Sandwich-Like Complexes Based on “All-Metal” (Al₄²⁻) Aromatic Compounds

We report a new sandwich-like structure (Al4TiAl42-) based on the recently synthesized all-metal aromatic Al42- squares. This structure has two aromatic squares (-2 charged each) trapping a titanium +2 cation. These all-metal aromatic squares have been detected by various metallic counterions, with a global charge of -1. Thus, we have also characterized a similar sandwich-like structure interacting with one and two sodium atoms with global charges of -1 and 0. The properties of these compounds strongly support the idea that they may be formed by Al42- aromatic squares.