Geometrical structure, aromaticity and other properties of Al2P22-, [M(Al 2 P 2 )] − (M=Li, Na, K, Cu) and N(Al 2 P 2 ) (N=Be, Mg, Ca, Zn) species are theoretically investigated with density functional theory (DFT) methods. Calculation results show that for Al2P22- species, the planar structure, with D 2h symmetry at the 1 A g state, is the global minimum at the B3LYP/6-311+G ∗ level. Natural bond orbital (NBO) analysis indicates the existence of delocalization in the most stable Al2P22- species and its pyramidal complexes. Nucleus-independent chemical shift (NICS) and molecular orbital (MO) analysis further reveal that that pyramidal [M(Al 2 P 2 )] − and N(Al 2 P 2 ) species preserve the aromatic nature of the most stable Al2P22- unit.