A series of diradical π-dimers 2 with interesting pancake-shaped 2e/24c π–π bonding character were designed and investigated based on the famous phenalenyl (PLY) π-dimer with 2e/12c π–π bonding character. The position of stronger interaction between two layers of radicals was found by the Wiberg bond index (WBI) maximum component. Further, the different contributions of the interaction energy were analyzed quantitatively by energy decomposition analysis (EDA). Among these new diradical π-dimers, 2₁₈₀ has the smallest layer distance and the largest interaction between two layers of radicals. The unusual PLY analogues can provide new insights into the unique features of two-electron/multicenter (2e/mc) π–π bonding.