A Highly Anisotropic Cobalt(II)-Based Single-Chain Magnet: Exploration of Spin Canting in an Antiferromagnetic Array

Abstract

In this article we report for the first time experimental details concerning the synthesis and full characterization (including the single-crystal X-ray structure) of the spin-canted zigzag-chain compound [Co(H2L)(H2O)]infinity [L = 4-Me-C6H4-CH2N(CPO3H2)2], which contains antiferromagnetically coupled, highly magnetically anisotropic Co(II) ions with unquenched orbital angular momenta, and we also propose a new model to explain the single-chain magnet behavior of this compound. The model takes into account (1) the tetragonal crystal field and the spin-orbit interaction acting on each Co(II) ion, (2) the antiferromagnetic Heisenberg exchange between neighboring Co(II) ions, and (3) the tilting of the tetragonal axes of the neighboring Co units in the zigzag structure. We show that the tilting of the anisotropy axes gives rise to spin canting and consequently to a nonvanishing magnetization for the compound. In the case of a strong tetragonal field that stabilizes the orbital doublet of Co(II), the effective pseudo-spin-1/2 Hamiltonian describing the interaction between the Co ions in their ground Kramers doublet states is shown to be of the Ising type. An analytical expression for the static magnetic susceptibility of the infinite spin-canted chain is obtained. The model provides an excellent fit to the experimental data on both the static and dynamic magnetic properties of the chain.

Constructing Single‐Chain Magnets by Supramolecular π–π Stacking and Spin Canting: A Case Study on Manganese(III) Corroles

“…Indeed, since the first example of SCMs, [Co(hfac) 2 (NITPhOMe)] (hfac = hexafluoroacetylacetonate; NITPhOMe = 4'-methoxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide radical) reported by Gatteschi and co-workers, [1] bridging ligands such as oximate, [2] CN À , [7][8][9][10][11][12][13][14][15] N 3 À , [16] organic radicals, [2,17] oxalate, [3,18] oxamato, [19][20][21] tetracyano-A C H T U N G T R E N N U N G quinodimethane, [22] and phosphate/phosphamato [23,24] were considered to play a crucial role in transmitting strong intrachain magnetic coupling interactions. Although tremendous progress in SCMs constructed by bridging ligands has been achieved in recent years, some fundamental issues concerning the relationship between the structures and magnetic properties of SCMs, such as recognizing the contribution of weak intrachain magnetic coupling interaction, exploring novel approaches to construct new type of SCMs, and so on, still remain.…”

Two New Three-Dimensional Pillared-Layer Co(II) and Cu(II) Frameworks Involving a [M2(EO-N3)2] Motif from a Semi-Flexible N-Donor Ligand, 5,5′-Bipyrimidin: Syntheses, Structures and Magnetic Properties

“…Elemental analysis calcd. (%) for C 8 (2) A solution of Cu(NO 3 ) 2 ·3H 2 O (33 mg, 0.13 mmol) in methanol (5 mL) was carefully layered on top a solution of bpym (10 mg, 0.06 mmol), and NaN 3 (17 mg, 0.26 mmol) in water (5 mL). It was then allowed to stand for two weeks at room temperature, whereupon block needle crystals of 2 were formed.…”

“…As shown in Figure 3c, the bpym ligands in 2 acts a twisted From a topology point of view of the complicated 3D framework of 2, each square pyramidal Cu(II) center connecting to three neighboring Cu(II) centers by one basal µ-pyrimidyl ring, one apical µ-pyrimidyl ring and a pair of basal EO-N 3 group can be regarded as a pyramidal three-connected node, while each twisted µ 4 -bpym ligand can be considered to be an elongated tetrahedral four-connected node. A TOPOS analysis [28] indicates that the net of 2 can be rationalized as a binodal (3,4)-connected tfi topology with the Schläfli symbol (6 2 .8 4 )(6 2 .8) 2 as illustrated in Figure 4.…”

“…The constructions of functional one-, two-and three-dimensional coordination polymeric materials (CPs) using paramagnetic metal ions are of great interest because of the potential applications in a variety of areas due to their intriguing network topologies [1][2][3][4][5][6][7][8], such as electronic properties, magnetic properties, host-guest chemical properties, ion exchanging behaviors, catalysis, nanotechnology, fluorescence properties, nonlinear optical properties, etc. The abilities for magnetic CPs to establish relationships for structure-property, such as magneto-structural correlations toward molecule-based magnets, are key issues to develop this rapidly growing field of chemistry [9][10][11][12].…”

“…Herein, we report on the synthesis and characterization of two new coordination polymers, [Co 2 (N 3 ) 4 (bpym) 2 ] n (1) and [Cu 2 (N 3 ) 4 (bpym) 2 ] n (2), prepared using bpym and azide as co-ligands. Both 1 and 2 are made up of 3D frameworks involving a double end-on (EO) azido bridged dinuclear motif, [M 2 (EO-N 3 ) 2 ], with pillared-layer architectures.…”