Theoretical Investigation on Triagonal Symmetry Copper Trimers: Magneto-Structural Correlation and Spin Frustration

Abstract

The mechanisms of the magnetic coupling interactions for two trigonal-bipyramid trinuclear Cu(II) complexes Cu3(mu3-X)2(mu-pz)3X3 (X = Cl and Br, respectively) and three trigonal trinuclear Cu(II) complexes Cu3(mu3-X)(mu-pz)3Cl3 (X = Cl, Br, and O) are investigated by the calculations based on density functional theory combined with broken-symmetry approach (DFT-BS). The research on the magneto-structural correlation reveals that the magnetic coupling interaction is sensitive to the Cu-(mu3-X)-Cu angle. With the Cu-(mu3-X)-Cu angle changing from 76 to 120 degrees, the magnetic coupling interaction is switched from ferromagnetic to antiferromagnetic. According to the analysis of the molecular orbitals and the variation of the spin-state energies versus the ratio of the magnetic coupling constants, it is found that there exists spin frustration phenomenon in these complexes.

Interactions between H-bonded [CuII3(μ3-OH)] triangles; a combined magnetic susceptibility and EPR study

“…This parameter depends on the nature of the ground state, which, in the isosceles configuration in the absence of antisymmetric exchange, can be expressed as . In this notation, spins S 2 and S 3 couple to yield an intermediate spin S 23 , which subsequently couples with S 1 to yield the total spin S. The two S = 1/2 states Qualitatively, the two cases can be understood as follows: In case I, the antiferromagnetic coupling in the pairs [Cu(1), Cu(2)] and [Cu(1), Cu(3)] forces Cu (2) and Cu(3) to align antiparallel with Cu (1). In this case Cu (2) and Cu(3) align parallel to each other, yielding S 23 = 1.…”

“…The simulations shown in Fig. 5 for the X-band dual mode spectra were obtained for: g ab|| = 2.25(1), g ab⊥ =1.66 (1) and r ab = 4.5(2) Å. For the Q-band (Fig.…”

“…Magnetic interactions among metal centers in a trinuclear, triangular arrangement comprising half-integer spin ions have been of interest for a long time as their study probes fundamental questions of magnetic exchange, such as the magnitude of isotropic exchange, spin frustration and the role of antisymmetric exchange. [1][2][3][4][5][6][7][8] In addition to classical throughbond exchange, supramolecular interactions between triangular units have also been of interest in the construction of molecule-based quantum gates for quantum information processing. 9 Trinuclear copper centers, such as those encountered in the active centers of several metalloproteins -e.g., small laccase, which assists in the reduction of O 2 -are of additional interest, because of their critical role in biological processes.…”

Are trinuclear superhalogens promising candidates for building blocks of novel magnetic materials? A theoretical prospect from combined broken-symmetry density functional theory and ab initio study

“…With the help of DFT-BS calculation, the Kambe model has been successfully applied in trinuclear complexes, 37,38,43,52,96,98 where the accuracy of DFT-BS study has been proven by the comparison with high level multireference theory 52,53 and with accurate experimental results. 37 Based on the calculated ECCs in Sec.…”

Trinucleating Copper: Synthesis and Magnetostructural Characterization of Complexes Supported by a Hexapyridyl 1,3,5‐Triarylbenzene Ligand

“…Similar trends extended to more complex systems have been complicated by the presence of multiple exchange pathways. Nevertheless, a non‐linear trend has been reported for the Cu‐(μ 3 ‐X)‐Cu angle for μ 3 ‐bridged trimers 15b,c. The present compounds allow for a systematic magnetostructural study.…”