13269-57-3Relevant articles and documents
Oxidation and reduction of bis(imino)pyridine iron dinitrogen complexes: Evidence for formation of a chelate trianion.
Tondreau, Aaron M.,Stieber, S. Chantal E.,Milsmann, Carsten,Lobkovsky, Emil,Weyhermüller, Thomas,Semproni, Scott P.,Chirik, Paul J.
, p. 635 - 646 (2013)
Oxidation and reduction of the bis(imino)pyridine iron dinitrogen compound, (iPrPDI)FeN2 (iPrPDI = 2,6-(2,6- iPr2-C6H3-N=CMe)2C 5H3N) has been examined to determine whether the redox events are metal or ligand based. Treatment of (iPrPDI)FeN 2 with [Cp2Fe][BArF4] (BAr F4 = B(3,5-(CF3)2-C 6H3)4) in diethyl ether solution resulted in N2 loss and isolation of [(iPrPDI)Fe(OEt 2)][BArF4]. The electronic structure of the compound was studied by SQUID magnetometry, X-ray diffraction, EPR and zero-field 57Fe M?ssbauer spectroscopy. These data, supported by computational studies, established that the overall quartet ground state arises from a high spin iron(II) center (SFe = 2) antiferromagnetically coupled to a bis(imino)pyridine radical anion (SPDI = 1/2). Thus, the oxidation event is principally ligand based. The one electron reduction product, [Na(15-crown-5)][(iPrPDI)FeN2], was isolated following addition of sodium naphthalenide to (iPrPDI)FeN2 in THF followed by treatment with the crown ether. Magnetic, spectroscopic, and computational studies established a doublet ground state with a principally iron-centered SOMO arising from an intermediate spin iron center and a rare example of trianionic bis(imino)pyridine chelate. Reduction of the iron dinitrogen complex where the imine methyl groups have been replaced by phenyl substituents, (iPrBPDI)Fe(N2)2 resulted in isolation of both the mono-and dianionic iron dinitrogen compounds, [( iPrBPDI)FeN2]- and [(iPrBPDI) FeN2]2-, highlighting the ability of this class of chelate to serve as an effective electron reservoir to support neutral ligand complexes over four redox states.
Exploiting Charge-Transfer States for Maximizing Intersystem Crossing Yields in Organic Photoredox Catalysts
Sartor, Steven M.,McCarthy, Blaine G.,Pearson, Ryan M.,Miyake, Garret M.,Damrauer, Niels H.
supporting information, p. 4778 - 4781 (2018/04/17)
A key feature of prominent transition-metal-containing photoredox catalysts (PCs) is high quantum yield access to long-lived excited states characterized by a change in spin multiplicity. For organic PCs, challenges emerge for promoting excited-state intersystem crossing (ISC), particularly when potent excited-state reductants are desired. Herein, we report a design exploiting orthogonal π-systems and an intermediate-energy charge-transfer excited state to maximize ISC yields (ΦISC) in a highly reducing (E0? = -1.7 V vs SCE), visible-light-absorbing phenoxazine-based PC. Simple substitution of N-phenyl for N-naphthyl is shown to dramatically increase ΦISC from 0.11 to 0.91 without altering catalytically important properties, such as E0?.
Formal Synthesis of Bioactive Indole Alkaloids Eburnamonine, Eburnaminol, and Vindeburnol
Mondal, Pravat,Argade, Narshinha P.
, p. 1849 - 1856 (2017/04/06)
Starting from (±)-3-acetoxyglutarimide, diastereoselective formal synthesis of indole alkaloids (±)-eburnamonine, (±)-eburnaminol, and (±)-vindeburnol have been demonstrated via a common intermediate (±)-1-hydroxy-12-tosyl-2,3,6,7,12,12b-hexahydroindolo[2,3-a]quinolizin-4(1H)-one in very good overall yields. The acetoxy group from (±)-3-acetoxyglutarimide was first used to induce the diastereoselectivity and also as a latent source of ketone carbonyl group. The stereoselective eliminations, reductions, and intramolecular cyclizations were the involved key steps.
