Non-traditional thermal behavior of Co(II) coordination networks showing slow magnetic relaxation

Author(s):  
Anna Switlicka ◽  
Barbara Machura ◽  
Alina Bieńko ◽  
Dariusz Bieńko ◽  
Cyril Rajnák ◽  
...  

Three new coordination polymers, one-dimensional ones [Co(5,6-(Me)2–bzim)2(dca)2] (1), [Co(5-Mebzim)2(dca)2]n (2) and two-dimensional polymer [Co(2-Mebzim)(dca)2]n (3), show DC magnetic data consistent with the S = 3/2 spin system with large zero-field...

2021 ◽  
Vol 7 (6) ◽  
pp. 76
Author(s):  
Cyril Rajnák ◽  
Ján Titiš ◽  
Roman Boča

A series of mononuclear Co(II) complexes showing slow magnetic relaxation is assessed from the point of view of relaxation mechanisms. In certain cases, the reciprocating thermal behavior is detected: On cooling, the slow relaxation time is prolonged until a certain limit and then, unexpectedly, is accelerated. The low-temperature magnetic data can be successfully fitted by assuming Raman and/or phonon bottleneck mechanisms of the slow magnetic relaxation for the high-frequency relaxation channel. An additional term with the negative temperature exponent is capable of reproducing the whole experimental dataset.


2020 ◽  
Vol 6 (4) ◽  
pp. 48
Author(s):  
Lu Xi ◽  
Jing Han ◽  
Xiaohui Huang ◽  
Licun Li

Employing a new nitronyl nitroxide biradical NITPhPzbis(NITPhPzbis = 5-(1-pyrazolyl)-1,3-bis(1’-oxyl-3’-oxido-4’,4’,5’,5’-tetramethyl-4,5-hydro-1H-imidazol-2-yl)benzene), a series of 2p-4f complexes [Ln2(hfac)6(H2O)(NITPhPzbis)] (LnIII = Gd1, Tb2, Dy3; hfac = hexafluoroacetylacetonate) were successfully synthesized. In complexes 1–3, the designed biradical NITPhPzbis coordinates with two LnIII ions in chelating and bridging modes to form a four-spin binuclear structure. Direct-current magnetic study of Gd analogue indicates that ferromagnetic exchange exists between the Gd ion and the radical while antiferromagnetic coupling dominates between two mono-radicals. Dynamic magnetic data show that the χ” signals of complex 3 exhibit frequency dependence under zero field, demonstrating slow magnetic relaxation behavior in complex 3. And the estimated values of Ueff and τ0 are about 8.4 K and 9.1 × 10−8 s, respectively.


2019 ◽  
Vol 48 (41) ◽  
pp. 15529-15536 ◽  
Author(s):  
Deyun Ma ◽  
Guo Peng ◽  
Ying-Ying Zhang ◽  
Bo Li

Two two-dimensional and three-dimensional Co(ii) coordination polymers with slow magnetic relaxation are reported, which enlarge the family of high-dimensional coordination polymers exhibiting single ion magnet behavior.


2015 ◽  
Vol 44 (48) ◽  
pp. 20834-20838 ◽  
Author(s):  
Xing-Cai Huang ◽  
Ming Zhang ◽  
Dayu Wu ◽  
Dong Shao ◽  
Xin-Hua Zhao ◽  
...  

Two one-dimensional coordination polymers with pentagonal bipyramidal DyIII centres show slow magnetic relaxation featuring single molecule magnet behavior.


CrystEngComm ◽  
2019 ◽  
Vol 21 (34) ◽  
pp. 5145-5151 ◽  
Author(s):  
Jiao-Jiao Kong ◽  
Jia-Chen Zhang ◽  
Yu-Xuan Jiang ◽  
Jin-Xia Tao ◽  
Wen-Yan Wang ◽  
...  

Two-dimensional heterometallic CuIILnIII (Ln = Gd, Tb and Dy) coordination polymers bridged by dicyanamides showed slow magnetic relaxation behaviour and a magnetic hysteresis loop at 1.8 K was observed for the CuTb compound.


2019 ◽  
Vol 5 (3) ◽  
pp. 40 ◽  
Author(s):  
Sara Moreno-Da Silva ◽  
Patricia Delgado-Martínez ◽  
Miguel Cortijo ◽  
Rodrigo González-Prieto ◽  
José Luis Priego ◽  
...  

