New Cascade Syntheses of Nitronyl Nitroxides and a New Synthetic Approach to Imino Nitroxides

Tretyakov, Evgeny V.; Толстиков, С. Е.; Mareev, A. V.; Медведева, А. С.; Романенко, Г. В.; Stass, Dmitri V.; Bogomyakov, A. S.; Овчаренко, В. И.

doi:10.1002/ejoc.200801237

Cited by 14 publications

(5 citation statements)

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“…Although the mechanistic details of the deoxygenation pathway are uncertain, the conversion of diradical 1 to iminonitroxide 2 was confirmed by monitoring the reaction by TLC. The oxidative deoxygenation path can be supported by the following observations in the literatures: Nitronyl nitroxides can be converted into iminonitroxides in the presence of an electron-deficient and oxygen-accepting TCNQ and/or TCNQF 4 , in the reaction with chlorine gas followed by treatment with ethanol, and also in the reaction with MnO 2 in nitromethane . In the next step, diradical 2 would be reduced under the complexation conditions to give the paramagnetic anion 3 .…”

Section: Resultsmentioning

confidence: 69%

“…The oxidative deoxygenation path can be supported by the following observations in the literatures: Nitronyl nitroxides can be converted into iminonitroxides in the presence of an electrondeficient and oxygen-accepting TCNQ and/or TCNQF 4 , 15 in the reaction with chlorine gas followed by treatment with ethanol, 16 and also in the reaction with MnO 2 in nitromethane. 17 In the next step, diradical 2 would be reduced under the complexation conditions to give the paramagnetic anion 3. The occurrence of this step is supported by the formation of the same complex [Cu 2 (hfac and [Cu 2 (hfac) 2 •3 2 •Cu(hfac) 2 ] n .…”

Section: Resultsmentioning

confidence: 99%

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Preparation and Magnetic Properties of Metal-Complexes from N-t-Butyl-N-oxidanyl-2-amino-(nitronyl nitroxide)

et al. 2013

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Metal complexation reactions of N-t-butyl-N-oxidanyl-2-amino(nitronyl nitroxide) diradical (1) with M(hfac)2 (M: Mn or Cu) were investigated. These reactions were found to be very sensitive to the type of metal ion employed. Complex [Mn(hfac)2·1], consisting of Mn(hfac)2 and diradical 1, was readily prepared by mixing the components. However, the reaction of Cu(hfac)2 with 1 or N-t-butyl-N-oxidanyl-2-amino(iminonitroxide) diradical (2) involved the reduction of the diradical to the N-t-butyl-N-oxidanide-2-amino(iminonitroxide) radical anion (3) and finally produced the polymer-chain complex [Cu2(hfac)2·32·Cu(hfac)2]n. The structures of these complexes were elucidated by X-ray analysis, and their magnetic properties were investigated in detail. The temperature dependence of χpT (χp: magnetic susceptibility) for [Mn(hfac)2·1] exhibited a strong antiferromagnetic interaction (H = -2JS1·S2, J/kB = -217 K) between the Mn(II) spin (S = 5/2) and the diradical 1 spin (S = 1). However, the χpT-T plots for [Cu2(hfac)2·32·Cu(hfac)2]n indicated the presence of several magnetic interactions: a large ferromagnetic interaction (J/kB = 510 K) between iminonitroxide 3 and the imino-coordinating Cu(II) atom, a moderately large ferromagnetic interaction (J/kB = 58 K) between the iminonitroxide and (iminonitroxide oxygen)-coordinating Cu(hfac)2, and a weak antiferromagnetic interaction (J/kB = -1.4 K) between the two Cu(hfac)-3 moieties within a Cu2O2 square.

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Section: Resultsmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Preparation and Magnetic Properties of Metal-Complexes from N-t-Butyl-N-oxidanyl-2-amino-(nitronyl nitroxide)

et al. 2013

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“…While in one instance these radical-pairing interactions have been employed successfully as a novel recognition motif to template the formation of a [2]rotaxane, the redox-activated bistability of BIPY •+ units also affords these compounds opportunities to become integrated into nanoelectromechanical systems (NEMs). In addition, the radical nature of BIPY •+ units can lead to functional composite materials with a variety of potential applications, e.g., paramagnetic materials and conductive molecular electronic devices . However, these potential applications have remained, for the most part, unexplored, probably at least in part on account of the low resistance of BIPY •+ radical cations to oxidation by atmospheric O 2 .…”

