The crystal structure and magnetic properties of an organic verdazyl biradical

The crystal structure and magnetic properties of metaphenylenebisverdazyl biradical (m-Ph-V₂) are presented. The temperature dependence of the product of the magnetic susceptibility and temperature, which is proportional to the square of the effective magnetic moment, shows a round maximum at about 40 K and a stationary behaviour at half the value of the room temperature in the temperature range of 4-7 K In the crystal structure, the dimeric structure of molecules is noticeable and the susceptibility data were analysed by the four-spin cluster model with an S = 1/2. The intrarmolecular ferromagnetic interaction was estimated to J₁/k_B = -40 K.