Compounds having two p-phenoxyl radicals bridged by a 1, 2-diphenylenedisilanylene unit in m, p-and p, p-fashions were synthesized and the intramolecular spin–spin interaction was examined by Curie plots of ESR signal intensities due to the ΔMS=±2 transition at low temperature. It was found that bridging two phenoxyl radicals at meta and para positions of the bridge led to triplet ground state or degeneracy of triplet/singlet states. In contrast, two ...