Strong Coupling and Slow Relaxation of the Magnetization for an Air-Stable [Co₄] Square with Both Tetrazine Radicals and Azido Bridges

Abstract

Introducing both tetrazine radical and azido bridges afforded two air-stable square complexes [MII 4(bpztz•–)4(N3)4] (MII = Zn2+, 1; Co2+, 2; bpztz = 3,6-bis­(3,5-dimethyl­pyrazolyl)-1,2,4,5-tetrazine), where the metal ions are cobridged by μ1,1-azido bridges and tetrazine radicals. Magnetic studies revealed strong antiferromagnetic metal–radical interaction with a coupling constant of −64.7 cm–1 in the 2J formalism in 2. Remarkably, 2 exhibits slow relaxation of magnetization with an effective barrier for spin reverse of 96 K at zero applied field.

Self-assembly of Ni(ii) metallacycles (a square and a triangle) supported by tetrazine radical bridges

“…S8 †). 15 For 2, the magnetization increases continuously and does not saturate at high fields (2.81 Nβ at 2 K and 7 T), further confirming the overall antiferromagnetic couplings in such a complex (Fig. S9 †).…”

“…In terms of the overall charge balance, all the four bpz*tz ligands are supposed to be in the bpz*tz •− radical form. This is further evidenced by the significant elongation of the intra-tetrazine N-N bond distance (N1-N2, 1.372(3) Å; N3-N4, 1.395(4) Å), in comparison with those reported in the neutral form (∼1.32 Å) 6,15. All the Ni(II) ions are almost arranged in a square planar manner, with adjacent Ni⋯Ni distances of 3.56 Å and vertex Ni-Ni-Ni angles of 92.90°.…”

Field-induced slow magnetic relaxation behaviours in binuclear cobalt(ii) metallocycles and exchange-coupled clusters

“…Single-molecule magnets (SMMs) are well-known for their slow magnetic relaxation behavior with a purely molecular origin, which makes them have a variety of potential applications in molecular spintronic devices, quantum computing, and data storage. [1][2][3] To date, SMM behavior has been observed in a myriad of molecules with various magnetic structures, such as molecular triangles, 4 squares, 5 wheels, 6 and metallo-supramolecular structures. 7,8 Recently, research focus has shifted largely from molecules with a large spin ground state to monometallic complexes, known as single-ion magnets (SIMs).…”

Coordination Polymers Driven by Carboxy Functionalized Picolinate Linkers: Hydrothermal Assembly, Structural Multiplicity, and Catalytic Features

“…Coordination polymers (abbreviated as CPs) have become an exceptionally popular class of crystalline metal–organic solids with a vast diversity of applications. − These encompass such areas as selective sorption, − sensing, − and luminescence, − bioactive, − and magnetic materials, − as well as catalysis. − A significant body of research is also dedicated to synthetic chemistry and crystal engineering, with a focus on preparing new compounds and widening a structural diversity of CPs, − as well as on establishing potential correlations between structures and types of ligands, ,, metal nodes, crystallization conditions, and other reaction parameters.…”