We have identified several functionalized pentalenes, s-indacenes and indeno[1,2,3-e f ]heptalenes with inverted singlet-triplet gaps. Furthermore, we find many molecules with higher-lying Hund's rule violations where the inversion is between S 1 and a higher triplet state of the same electron configuration, thus leaving the S 1 -T 1 gap positive. This reveals there is a broad structural diversity in the non-alternant hydrocarbon class of inverted gap emitters, similar to that seen in the azaphenalene class.