Herein, we report the construction of a neutral, radical-rich, cobalt valence tautomeric triangle, which consists of two types of radical groups including tetrazine-based bridges and semiquinone anions at high temperature and has traits of high intensity and density of sensing sites. The mechanism of the Valence Tautomerism process within the triangle has been illustrated as one electron transfer, preceding a two electrons transfer along with the phenomenon of spin flipping.