First coordination compounds based on a bis(imino nitroxide) biradical and 4f metal ions: synthesis, crystal structures and magnetic properties

Reis, Samira G.; Briganti, Matteo; Martins, Daniel O. T. A.; Akpinar, Handan; Calancea, Sergiu; Guedes, Guilherme P.; Soriano, S.; Andruh, Marius; Cassaro, Rafael A. Allão; Lahti, Paul M.; Totti, Federico; Vaz, Maria G. F.

doi:10.1039/c5dt04469c

“…The spin–spin interaction between the stable free radicals such as nitronylnitroxides (NN), tert -butylnitroxides, iminonitroxides (IN), and verdazyl (VZ) can be fine-tuned through their combination with conjugated oligomers. − Previously reported NN biradicals were built upon biphenyl, terpyridine, pyrene, and tolane as a π-bridge, and their optical, electrochemical, EPR, and magnetic properties were studied.…”

Section: Introductionmentioning

confidence: 99%

Mixed Phenyl and Thiophene Oligomers for Bridging Nitronyl Nitroxides

Kolanji

¹

,

Ravat

²

,

Bogomyakov

³

et al. 2017

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The synthesis of four nitronyl nitroxide (NN) biradicals is described which are conjugatively linked through p-ter-phenyl (PPP), ter-thiophene (TTT) and alternating phenylene (P) and thiophene (T) units as PTP and TPT. We first utilized Suzuki and Stille coupling reactions through protection and deprotection protocols to synthesize these (NN) biradicals. Single crystals were efficiently grown for radical precursors of 3, 5, 6, PPP-NNSi, PTP-NNSi, and final biradicals of TTT-NN, TPT-NN, and PPP-NN, whose structures and molecular packing were examined by X-ray diffraction studies. As a result, much smaller torsions between the NN and thiophene units (∼10°) in TTT-NN and TPT-NN than for NN and phenyl units (∼29°) in PPP-NN were observed due to smaller hindrance for a five vs a six membered ring. All four biradicals TTT-NN, TPT-NN, PTP-NN, and PPP-NN were investigated by EPR and optical spectroscopy combined with DFT calculations. The magnetic susceptibility was studied by SQUID measurements for TTT-NN and TPT-NN. The intramolecular exchange interactions for TPT-NN and TTT-NN were found in good agreement with the ones calculated by broken symmetry DFT calculations.

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“…Many possibilities remain unexplored using these spin carriers to alter the coordination structural and magnetic behavior because few coordination compounds containing INR type biradicals have been reported. 14 , 15 …”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Supramolecular Architectures with Mn^IIIons Assembled from Hydrogen Bonding Interactions: Crystal Structures and Antiferromagnetic Properties

Gao

¹

,

Wang

²

,

Gao

³

et al. 2022

ACS Omega

2

0

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Two novel cocrystal Mn II compounds were successfully synthesized. The composition of two kinds crystals correspond to [Mn(hfac) 2 L a 2 ·Mn(hfac) 2 L a (H 2 O)·Mn(hfac) 2 (H 2 O) 2 ] ( 1 ) and [Mn(hfac) 2 L b 2 ·Mn(hfac) 2 (H 2 O) 2 ·0.5(C 6 H 14 )] ( 2 ) [L a = 1,3-bis(1′-oxyl-3′-oxido-4′,4′,5′,5′-tetramethyl-4,5-dihydro-1 H -imidazol-2-y1)benzene; L b = 1-(1′-oxyl-4′,4′,5′,5′-tetramethylimidazolin-2-yl)-3-(1′-oxyl-3′-oxo-4′,4′,5′,5′-tetramethylimidazolin-2-yl)benzene; hfac = hexafluoroacetylacetonato). Surprisingly, the compounds were not polymeric or clusters but, more interestingly, different ratio biradical–metal coordination compound cocrystals. The extensive intramolecular H-bonds are the cause of formation of the cocrystal structures by assembly in the two manganese(II) derivatives; and another factor is the halogen bonds between CF 3 of hfac groups. Furthermore, three-dimensional supramolecular architectures were formed. The magnetic susceptibility of both compounds showed strong antiferromagnetic interactions involving the coordinated radical unit and the metal and lesser contribution from ferromagnetic interactions between the radical units. For compound 1 , a good fit was obtained for g Mn = 2.08, g rad = 2.00 (fixed), J 1 = −294.3 cm –1 , J 2 = 6.2 cm –1 and J 3 = 10.8 cm –1 . A reasonable fit for compound 2 was obtained for g Mn = 2.04, g rad = 2.00 (fixed), J 1 ′ = −273.4 cm –1 and J 2 ′ = 8.6 cm –1 .

