Tuning the position of unpaired electrons and doublet-quartet gap of the 1,3,5-trimethylenebenzene triradical by nitrogen, phosphorus and arsenic substitution

► The role of the nitrogen, phosphorus and arsenic substitution of the ring C-H groups of 1,3,5-trimethylenebenzene triradical was systematically studied using high level multi-reference and density functional methods. High-spin-low-spin gaps, electronic structure and chemical bonding were investigated. ► It was showed that the high-spin-low-spin gap can be tuned using chemical modification of the molecule. ► Also the spatial distribution of the unpaired electrons can be tuned by chemical modification. These provide a potential application in the design of molecular magnets. ► The results are interpreted with the aid of the Wiberg indices and the electron localization function.