Metal-ligand ferromagnetic exchange interactions in heteroligand bis-o-semiquinonato nickel complexes with 2,2′-dipyridine and 1,10-phenanthroline

Bubnov, M. P.; Teplova, Irina; Черкасова, А. В.; Баранов, Е. В.; Fukin, Georgy K.; Романенко, Г. В.; Bogomyakov, A. S.; Starikov, А. G.; Cherkasov, V. K.; Абакумов, Г. А.

doi:10.1016/j.poly.2018.10.071

Cited by 15 publications

(4 citation statements)

References 28 publications

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“…Such a result was achieved in the course of a reaction between 3,6-di-tert-butyl-o-benzosemiquinonato Ni II derivative and 2,2 -bipyridine under evacuated conditions. As it can be expected, an effective overlapping of the metal and ligand orbitals was observed in the case of this octahedral complex [62].…”

Section: Introductionsupporting

confidence: 79%

“…It is a remarkable fact that using of the same diimine and catechol ligands can form not only the square-planar aforementioned Ni II compound (LL'CT chromophore). The six-coordinated complex consists of two 3,6-di-tert-butyl-o-benzosemiquinone radicals, and a neutral diimine ligand [62] can be obtained too. Such a result was achieved in the course of a reaction between 3,6-di-tert-butyl-o-benzosemiquinonato Ni II derivative and 2,2 -bipyridine under evacuated conditions.…”

Section: Introductionmentioning

confidence: 99%

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Square-Planar Heteroleptic Complexes of α-Diimine-NiII-Catecholate Type: Intramolecular Ligand-to-Ligand Charge Transfer

et al. 2021

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Two heteroleptic NiII complexes combined the redox-active catecholate and 2,2′- bipyridine ligand platforms were synthesized to observe a photoinduced intramolecular ligand-to-ligand charge transfer (LL’CT, HOMOcatecholate → LUMOα-diimine). A molecular design of compound [NiII(3,6-Cat)(bipy)]∙CH3CN (1) on the base of bulky 3,6-di-tert-butyl-o-benzoquinone (3,6-DTBQ) was an annelation of the ligand with an electron donor glycol fragment, producing derivative [NiII(3,6-Catgly)(bipy)]∙CH2Cl2 (2), in order to influence the energy of LL’CT transition. A substantial longwave shift of the absorption peak was observed in the UV-Vis-NIR spectra of 2 compared with those in 1. In addition, the studied NiII derivatives demonstrated a pronounced negative solvatochromism, which was established using a broad set of solvents. The molecular geometry of both compounds can be ascribed as an insignificantly distorted square-planar type, and the π–π intermolecular stacking of the neighboring α-diimines is realized in a crystal packing. There is a lamellar crystal structure for complex 1, whereas the perpendicular T-motifs with the inter-stacks attractive π–π interactions form the packing of complex 2. The redox-active nature of ligand systems was clearly shown through the electrochemical study: a quasi-reversible one-electron reduction of 2,2′-bipyridine and two reversible successive one-electron oxidative conversations (“catecholate dianion—o-benzosemiquinonato radical anion—neutral o-benzoquinone”) were detected.

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Section: Introductionsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Square-Planar Heteroleptic Complexes of α-Diimine-NiII-Catecholate Type: Intramolecular Ligand-to-Ligand Charge Transfer

et al. 2021

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“…The Ni(1)-N(1) distance is 2.0771(13) Å, which agrees with analogous bond lengths in related nickel complexes containing semiquinonato ligands and a neutral nitrogen-containing ligand ( pyridine, 2,2′-bipyridine, phenanthroline). 49,50 In turn, the Ni(1)-N(2) distance in 2 is 2.1121(14) Å. A slight asymmetry in this ligand coordination has previously been observed in the cobalt complex.…”

Section: Single-crystal X-ray Diffractionmentioning

confidence: 70%

Valence tautomeric interconversion of bis-dioxolene cobalt complex with imino-pyridine functionalized by TEMPO moiety in solid solutions with isostructural nickel analogue: phase transitions and monocrystal destruction

Bubnov,

Zolotukhin,

Fukin

et al. 2024

Dalton Trans.