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“…The combination of different spin carriers is a valuable synthetic strategy to obtain molecular magnetic materials. Indeed, most of the 3-D molecule-based magnets and single chain magnets (SCMs), as well as numerous single molecule magnets (SMMs) are 3d– n d, n d–4f, 2p– n d, and 2p–4f heterobispin complexes. Particular pairs of spin carriers are chosen in order to afford large spin values of the ground state with a large magnetic anisotropy (especially for SMMs and SCMs) and, hopefully, to add an exchange coupling interaction acting as an effective field on the metal/rare earth ion(s) and, therefore, able to overcome the fast relaxation shortcomings derived by the quantum tunneling process.…”

Section: Introductionmentioning

confidence: 99%

SMM Behavior Tuned by an Exchange Coupling LEGO Approach for Chimeric Compounds: First 2p–3d–4f Heterotrispin Complexes with Different Metal Ions Bridged by One Aminoxyl Group

Pătraşcu

¹

,

Briganti

²

,

Soriano

³

et al. 2019

Self Cite

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Coordination compounds containing three different spin carriers (2p, 3d, and 4f), with the general formula [M II Dy III (LH)-(hfac) 5 ] (M = Co, Ni, Mn, Zn), have been obtained using Mannich ligands decorated with a nitronyl−nitroxide fragment. The synthetic approach is general and leads to binuclear 3d−4f complexes, the two metal ions being bridged by one aminoxyl group and by one oxygen atom arising from a hfac − ligand. Triangular spin topology affords significant 2p−3d, 3d−4f, and 2p−4f exchange interactions. For the [Co II Dy III Rad] derivative obtained using a nitronyl−nitroxide chiral ligand, a high energy barrier (∼200 cm −1 ) and a slow relaxation behavior below 30 K were found and rationalized by ab initio calculations. The improvement of magnetic properties comes from the synergy of optimal single ions properties and exchange couplings contributions where the Co II −Rad interaction becomes the leading one. The role played by this interaction is clearly proved by the investigation of the magnetic properties of the [Zn II Dy III Rad] derivative, with a much lower energy barrier (12.7 cm −1 ) and by the lack of SMM behavior of the previously reported [Co II Dy III Rad] compound (Chem. Commun. 2017, 53, 6504), with a linear topology of spin carriers and a negligible Co II −Rad interaction.

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First coordination compounds based on a bis(imino nitroxide) biradical and 4f metal ions: synthesis, crystal structures and magnetic properties

Cited by 33 publications

References 49 publications

Mixed Phenyl and Thiophene Oligomers for Bridging Nitronyl Nitroxides

Mixed Phenyl and Thiophene Oligomers for Bridging Nitronyl Nitroxides

Three-Dimensional Supramolecular Architectures with Mn^IIIons Assembled from Hydrogen Bonding Interactions: Crystal Structures and Antiferromagnetic Properties

SMM Behavior Tuned by an Exchange Coupling LEGO Approach for Chimeric Compounds: First 2p–3d–4f Heterotrispin Complexes with Different Metal Ions Bridged by One Aminoxyl Group

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First coordination compounds based on a bis(imino nitroxide) biradical and 4f metal ions: synthesis, crystal structures and magnetic properties

Cited by 33 publications

References 49 publications

Mixed Phenyl and Thiophene Oligomers for Bridging Nitronyl Nitroxides

Mixed Phenyl and Thiophene Oligomers for Bridging Nitronyl Nitroxides

Three-Dimensional Supramolecular Architectures with MnIIIons Assembled from Hydrogen Bonding Interactions: Crystal Structures and Antiferromagnetic Properties

SMM Behavior Tuned by an Exchange Coupling LEGO Approach for Chimeric Compounds: First 2p–3d–4f Heterotrispin Complexes with Different Metal Ions Bridged by One Aminoxyl Group

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Product

Resources

About

Three-Dimensional Supramolecular Architectures with Mn^IIIons Assembled from Hydrogen Bonding Interactions: Crystal Structures and Antiferromagnetic Properties