Organic Two-Step Spin-Transition-Like Behavior in a Linear <i>S</i> = 1 Array: 3′-Methylbiphenyl-3,5-diyl Bis(<i>tert</i>-butylnitroxide) and Related Compounds

The title compound showed a unique low-dimensional array with S = 1 molecules. The intermolecular antiferromagnetic coupling and intramolecular ferromagnetic coupling are simultaneously present, and accordingly, the S = 1/2 state appeared at 230−350 K between the diamagnetic phase and the paramagnetic S = 1 phase. The solid−solid phase transition occurred in a single-crystal-to-single-crystal manner. The corresponding 3′-methoxy derivative is also presented for comparison.