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“…Copper(II)-and nickel(II)-radical complexes having a direct radical coordination bond are the best documented in the 3d-2p heterospin systems [9,[60][61][62][63][64][65][66][67][68][69][70]. There have been an increasing number of compounds showing a ferromagnetic 3d-2p coupling [75][76][77][78][79][80][81]. It is believed for a long time that axial coordination in copper(II)-nitroxide complexes displays relatively weak ferromagnetic interaction whilst equatorial coordination strong antiferromagnetic interaction [9].…”

Section: Magneto-structural Relationship and Molecular Designmentioning

confidence: 99%

Molecular S = 2 High-Spin, S = 0 Low-Spin and S = 0 ⇄ 2 Spin-Transition/-Crossover Nickel(II)-Bis(nitroxide) Coordination Compounds

et al. 2021

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Heterospin systems have a great advantage in frontier orbital engineering since they utilize a wide diversity of paramagnetic chromophores and almost infinite combinations and mutual geometries. Strong exchange couplings are expected in 3d–2p heterospin compounds, where the nitroxide (aminoxyl) oxygen atom has a direct coordination bond with a nickel(II) ion. Complex formation of nickel(II) salts and tert-butyl 2-pyridyl nitroxides afforded a discrete 2p–3d–2p triad. Ferromagnetic coupling is favored when the magnetic orbitals, nickel(II) dσ and radical π*, are arranged in a strictly orthogonal fashion, namely, a planar coordination structure is characterized. In contrast, a severe twist around the coordination bond gives an orbital overlap, resulting in antiferromagnetic coupling. Non-chelatable nitroxide ligands are available for highly twisted and practically diamagnetic complexes. Here, the Ni–O–N–Csp2 torsion (dihedral) angle is supposed to be a useful metric to describe the nickel ion dislocated out of the radical π* nodal plane. Spin-transition complexes exhibited a planar coordination structure in a high-temperature phase and a nonplanar structure in a low-temperature phase. The gradual spin transition is described as a spin equilibrium obeying the van’t Hoff law. Density functional theory calculation indicates that the energy level crossing of the high- and low-spin states. The optimized structures of diamagnetic and high-spin states well agreed with the experimental large and small torsions, respectively. The novel mechanism of the present spin transition lies in the ferro-/antiferromagnetic coupling switch. The entropy-driven mechanism is plausible after combining the results of the related copper(II)-nitroxide compounds. Attention must be paid to the coupling parameter J as a variable of temperature in the magnetic analysis of such spin-transition materials. For future work, the exchange coupling may be tuned by chemical modification and external stimulus, because it has been clarified that the parameter is sensitive to the coordination structure and actually varies from 2J/kB = +400 K to −1400 K.

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Metal-ligand ferromagnetic exchange interactions in heteroligand bis-o-semiquinonato nickel complexes with 2,2′-dipyridine and 1,10-phenanthroline

Cited by 15 publications

References 28 publications

Square-Planar Heteroleptic Complexes of α-Diimine-NiII-Catecholate Type: Intramolecular Ligand-to-Ligand Charge Transfer

Square-Planar Heteroleptic Complexes of α-Diimine-NiII-Catecholate Type: Intramolecular Ligand-to-Ligand Charge Transfer

Valence tautomeric interconversion of bis-dioxolene cobalt complex with imino-pyridine functionalized by TEMPO moiety in solid solutions with isostructural nickel analogue: phase transitions and monocrystal destruction

Molecular S = 2 High-Spin, S = 0 Low-Spin and S = 0 ⇄ 2 Spin-Transition/-Crossover Nickel(II)-Bis(nitroxide) Coordination Compounds

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