The σ-aromatic clusters [Zn₃]⁺ and [Zn₂Cu]: embryonic brass.

The triangular clusters [Zn3Cp*3](+) and [Zn2CuCp*3] were obtained by addition of the in situ generated, electrophilic, and isolobal species [ZnCp*](+) and [CuCp*] to Carmona's compound, [Cp*Zn-ZnCp*], without splitting the ZnZn bond. The choice of non-coordinating fluoroaromatic solvents was crucial. The bonding situations of the all-hydrocarbon-ligand-protected clusters were investigated by quantum chemical calculations revealing a high degree of σ-aromaticity similar to the triatomic hydrogen ion [H3](+). The new species serve as molecular building units of Cu(n)Zn(m) nanobrass clusters as indicated by LIFDI mass spectrometry.