Ligand-field regulated superalkali behavior of the aluminum-based clusters with distinct shell occupancy

Protecting clusters from coalescing by ligands has been universally adopted in the chemical synthesis of atomically precise clusters.Apart from the stabilization role,the effect of ligands on the electronic properties of cluster cores in constructing superatoms,however,has not been well understood.In this letter,a comprehensive theoretical study about the effect of an organic ligand,methylated N-heterocyclic carbene(C_(5)N_(2)H_(8)),on the geometrical and electronic properties of the aluminum-based clusters XAl_(12)(X=Al,C and P)featuring different valence electron shells was conducted by utilizing the density functional theory(DFT)calculations.It was observed that the ligand can dramatically alter the electronic properties of these aluminum-based clusters while maintaining their structural stability.More intriguingly,different from classical superatom design strategies,the proposed ligation strategy was evidenced to possess the capability of remarkably reducing the ionization potentials(IP)of these clusters forming the ligated superalkalis,which is regardless of their shell occupancy.The charge transfer complex formed during the ligation process,which regulates the electronic spectrum through the electrostatic Coulomb potential,was suggested to be responsible for such an IP drop.The ligation strategy highlighted here may provide promising opportunities in realizing the superatom synthesis in the liquid phase.