Efficient synthesis and magnetic properties of triphenylamine bearing three nitronylnitroxide radicals

Improved synthesis and reinvestigation of the magnetic properties of triphenylamine bearing three nitronylnitroxide radicals (1) were carried out. Single crystal X-ray crystallographic analysis of 1 established that its molecular shape had a C3-symmetry. Our newly prepared 1 showed different physical properties from those of reported. SQUID measurements of 1 showed that each of the three spins of 1 behaved independently at room temperature. In contrast, the three spins coupled antiferromagnetically at lower temperature as low as ca. 1.8 K. These spin behaviors can be explained by a regular triangular antiferromagnetic model (J/kB = −3.3 K) and interpreted as a spin frustration system.

► We synthesized a triradical and reinvestigated its magnetic properties.
► The triradical has a C3-symmetrical molecular shape.
► The triradical showed different physical properties from those of reported.
► Tree spins on the triradical interact antiferromagnetically each other.
► The magnetic behavior was interpreted as a spin frustration system.