The previous examples of four atom systems displaying two layers of aromaticity illustrated how 4 (B ₄ ), 8 (C ₄ ) and 12 (N ₄ ) valence electrons were partitioned into 4n+2 manifolds (respectively 2+2, 6+2 and 6+6). The triplet state molecule B ₂ C ₂ with 6 electrons partitioned into 2π and 4σ electrons, with the latter following Baird’s aromaticity