Structures and Aromaticity of Planar XY2Z （X=Li,K,Y=P,As and Z=C,Si,Ge） Clusters

Clusters XY2Z species are theoretically investigated with density functional theory(DFT) method.The results show that for LiP2C,LiAs2Ge and KAs2C species,the C2v isomer is the most stable planar structure,while for other species the Cs isomer is the most stable planar structure at the B3LYP/6-311+G level.Wiberg Bond Index(WBI) and Nucleus-Independent Chemical Shift(NICS) values indicate the existence of delocalization in stable planar structures.A detailed Molecular Orbital(MO) analysis further reveals that planar isomers of these species have strong aromatic character,which strengthens the structural stability and makes them closely connect with the concept of aromaticity.