Two cobalt complexes containing different nitronyl nitroxide radicals: Structure and magnetic properties

Two New Cobalt(II) Heterotrispin Dimers Bridged by Functional Nitronyl Nitroxides: Structure and Magnetic Properties

“…For complex 2, at a magnetic field of 70 kOe, the magnetization reaches a maximum of 1.34 Nβ, lower than the being saturated (S=1, g=2.18). This suggests the stronger antiferromagnetic interactions between the Co(II) ion and NITR ligand, which are consistent with the literature results for the Co-NIT systems[33][34][35][36][37].…”

“…As illustrated in Figures 5 and 6, the temperature dependence of the magnetic susceptibility of complexes 1 and 2 in the temperature range T > 50 K region can be well fitted depending on equations 1 and 2, leading to J= -292.65 cm −1 ，D= -22.40 cm −1 ， zJ=0, g=2.24, R=1.81×10 -6 for complex 1， J= −102.73 cm −1 ， D= -34.18 cm −1 ， zJ=0, g =2.18, R=2.2×10 -7 for complex 2. The results show the antiferromagnetic interaction between Co(II) ions and nitronyl nitroxides via Co(II)─O coordination bonding is very strong, which is agreement with those lectures [25,27,[30][31][32][33][34][35]. For complexes 1 and 2, the magnetization versus field curve obtained at 2 K are depicted in Based on the structures of complexes 1 and 2, the results illustrated that facts: because the octahedral Co(II) ion has a d electron configuration of (t2g) 5 -(e g) 2 in high spin state, orbital overlaps between the magnetic orbitals of Co dπ (t2g) and NITR π* should be appreciable, giving rise to antiferromagnetic coupling [38][39][40].…”

SMM Behavior Tuned by an Exchange Coupling LEGO Approach for Chimeric Compounds: First 2p–3d–4f Heterotrispin Complexes with Different Metal Ions Bridged by One Aminoxyl Group

“…For example, Jian et al reported a moderate value of −15.4 cm –1 for the Co II –Rad interaction within an azido-bridged binuclear complex . Very weak antiferromagnetic interactions have been observed by Zhang et al in two cobalt­(II)–nitronyl–nitroxide complexes …”

“…27 Very weak antiferromagnetic interactions have been observed by Zhang et al in two cobalt(II)−nitronyl−nitroxide complexes. 28 Ac magnetic susceptibility measurements were performed for [Co II Dy III (L 4 H)(hfac) 5 ] 5a, under zero dc magnetic field, showing tunneling of the magnetization for the lowest temperatures (Figure S5). Therefore, the ac measurements were also performed under a static dc field (1500 Oe), revealing the occurrence of slow relaxation of the magnetization below 28 K for the available frequencies, which is quite high for such systems (Figure 7).…”