Almost all phase-change memory materials (PCM) contain chalcogen atoms, and their chemical bonds have been denoted both as 'electron-deficient' [sometimes referred to as 'metavalent'] and 'electron-rich' ['hypervalent', multicentre]. The latter involve lone-pair electrons. We have performed calculations that can discriminate unambiguously between these two classes of bond and have shown that PCM have electron-rich, 3c-4e ('hypervalent') bonds. Plots of charge transferred between () and shared with () neighbouring atoms cannot on their own distinguish between 'metavalent' and 'hypervalent' bonds, both of which involve single-electron bonds. PCM do not exhibit 'metavalent' bonding and are not electron-deficient; the bonding is electron-rich of the 'hypervalent' or multicentre type.
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http://dx.doi.org/10.1088/1361-648X/ad46d6 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
School of Chemistry, Cardiff University, Cardiff, CF10 3AT, Cymru/Wales, UK.
Despite the remarkable advancements in hypervalent iodine chemistry, exploration of bromine and chlorine analogues remains in its infancy due to their difficult synthesis. Herein, we introduce six-membered cyclic λ-bromanes and λ-chloranes. Through single-crystal X-ray structural analyses and conformational studies, we delineate the crucial bonding patterns pivotal for the thermodynamic stability of these compounds.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Laboratory of Advanced Materials, Aqueous Battery Center, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, School of Chemistry and Materials, Fudan University, Shanghai, 200433, P. R. China.
Tellurium (Te), with its rich valence states (-2 to +6), could endow aqueous batteries with potentially high specific capacity. However, achieving complete and stable hypervalent Te/Te electrochemistry in an aqueous environment poses significant challenges, owing to the sluggish reduction kinetics, easy dissolution of Te species, and a controversial energy storage mechanism. Herein, we demonstrate a crystallographic regulation strategy for robust aqueous Te redox electrochemistry.
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University, Tomsk 634050, Russian Federation.
We report the synthesis of novel N-coordinated -iodanes as a unique class of hypervalent iodine compounds. X-ray diffraction analysis revealed their intriguing (pseudo)cyclic structure, showcasing distinctive N⋯I-secondary bonding interactions. We demonstrate the generation of reactive diacetoxy derivatives, which exhibits remarkable efficacy in alcohol oxidation reactions.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Department of Chemistry, Johns Hopkins University; Baltimore, Maryland 21218, United States.
The trifluoromethyl (-CF) group represents a highly prevalent functionality in pharmaceuticals. Over the past few decades, significant advances have been made in the development of synthetic methods for trifluoromethylation. In contrast, there are currently no metalloenzymes known to catalyze the formation of C(sp)-CF bonds.
View Article and Find Full Text PDFActa Crystallogr C Struct Chem
December 2024
Universidad Nacional Autónoma de México, Instituto de Química, Ciudad Universitaria, Ciudad de México, 04510, Mexico.
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