The ground and low-lying excited states of the 5-dehydro-meta-xylylene and 2-dehydro-meta-xylylene triradicals, as well as their derivatives are characterized by the equation-of-motion spin-flip coupled-cluster method with single and double substitutions. The effect of substituents in the C2, C4, and C6 positions on electronic states ordering is investigated. In the 5-dehydro-meta-xylylene triradical, which has the 1(2)B(2) ground state, charged substituents at C2 stabilize the closed-shell 1(2)A(1) state, whereas the NO substituent lowers the 1(2)A(2) and 1(2)B(1) states. In the 2-dehydro-meta-xylylene tritadical with the 1(4)B(2) ground state charged substituents also significantly stabilize the 1(2)A(1) state and 1(2)B(1) state. The observed effects are explained by the nodal structure of the pi orbitals and charge localization in the sigma radical center. (c) 2006 Elsevier B.V. All rights reserved.