Magnetic Anisotropy and Field-induced Slow Relaxation of Magnetization in Tetracoordinate Co(II) Compound [Co(CH(3)-im)(2)Cl(2)]

Static and dynamic magnetic properties of the tetracoordinate Co(II) complex [Co(CH(3)-im)(2)Cl(2)], (1, CH(3)-im = N-methyl-imidazole), studied using thorough analyses of magnetometry, and High-Frequency and -Field EPR (HFEPR) measurements, are reported. The study was supported by ab initio complete active space self-consistent field (CASSCF) calculations. It has been revealed that 1 possesses a large magnetic anisotropy with a large rhombicity (magnetometry: D = −13.5 cm(−1), E/D = 0.33; HFEPR: D = −14.5(1) cm(−1), E/D = 0.16(1)). These experimental results agree well with the theoretical calculations (D = −11.2 cm(−1), E/D = 0.18). Furthermore, it has been revealed that 1 behaves as a field-induced single-ion magnet with a relatively large spin-reversal barrier (U(eff) = 33.5 K). The influence of the Cl–Co–Cl angle on magnetic anisotropy parameters was evaluated using the CASSCF calculations.