Two New Cobalt(II) Heterotrispin Dimers Bridged by Functional Nitronyl Nitroxides: Structure and Magnetic Properties

Ma, Jin-Ke; Chen, Jing; Zhang, You-Juan; Wang, Qing-Lun

doi:10.1166/sam.2023.4492

Cited by 1 publication

(2 citation statements)

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“…Selected bond distances, bond angles, and contacts are summarized in Table 1 and Tables S4-S7 (Supplementary Materials). In the [Co(hfac)2L F ]2 dimer, which crystallizes in the triclinic P-1 space group, the Co-ONO bond length is 2.032(2) Å, and the Co-N bond length is 2.150(2) Å, which are comparable to those observed in previously described cyclic cobalt-nitroxide cyclic dimers [51][52][53]. In the coordinated nitroxide group, the bond length is slightly greater The structure of [Mn(hfac) 2 L F ] 2 results from bridging bidentate ligand coordination via the nitroxide O atom and the N atom of the pyrazole ring.…”

Section: Synthesis and Structures Of Complexessupporting

confidence: 81%

“…In the [Co(hfac) 2 L F ] 2 dimer, which crystallizes in the triclinic P-1 space group, the Co-O NO bond length is 2.032(2) Å, and the Co-N bond length is 2.150(2) Å, which are comparable to those observed in previously described cyclic cobalt-nitroxide cyclic dimers [51][52][53]. In the coordinated nitroxide group, the bond length is slightly greater [1.308(2) Å] as compared with the noncoordinated one [1.266(3) Å].…”

Section: Synthesis and Structures Of Complexessupporting

confidence: 81%

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5-Fluoro-1-Methyl-Pyrazol-4-yl-Substituted Nitronyl Nitroxide Radical and Its 3d Metal Complexes: Synthesis, Structure, and Magnetic Properties

Kudryavtseva,

Serykh,

Ugrak

et al. 2023

Crystals

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The metal–radical approach is a well-established synthetic way toward multi-spin systems that relies on the coordination of stable radical ligands with transition metal ions. The advantage offered by the use of paramagnetic ligands is that metal–radical magnetic exchange coupling is direct between the magnetic orbitals of the radical and metal ion. With the aim of further exploring this approach, crystals of four heterspin complexes, [M(hfac)2LF]2 {M = Mn, Co, or Ni and hfac = hexafluoroacetylacetonate} and [Cu(hfac)2LF]n, were obtained using a new fluorinated pyrazolyl-substituted nitronyl nitroxide radical, 4,4,5,5-tetramethyl-2-(5-fluoro-1-methyl-1H-pyrazol-4-yl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (LF) as a ligand. The newly synthesized complexes were fully characterized, including X-ray crystallography and magnetometry. XRD analysis revealed that complexes [M(hfac)2LF]2 have similar dimer structures in which a metal ion is in a six-coordinated environment with four O atoms from the two hfac ligands, one radical O atom, and one pyrazole N atom from ligand LF. Nonetheless, the packing patterns of the complexes were found to be considerably different. In [Mn(hfac)2LF]2, there are no magnetically important short contacts between manganese dimers. By contrast, in [Co(hfac)2LF]2 and [Ni(hfac)2LF]2, there are short contacts between non-coordinate O atoms of nitronyl nitroxide moieties. Magnetic behaviors of [M(hfac)2LF]2 showed that the M ions and the directly coordinated radicals are strongly antiferromagnetically coupled (JMn-ON = −84.1 ± 1.5 cm−1, JCo-ON = −134.3 ± 2.6 cm−1, and JNi-ON = −276.2 ± 2.1 cm−1; H^=−2JS⃑^MS⃑^NO). Notably, the magnetization of [Mn(hfac)2LF]2 having molecular structure proved to be accompanied by hysteresis. The [Cu(hfac)2LF]n complex has a chain-polymer structure with alternating magnetic fragments: three spin exchange clusters {ONO–Cu(II)–ONO} and {Cu(II)} ions. Despite the direct coordination of radicals, its magnetic properties are weakly ferromagnetic (JCu-ON = 14.8 ± 0.3 cm−1).

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Section: Synthesis and Structures Of Complexessupporting

confidence: 81%

Section: Synthesis and Structures Of Complexessupporting

confidence: 81%