- Crystal structure and vibrational spectra of bis(2?isobutyrylamidophenyl)amine: a redox noninnocent ligand
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The molecular structure of bis(2?isobutyrylamidophenyl)amine (H3LNNN) has been determined from single?crystal X-ray diffraction data. The crystal packing of H3LNNN is governed by the N–H-O and C–H-O hydrogen-bon
- Arslan, Hakan,Aslantatar, Emrah,Gümü?, ?lkay,Macbeth, Cora E.,Sharma, Savita K.,Villanueva, Omar
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p. 1933 - 1951
(2022/01/08)
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- Structure, Spectroscopy, and Reactivity of a Mononuclear Copper Hydroxide Complex in Three Molecular Oxidation States
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Structural, spectroscopic, and reactivity studies are presented for an electron transfer series of copper hydroxide complexes supported by a tridentate redox-active ligand. Single crystal X-ray crystallography shows that the mononuclear [CuOH]1+ core is stabilized via intramolecular H-bonds between the H-donors of the ligand and the hydroxide anion when the ligand is in its trianionic form. This complex undergoes two reversible oxidation processes that produce two metastable "high-valent"CuOH species, which can be generated by addition of stoichiometric amounts of 1e- oxidants. These CuOH species are characterized by an array of spectroscopic techniques including UV-vis absorption, electron paramagnetic resonance (EPR), and X-ray absorption spectroscopies (XAS), which together indicate that all redox couples are ligand-localized. The reactivity of the complexes in their higher oxidation states toward substrates with modest O-H bond dissociation energies (e.g., 4-substitued-2,6-di-tert-butylphenols) indicates that these complexes act as 2H+/2e- oxidants, differing from the 1H+/1e- reactivity of well-studied [CuOH]2+ systems.
- Garcia-Bosch, Isaac,Lancaster, Kyle M.,Macmillan, Samantha N.,Rajabimoghadam, Khashayar,Siegler, Maxime A.,Wu, Tong
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p. 12265 - 12276
(2020/08/06)
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- P-N Cooperative Borane Activation and Catalytic Hydroboration by a Distorted Phosphorous Triamide Platform
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Studies of the stoichiometric and catalytic reactivity of a geometrically constrained phosphorous triamide 1 with pinacolborane (HBpin) are reported. The addition of HBpin to phosphorous triamide 1 results in cleavage of the B-H bond of pinacolborane through addition across the electrophilic phosphorus and nucleophilic N-methylanilide sites in a cooperative fashion. The kinetics of this process of were investigated by NMR spectroscopy, with the determined overall second-order empirical rate law given by ν = -k[1][HBpin], where k = 4.76 × 10-5 M-1 s-1 at 25 °C. The B-H bond activation process produces P-hydrido-1,3,2-diazaphospholene intermediate 2, which exhibits hydridic reactivity capable of reacting with imines to give phosphorous triamide intermediates, as confirmed by independent synthesis. These phosphorous triamide intermediates are typically short lived, evolving with elimination of the N-borylamine product of imine hydroboration with regeneration of the deformed phosphorous triamide 1. The kinetics of this latter process are shown to be first-order, indicative of a unimolecular mechanism. Consequently, catalytic hydroboration of a variety of imine substrates can be realized with 1 as the catalyst and HBpin as the terminal reagent. A mechanistic proposal implicating a P-N cooperative mechanism for catalysis that incorporates the various independently verified stoichiometric steps is presented, and a comparison to related phosphorus-based systems is offered.
- Lin, Yi-Chun,Hatzakis, Emmanuel,McCarthy, Sean M.,Reichl, Kyle D.,Lai, Ting-Yi,Yennawar, Hemant P.,Radosevich, Alexander T.
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p. 6008 - 6016
(2017/05/04)
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- Chemoselective nitro reduction and hydroamination using a single iron catalyst
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The reduction and reductive addition (formal hydroamination) of functionalised nitroarenes is reported using a simple and bench-stable iron(iii) catalyst and silane. The reduction is chemoselective for nitro groups over an array of reactive functionalities (ketone, ester, amide, nitrile, sulfonyl and aryl halide). The high activity of this earth-abundant metal catalyst also facilitates a follow-on reaction in the reductive addition of nitroarenes to alkenes, giving efficient formal hydroamination of olefins under mild conditions. Both reactions offer significant improvements in catalytic activity and chemoselectivity and the utility of these catalysts in facilitating two challenging reactions supports an important mechanistic overlap.
- Zhu, Kailong,Shaver, Michael P.,Thomas, Stephen P.
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p. 3031 - 3035
(2016/05/24)
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- Reversible intermolecular E-H oxidative addition to a geometrically deformed and structurally dynamic phosphorous triamide
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The synthesis and reactivity of geometrically constrained tricoordinate phosphorus (σ3-P) compounds supported by tridentate triamide chelates (N[o-NR-C6H4]23-; R = Me or iPr) are reported.
- Zhao, Wei,McCarthy, Sean M.,Lai, Ting Yi,Yennawar, Hemant P.,Radosevich, Alexander T.
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p. 17634 - 17644
(2015/02/02)
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- Tuning the electronic and steric parameters of a redox-active tris(amido) ligand
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A family of tantalum compounds was prepared to probe the electronic effects engendered by the addition of electron-donating or electron-withdrawing groups to the 4/4′ positions of the redox-active ligand derived from bis(2-isopropylamino-4-X-phenyl)amine
- Munha, Rui F.,Zarkesh, Ryan A.,Heyduk, Alan F.
