High-spin stability of urea dication

High-spin stability of urea dication is analyzed as a trimethylenemethane analogue. MCSCF calculations revealed that the ground-state 3B2 lies below any other singlet state. The lowest singlet state 1B1 with a π–n configuration lies 9.74 kcal/mol above the 3B2 state, and a closed-shell singlet 1A1 lies far above the 3B2 state. The high-spin stability is due to pseudo non-bonding molecular orbitals and one-centered exchange integrals on cationic nitrogens. Band structure of polyuret is also presented as a design for novel ferromagnetic polymers.