compounds [DM(Li₃Al₄)]^q− (D = Li₃Al₄⁻, Cp⁻; M = Li, Na, K, Be, Mg, Ca). The assembled species are ground states containing the all-metal antiaromatic Li₃Al₄⁻ subunits. Many fusion isomers are energetically lower than the homo-decked cluster-assembled compounds, thus, the homo-decked assembly species [M(Li₃Al₄)₂]^q− are less likely due to their thermodynamic instability. In addition, the well-retained all-metal antiaromaticity is mainly ascribed to the ionic electrostatic interactions and the protections of rigid organic aromatic Cp-deck avoiding the fusion of Li₃Al₄⁻. Our results represent the first example that the all-metal antiaromaticity is well retained in assembled compounds as that in the free Li₃Al₄⁻cluster. Sufficiently large interaction energies make the realization of all-metal antiaromatic Li₃Al₄⁻-incorporated compounds very promising.