Section: Introductionmentioning

confidence: 99%

Mechanical Bond-Induced Radical Stabilization

Zhu

Fahrenbach

et al. 2012

J. Am. Chem. Soc.

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A homologous series of [2]rotaxanes, in which cyclobis(paraquat-p-phenylene) (CBPQT(4+)) serves as the ring component, while the dumbbell components all contain single 4,4'-bipyridinium (BIPY(2+)) units centrally located in the midst of oligomethylene chains of varying lengths, have been synthesized by taking advantage of radical templation and copper-free azide-alkyne 1,3-dipolar cycloadditions in the formation of their stoppers. Cyclic voltammetry, UV/vis spectroscopy, and mass spectrometry reveal that the BIPY(•+) radical cations in this series of [2]rotaxanes are stabilized against oxidation, both electrochemically and by atmospheric oxygen. The enforced proximity between the BIPY(2+) units in the ring and dumbbell components gives rise to enhanced Coulombic repulsion, destabilizing the ground-state co-conformations of the fully oxidized forms of these [2]rotaxanes. The smallest [2]rotaxane, with only three methylene groups on each side of its dumbbell component, is found to exist under ambient conditions in a monoradical state, a situation which does not persist in acetonitrile solution, at least in the case of its longer analogues. (1)H NMR spectroscopy reveals that the activation energy barriers to the shuttling of the CBPQT(4+) rings over the BIPY(2+) units in the dumbbells increase linearly with increasing oligomethylene chain lengths across the series of [2]rotaxanes. These findings provide a new way of producing highly stabilized BIPY(•+) radical cations and open up more opportunities to use stable organic radicals as building blocks for the construction of paramagnetic materials and conductive molecular electronic devices.

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“…Each oxidation conditions were tested to find the best oxidative conditions. The suspension of an excess of MnO 2 or PbO 2 in solvent like CH 2 Cl 2 , CHCl 3 or toluene leads to a heterogeneous oxidation, whereas oxidation by a drop‐wise addition of NaIO 4 (aq.) requires a bi‐phasic solution of a water‐immiscible solvent such as CH 2 Cl 2 or diethyl ether and saturated NaHCO 3 (aq.)…”

Section: Resultsmentioning

confidence: 99%

“…The suspensiono f an excesso fM nO 2 [27] or PbO 2 [28] in solvent like CH 2 Cl 2 ,C HCl 3 or toluene leads to ah eterogeneous oxidation, whereas oxidation by adrop-wise addition of NaIO 4 (aq.) )/ MeOH/C u(OAc) 2 mixture are among the common oxidants utilized in the Ullman pathway.E ach oxidation conditions were tested to find the best oxidative conditions.…”

Section: Oxidation Optimizationmentioning

confidence: 99%

Revisiting the Ullman's Radical Chemistry for Phthalocyanine Derivatives

Fidan

Luneau

Ahsen

et al. 2018

Chemistry A European J

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Phthalocyanine derivatives do not cease to gain attention due to their numerous properties and applications (e.g., sensor, PDT). This makes them a unique scaffold for the design of new material. In this context, we were interested to develop the synthesis of an imino nitroxide-substituted phthalocyanine by Ullman's procedure; a challenge due to the intrinsic low solubility of most phthalocyanine derivative in much solvents. To overcome this solubility problem, we designed a phthalocyanine with bulky neopentyl substituents in peripheral positions as counterpart to the imino nitroxide moieties. The imino nitroxide-substituted phthalocyanine was obtained by condensation of a monoformyl-substituted phthalocyanine with 2,3-bis(hydroxylamino)-2,3-dimethylbutane in refluxing THF-MeOH (2:1) mixture in the presence of p-toluenesulfonic acid monohydrate, follow by oxidation with PbO . Characterization was performed by electrochemistry, UV/Vis and EPR spectroscopy in solution as well as SQUID in solid state.

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New Cascade Syntheses of Nitronyl Nitroxides and a New Synthetic Approach to Imino Nitroxides

Cited by 14 publications

References 38 publications

Preparation and Magnetic Properties of Metal-Complexes from N-t-Butyl-N-oxidanyl-2-amino-(nitronyl nitroxide)

Preparation and Magnetic Properties of Metal-Complexes from N-t-Butyl-N-oxidanyl-2-amino-(nitronyl nitroxide)

Mechanical Bond-Induced Radical Stabilization

Revisiting the Ullman's Radical Chemistry for Phthalocyanine Derivatives

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