Phonon-induced relaxation mechanisms are changed by a chelating effect in a Co^II single-ion magnet

Abstract

Compound 1 contains a rigid chelating ligand and compounds 2 and 3 contain monodentate dangling pyridine ligands. The rigid chelating ligand can efficiently change the phonon induced magnetization relaxation processes at low temperatures.

Cobalt(II) Single-Ion Magnet Coordinated by Double Deprotonation of 2,2′-Bipyridine-6,6′-diol Ligands

“…Their out-of-phase signals appear above 20 K in zero DC magnetic field, making them the strongest Co­(II) SIMs in all cases. The last four compounds involve amide anions combined with pyridine or imine moieties. ,,, Their D values typically fall between −50 and −60 cm –1 , with a case of D = −94 cm –1 also reported. Regardless of the D value, their out-of-phase signals mostly appear around 10 K. From the analysis in Scheme , it can be inferred that among pseudotetrahedral configurations, SIMs coordinating four sulfonamide or amide anions exhibit the highest out-of-phase temperatures, followed by compounds with amide anions combined with pyridine or imine moieties.…”

“…In 2022, our laboratory combined chelating sulfonamide ligands with monodentate pyridine and chelating 2,9-diphenyl-phenanthroline ligands. The results showed that only the rigid and chelating ligand 2,9-diphenyl-phenanthroline exhibited out-of-phase signals up to 12 K without an applied DC magnetic field . While pyridine-like ligands typically act as π donors in the angular overlap model (AOM), these two cases suggest that replacing two of the four amido anion ligands with pyridines can decrease the temperatures at which out-of-phase signals occur.…”

“…The results showed that only the rigid and chelating ligand 2,9-diphenyl-phenanthroline exhibited out-of-phase signals up to 12 K without an applied DC magnetic field. 16 While pyridine-like ligands typically act as π donors in the angular overlap model (AOM), 17 these two cases suggest that replacing two of the four amido anion ligands with pyridines can decrease the temperatures at which out-of-phase signals occur. In 2020, we employed only 2,9-diphenyl-phenanthroline as the ligand.…”

Solvent effect on the structures of three manganese complexes based on azotetrazole-3-hydroxy-2-naphthoic acid: synthesis, structures, and magnetic and fluorescent properties

“…Coordination complexes with novel structures have drawn the attention of chemists in recent years due to their intriguing topologies and potential applications in the fields of catalysis, sensing, gas sorption and so on. [1][2][3][4][5][6][7][8][9][10][11] To our knowledge, many factors, such as the coordinated metal ions, [12][13][14] organic ligands, [15][16][17][18][19][20] solvent systems, [21][22][23][24] reaction temperature, [25][26][27][28] and pH values, 29,30 have been well-recognized to influence the structure of these complexes. Among the aforementioned factors, the solvent is the most widely used factor to regulate the structure of coordination complexes, and it further affects the overall framework, network dimensionality and even the properties.…”

Slow magnetic relaxation and spin crossover behavior in two mixed-valence Co(ii)/Co(iii) complexes

“…30 Many issues including the control of spin, magnetic anisotropy and the relaxation mechanisms remain to be solved. 31–33 Searching for well-defined correlations between different structural factors and the magnetic anisotropy in transition metal complexes remains a great challenge and much more work is required to extend our knowledge for the rational design of new magnetic materials. 33–40…”