High-spin state instability in nitroxide triradical coupled through m-phenylene

The electronic structure of 2-methoxy-1,3,5-benzenetriyltris (N-hydronitroxide) (MBTN) is discussed with the ab initio molecular orbital method at the second-order M0ller-Plesset perturbation level of theory. The result explains why high-spin states are unstable in some hindered nitroxide di-and triradicals coupled through m-phenylene.