Magnetic property of 1:2 mixture of Co(p-tolsal)₂; p-tolsal = N-p-tolylsalicylideniminato, and cyclic pentacarbene-pyridine with S = 10/2 in dilute frozen solution

A cyclic pentadiazo-pyridine ligand, cD5py, was prepared and its photoproduct, cC5py, in a frozen solution was confirmed to be a high-spin polycarbene with S = 10/2. The magnetic property of the 1:2 mixture of Co(p-tolsal)₂; p-tolsal = N-p-tolylsalicylideniminato, and cD5py in a dilute frozen solution after irradiation was investigated by SQUID magneto/susceptometry. In the ac magnetic susceptibility measurements, the in-phase and out-of-phase components (χ′ and χ″, respectively) with frequency dependence were observed, indicating that the 1:2 complex, Co(p-tolsal)₂-(cC5py)₂, had slow magnetic relaxation characteristic of the single-molecule magnet (SMM). From the χ″ versus T plots with various frequencies, the values of activation barrier, U_eff, for the reverse of the magnetism was estimated to be 72 K. In the dc magnetic susceptibility measurements, the magnetic hysteresis loops were observed below 3 K. The value of the coercive force, H_c, depends on the temperature and increases on cooling. The hysteresis loop with H_c = 7.1 kOe was observed at 1.9 K.