High-spin tetranuclear iron(III) grids: Synthesis, crystal structure and magnetic properties

Polyhedron ◽  
2013 ◽  
Vol 52 ◽  
pp. 970-975 ◽  
Author(s):  
Yi-Tong Wang ◽  
Ai-Li Cui ◽  
De-Zhong Shen ◽  
Hui-Zhong Kou
2017 ◽  
Vol 46 (9) ◽  
pp. 2957-2965 ◽  
Author(s):  
Olga V. Yakubovich ◽  
Larisa V. Shvanskaya ◽  
Galina V. Kiriukhina ◽  
Anatoly S. Volkov ◽  
Olga V. Dimitrova ◽  
...  

The title borophosphate is characterized by a rare combination of the magnetic high-spin Mn2+ ions in both octahedral and tetrahedral coordinations. The crystal structure and magnetic properties are presented.


2021 ◽  
Vol 7 (7) ◽  
pp. 105
Author(s):  
Min Zeng ◽  
Xi Chen ◽  
Hui-Zhong Kou

Two carboxylate-bridged one-dimensional chain complexes, {[MnII(MeOH)2][FeIII(L)2]2}n (1) and {[MnII(DMF)2][MnIII(L)2]2·DMF}n (2) [H2L = ((2-carboxyphenyl)azo)-benzaldoxime], containing a low-spin [FeIII(L)2]− or [MnIII(L)2]− unit were synthesized. Magnetic measurements show that the adjacent high-spin MnII and low-spin MIII ions display weak antiferromagnetic coupling via the syn–anti carboxyl bridges, with J = −0.066(2) cm−1 for complex 1 and J = −0.274(2) cm−1 for complex 2.


Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 112 ◽  
Author(s):  
Maria Zentkova ◽  
Marian Mihalik

We present the review of pressure effect on the crystal structure and magnetic properties of Cr(CN)6-based Prussian blue analogues (PBs). The lattice volume of the fcc crystal structure space group Fm 3 ¯ m in the Mn-Cr-CN-PBs linearly decreases for p ≤ 1.7 GPa, the change of lattice size levels off at 3.2 GPa, and above 4.2 GPa an amorphous-like structure appears. The crystal structure recovers after removal of pressure as high as 4.5 GPa. The effect of pressure on magnetic properties follows the non-monotonous pressure dependence of the crystal lattice. The amorphous like structure is accompanied with reduction of the Curie temperature (TC) to zero and a corresponding collapse of the ferrimagnetic moment at 10 GPa. The cell volume of Ni-Cr-CN-PBs decreases linearly and is isotropic in the range of 0–3.1 GPa. The Raman spectra can indicate a weak linkage isomerisation induced by pressure. The Curie temperature in Mn2+-CrIII-PBs and Cr2+-CrIII-PBs with dominant antiferromagnetic super-exchange interaction increases with pressure in comparison with decrease of TC in Ni2+-CrIII-PBs and Co2+-CrIII-PBs ferromagnets. TC increases with increasing pressure for ferrimagnetic systems due to the strengthening of magnetic interaction because pressure, which enlarges the monoelectronic overlap integral S and energy gap ∆ between the mixed molecular orbitals. The reduction of bonding angles between magnetic ions connected by the CN group leads to a small decrease of magnetic coupling. Such a reduction can be expected on both compounds with ferromagnetic and ferrimagnetic ordering. In the second case this effect is masked by the increase of coupling caused by the enlarged overlap between magnetic orbitals. In the case of mixed ferro–ferromagnetic systems, pressure affects μ(T) by a different method in Mn2+–N≡C–CrIII subsystem and CrIII–C≡N–Ni2+ subsystem, and as a consequence Tcomp decreases when the pressure is applied. The pressure changes magnetization processes in both systems, but we expect that spontaneous magnetization is not affected in Mn2+-CrIII-PBs, Ni2+-CrIII-PBs, and Co2+-CrIII-PBs. Pressure-induced magnetic hardening is attributed to a change in magneto-crystalline anisotropy induced by pressure. The applied pressure reduces saturated magnetization of Cr2+-CrIII-PBs. The applied pressure p = 0.84 GPa induces high spin–low spin transition of cca 4.5% of high spin Cr2+. The pressure effect on magnetic properties of PBs nano powders and core–shell heterostructures follows tendencies known from bulk parent PBs.


2006 ◽  
Vol 791 (1-3) ◽  
pp. 98-105 ◽  
Author(s):  
Bogumiła Żurowska ◽  
Jerzy Mroziński ◽  
Zbigniew Ciunik ◽  
Justyn Ochocki

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 366
Author(s):  
Bohuslav Drahoš ◽  
Peter Antal ◽  
Ivan Šalitroš ◽  
Radovan Herchel

In order to prepare an Fe(II) spin crossover (SCO) complex that could be consequently modified to a bimetallic coordination compound that possesses another magnetic property of interest, a specially designed ligand L-NH2 (1-(4-aminobenzyl)-4,11-bis(pyridine-2-ylmethyl)- 1,4,8,11-tetraazacyclotetradecane) was prepared. This ligand consists of a macrocyclic cyclam part containing two 2-pyridylmethyl pendant arms (expecting SCO upon Fe(II) complexation) and one p-aminobenzyl pendant arm with an NH2 group. The presence of this group enables the consequent transformation to various functional groups for the selective complexation of other transition metals or lanthanides (providing the second property of interest). Furthermore, the performed theoretical calculations (TPSSh/def2-TZVP) predicted SCO behavior for the Fe(II) complex of L-NH2. Thus, Fe(II) complexes [Fe(L-NH2)](ClO4)2 (1) and [Fe(L-NH2)]Cl2·6H2O (2) were synthesized and thoroughly characterized. Based on the crystal structure of an isostructural analogous Ni(II) complex [Ni(L-NH2)]Cl2·6H2O (3), the coordination number six was confirmed with an octahedral coordination sphere and a cis-arrangement of the pyridine pendant arms. The measured magnetic data confirmed the high-spin behavior of both compounds with large magnetic anisotropy (D = 17.8 for 1 and 20.9 cm−1 for 2 complemented in both cases also with large rhombicity), though unfortunately without any indication of the SCO behavior with decreasing temperature. The lack of SCO can be ascribed to the crystal packing and/or the non-covalent intermolecular interactions stabilizing the high-spin state in the solid state.


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