We report herein on three zigzag one-dimensional coordination polymers of {[Ru2(μ-NHOCR)4](μ-SCN)}n (R = o-Me-C6H4 (2), m-Me-C6H4 (3), p-Me-C6H4 (4)) formula. These new compounds have been obtained by reaction of the corresponding [Ru2(μ-NHOR)4(THF)2](BF4) complex with (NBu4)(SCN) under different synthetic conditions. The crystal structure of [Ru2(μ-NHOCC6H4-o-Me)4(THF)2](BF4) (1), 2 and 3 are presented. A cis-(2,2) arrangement of the amidate ligands of the [Ru2(μ-NHOCR)4]+ units is observed in all cases. Interestingly, the structures of 2 and 3 show linkage isomerism in alternated tetraamidatodiruthenium units whose axial positions are occupied by the same type of donor atom of the SCN ligands. This results in zigzag chains with a Ru-S-C angle of 98.97° and Ru-N-C angle of 169.36° in the case of 2 and 97.99° and 159.26°, respectively, in the case of 3. The magnetic data obtained for 2–4 are indicative of a σ2π4δ2(π*δ*)3 ground state (S = 3/2) and a large zero-field splitting (ZFS) in all cases (D = 54.57, 62.72 and 43.00 cm−1 for 2–4, respectively). Similar small antiferromagnetic interactions between diruthenium units (zJ = −0.93, −0.79 and −1.11 cm−1 for 2–4, respectively) are estimated for all the polymers, suggesting an analogous zigzag arrangement of the chains for 4.


Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 697
Author(s):  
Nives Matijaković Mlinarić ◽  
Nikolina Penić ◽  
Boris-Marko Kukovec ◽  
Marijana Đaković

Two cadmium(II) coordination polymers, with thiocyanate and pyridine-based ligands e.g., 3-acetamidopyridine (3-Acpy) and niazid (nicotinic acid hydrazide, nia), namely one-dimensional {[Cd(SCN)2(3-Acpy)]}n (1) and two-dimensional {[Cd(SCN)2(nia)]}n (2), are prepared in the mixture of water and ethanol. The adjacent cadmium(II) ions in 1 are bridged by two N,S-thiocyanate ions and an N,O-bridging 3-Acpy molecule, forming infinite one-dimensional polymeric chains, which are assembled by the intermolecular N–H∙∙∙S hydrogen bonds in one direction and by the intermolecular S∙∙∙S chalcogen bonds in another direction. Within the coordination network of 2, the adjacent cadmium(II) ions are bridged by N,S-thiocyanate ions in one direction and by N,O,N’-chelating and bridging nia molecules in another direction. The coordination networks of 2 are assembled by the intermolecular N–H∙∙∙S and N–H∙∙∙N hydrogen bonds and S∙∙∙S chalcogen bonds. Being the only supramolecular interactions responsible for assembling the polymer chains of 1 in the particular direction, the chalcogen S∙∙∙S bonds are more significant in the structure of 1, whilst the chalcogen S∙∙∙S bonds which act in cooperation with the N–H∙∙∙S and N–H∙∙∙N hydrogen bonds are of less significance in the structure of 2.


2021 ◽  
Vol 7 (11) ◽  
pp. 150
Author(s):  
Carlo Andrea Mattei ◽  
Bertrand Lefeuvre ◽  
Vincent Dorcet ◽  
Gilles Argouarch ◽  
Olivier Cador ◽  
...  

The coordination reaction of the [Dy(hfac)3(H2O)2] units (hfac− = 1,1,1,5,5,5-hexafluoroacetylacetonate) with the [8′-(Diphenoxylphosphinyl)[1,1′-binaphthalen]-8-yl]diphenoxylphosphine oxide ligand (L) followed by a crystallisation in a 1:3 CH2Cl2:n-hexane solvent mixture led to the isolation of a new polymorph of formula [(Dy(hfac)3((S)-L))3]n (1). The X-ray structure on single crystal of 1 revealed the formation of a mono-dimensional coordination polymer with three crystallographically independent DyIII centres, which crystallised in the polar chiral P21 space group. Ac magnetic measurements highlighted single-molecule magnet behaviour under both zero and 1000 Oe applied magnetic field with magnetic relaxation through quantum tunneling of the magnetisation (QTM, zero field only) and Raman processes. Despite the three crystallographically independent DyIII centres adopting a distorted D4d coordination environment, a single slow magnetic relaxation contribution was observed at a slower rate than its previously studied [(Dy(hfac)3((S)-L))]n (2) polymorph.


2021 ◽  
Author(s):  
Júlia Mayans ◽  
Albert Escuer

A possible relation between the value of the axial Zero Field Splitting and the occurrence of field-induced slow magnetic relaxation has been established for a new gadolinium(iii) compound.


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