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p. 11244 - 11255
(2013/10/22)
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- Catalytic dioxygen activation by Co(ii) complexes employing a coordinatively versatile ligand scaffold
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The ligand bis(2-isobutyrylamidophenyl)amine has been prepared and used to stabilize both mononuclear and dinuclear cobalt(ii) complexes. The nuclearity of the cobalt product is regulated by the deprotonation state of the ligand. Both complexes catalytica
- Sharma, Savita K.,May, Philip S.,Jones, Matthew B.,Lense, Sheri,Hardcastle, Kenneth I.,MacBeth, Cora E.
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p. 1827 - 1829
(2011/03/22)
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- A structure-activity study of Ni-catalyzed alkyl-alkyl kumada coupling. Improved catalysts for coupling of secondary alkyl halides
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A structureactivity study was carried out for Ni catalyzed alkylalkyl Kumada-type cross coupling reactions. A series of new nickel(II) complexes including those with tridentate pincer bis(amino)amide ligands (RN2N) and those with bidentate mixed amino-amide ligands (RNN) were synthesized and structurally characterized. The coordination geometries of these complexes range from square planar, tetrahedral, to square pyramidal. The complexes had been examined as precatalysts for cross coupling of nonactivated alkyl halides, particularly secondary alkyl iodides, with alkyl Grignard reagents. Comparison was made to the results obtained with the previously reported Ni pincer complex [( MeN2N)NiCl]. A transmetalation site in the precatalysts is necessary for the catalysis. The coordination geometries and spin-states of the precatalysts have a small or no influence. The work led to the discovery of several well-defined Ni catalysts that are significantly more active and efficient than the pincer complex [(MeN2N)NiCl] for the coupling of secondary alkyl halides. The best two catalysts are [(HNN)Ni(PPh3)Cl] and [(HNN)Ni(2,4-lutidine)Cl]. The improved activity and efficiency was attributed to the fact that phosphine and lutidine ligands in these complexes can dissociate from the Ni center during catalysis. The activation of alkyl halides was shown to proceed via a radical mechanism.
- Ren, Peng,Vechorkin, Oleg,Von Allmen, Kim,Scopelliti, Rosario,Hu, Xile
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p. 7084 - 7095
(2011/06/26)
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- The Reduction of Some 2,2'-Dinitrodiaryl Compounds and Related Compounds by Thiourea S,S-Dioxide (Formamidinesulfinic Acid)
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The reaction of thiourea S,S-dioxide (formamidinesulfinic acid) in ethanolic alkali with 2,2'-dinitrobiphenyl and several related dinitro compounds possessing an-X-bridge (where X = NH, NMe, O and S), located at the 1,1'-positions, has been investigated.With 2,2'-dinitrobiphenyl (which gives good yields of benzocinnoline and its oxides) and, to a minor extent, with 2,2'-dinitrodiphenylamine, an intramolecular reaction occured to give heterocyclic products; with each of the other dinitro compounds, the only product obtained was formed as the result of a Smiles rearrangement.
- Wilshire, John F. K.
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p. 995 - 1001
(2007/10/02)
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- ELECTROCHEMICAL REDUCTION OF 2,2'-DINITRODIPHENYL ETHER AND 2,2'-DINITRODIPHENYLAMINE AT MERCURY CATHODES
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2,2'-Dinitrodiphenyl ether (I) is reduced at less negative potentials than 2,2'-dinitrodiphenylamine (II); the respective mechanisms of their reduction differ essentially. (I) is electrolytically reduced in a single wave with an uptake of eight electrons per molecule, giving rise to a bishydroxylamine intermediate which undergoes an intramolecular disproportionation.The resulting 2-nitroso-2'-amino-diphenyl ether undergoes a chemical follow-up reaction leading on the one hand to dibenzo--(1,4,5)-oxadiazepine, on the other hand to a diphenylamine product (resulting by a chemical rearrangement) which reacts with reductants present in the solution and yields dihydrophenazine.It is merely by chance that in the electrolytical reduction of II dihydrophenazine also results in addition to other products. 2,2'-dinitrodiphenylamine (II) enables here, however, a partial electrolytical reduction in which 2-amino-2'-nitrodiphenylamine is formed in a single 6-electron wave.In the following, more negative wave, is clearly separated only in alkaline media, the other nitro group reduces with an uptake of 4 electrons to an intermediate which eliminates the hydroxylamine group with the corresponding electron pair.The subsequent chemical reaction leads to dihydrophenazine.This substance is the reduced form of an chemically and electrochemically reversible system, this system participates in the chemical reaction of reaction intermediates.Its regeneration readily proceeds at potentials more positive than the reduction potential of II.Phenazine is oxidized in the catholyte by the hydroxylamine set free to phenazine N-oxide.Nitrogen is thus eliminated in its elemental form via hydroxylamine from the substrate molecule.
- Hlavaty, Jaromir,Volke, Jiri,Bakos, Viktor
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p. 379 - 393
(2007/10/02)
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- Metal Template Reactions. XVI. Design and Synthesis of Primary Diamine Ligands with Additional Nitrogen Donor Atoms
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Five new primary diamines (8), (10), (12), (20) and (22) have been synthesized.These compounds contain additional nitrogen donor atoms suitable for metal chelation.An improved preparation of the triamine (6) is also reported.
- Black, David St. C.,Rothnie, Neil E.
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p. 1141 - 1147
(2007/10/02)
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