Isolation and structural characterization of hypervalent electron-rich pentacoordinate nitrogen species have not been achieved despite continuous attempts for over a century. Herein we report the first synthesis and isolation of air stable hypervalent electron-rich pentacoordinate nitrogen cationic radical () species from oxidation of their corresponding neutral () species. In the cationic radical species, the nitrogen centers adopt a trigonal bipyramidal geometry featuring a 3-center-5-electron hypervalent attractive interaction. The combination of single crystal X-ray diffraction analysis and computational studies revealed weak N-O interactions between the central nitrogen cation and oxygen atoms. This successful design strategy and isolation of air-stable pentacoordinate hypervalent nitrogen species allow further investigations on reactivity and properties resulting from these unusually weakly coordinating interactions in nitrogen compounds.
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http://dx.doi.org/10.1039/d0sc00002g | DOI Listing |
J Am Chem Soc
September 2024
Department of Chemistry & Biochemistry, University of Minnesota Duluth, Duluth, Minnesota 55812, United States.
Porphyrin dyes with strong push-pull type intramolecular charge transfer (ICT) character and broad absorption across the visible spectrum are reported. This combination of properties has been achieved by functionalizing the periphery of hypervalent and highly electron-deficient phosphorus(V) and antimony(V) centered porphyrins with electron-rich triphenylamine (TPA) groups. As a result of the large difference in electronegativity between the porphyrin ring and the peripheral groups, their absorption profiles show several strong charge transfer transitions, which in addition to the porphyrin-centered π → π* transitions, make them panchromatic black dyes with high absorption coefficients between 200 and 800 nm.
View Article and Find Full Text PDFChemistry
October 2024
CNRS, Bordeaux INP, ISM, UMR 5255, University of Bordeaux, F-33400, Talence, France.
The Cu-catalyzed Ullmann-Goldberg cross-coupling between aryl iodides and oxamates is shown to afford the corresponding N-aryloxamates with yields ranging from moderate to excellent, when the oxamate precursor incorporates a bulky tertiary alkyl group effectively preventing product degradation under the strongly basic reaction conditions. The final oxamic acids are then generated through the acid hydrolysis of the oxamate in high yields. These acids were then converted into urethanes using PIDA under thermal conditions or a visible-light Fe-LMCT process.
View Article and Find Full Text PDFMaterials (Basel)
June 2024
Universidad de Burgos, Hospital del Rey, 09001 Burgos, Spain.
In the last few years, a controversy has been raised regarding the nature of the chemical bonding present in phase change materials (PCMs), many of which are minerals such as galena (PbS), clausthalite (PbSe), and altaite (PbTe). Two opposite bonding models have claimed to be able to explain the extraordinary properties of PCMs in the last decade: the hypervalent (electron-rich multicenter) bonding model and the metavalent (electron-deficient) bonding model. In this context, a third bonding model, the electron-deficient multicenter bonding model, has been recently added.
View Article and Find Full Text PDFOrg Lett
May 2024
Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Arbuzova Street 8, Kazan 420088, Russian Federation.
In contrast to hypervalent iodine compounds, the chemistry of their sulfur analogues has been considerably less explored. Herein, we report the direct C-H bond thiolation of electron-rich heterocycles, arenes, and 1,3-dicarbonyls by dichlorosulfuranes under mild conditions. Mechanistic studies and density functional theory calculations suggest the radical chain mechanism of the disclosed transformation.
View Article and Find Full Text PDFBeilstein J Org Chem
May 2024
College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1, Nojihigashi, Kusatsu Shiga, 525-8577, Japan.
Diaryliodonium(III) salts are versatile reagents that exhibit a range of reactions, both in the presence and absence of metal catalysts. In this study, we developed efficient synthetic methods for the preparation of aryl(TMP)iodonium(III) carboxylates, by reaction of (diacetoxyiodo)arenes or iodosoarenes with 1,3,5-trimethoxybenzene in the presence of a diverse range of organocarboxylic acids. These reactions were conducted under mild conditions using the trimethoxyphenyl (TMP) group as an auxiliary, without the need for additives, excess reagents, or counterion exchange in further steps.
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