For a perpendicular configuration (φ = 90º), J = 0.8 meV. One of the simplest SCU for this system is the -CH3 group (denoted as TRI(N)CH3-TRI(N)CH3), which fixes the dihedral angle to φ = 80º, and yields FM interaction of J = 0.4 meV (Table and Figure ). These results demonstrate the first example of triangulene dimers with FM coupling and hold great potential to regulate the magnetic interactions in metal-free spin dimers and subsequent oligomers and polymers. This tunable magnetic interaction in TRI(N) dimer highlights the unconventional magnetism defying