Achieving Stable Hypercarbon CB₆²⁻-Based Cluster-Assembled Complexes: A General Strategy

A general strategy for designing stable hypercarbon CB62−-based cluster-assembled compounds CpM(CB6)q− (M = Li, Na, K, Be, Mg, and Ca) is proposed. This approach takes advantage of (1) the extra stability of a rigid organic aromatic Cp− deck, (2) the electrostatic interactions, (3) charge transfer based on orbital interaction, and (4) the good electronic match between the CB62− and CpM fragments. The nature and origin of various sandwich-type interactions and the requirements and technologies of the sandwiching decks’ assembly and stabilization are generally classified and comprehensively revealed. The quite crucial to perform fusion stability investigation is performed by comprehensive thermodynamic stability calculations. The electrostatic and orbital interactions and charge transfer in our designed hypercarbon complexes CpM(CB6)q− are revealed by detailed NBO analysis, orbital characterization, and frontier molecular orbital theory. Detailed analysis and comparison of the intrinsic difference of cluster-assembled compounds between hypercarbon phC CB62− and pentaatomic ptC CAl42− are performed.