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1. Epitaxial stabilization versus interdiffusion: synthetic routes to metastable cubic HfO 2 and HfV 2 O 7 from the core–shell arrangement of precursors

   https://doi.org/10.1039/c9nr07316g  

   Fleer, Nathan A. ; Thomas, Melonie P. ; Andrews, Justin L. ; Waetzig, Gregory R. ; Gonzalez, Oscar ; Liu, Guan-Wen ; Guiton, Beth S. ; Banerjee, Sarbajit ( November 2019 , Nanoscale)

   Metastable materials that represent excursions from thermodynamic minima are characterized by distinctive structural motifs and electronic structure, which frequently underpins new function. The binary oxides of hafnium present a rich diversity of crystal structures and are of considerable technological importance given their high dielectric constants, refractory characteristics, radiation hardness, and anion conductivity; however, high-symmetry tetragonal and cubic polymorphs of HfO 2 are accessible only at substantially elevated temperatures (1720 and 2600 °C, respectively). Here, we demonstrate that the core–shell arrangement of VO 2 and amorphous HfO 2 promotes outwards oxygen diffusion along an electropositivity gradient and yields an epitaxially matched V 2 O 3 /HfO 2 interface that allows for the unprecedented stabilization of the metastable cubic polymorph of HfO 2 under ambient conditions. Free-standing cubic HfO 2 , otherwise accessible only above 2600 °C, is stabilized by acid etching of the vanadium oxide core. In contrast, interdiffusion under oxidative conditions yields the negative thermal expansion material HfV 2 O 7 . Variable temperature powder X-ray diffraction demonstrate that the prepared HfV 2 O 7 exhibits pronounced negative thermal expansion in the temperature range between 150 and 700 °C. The results demonstrate the potential of using epitaxial crystallographic relationships to facilitate preferential nucleation of otherwise inaccessible metastable compounds. 

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2. Monosubstituted, Anionic Imidazolyl Ligands from N−H NHC Precursors and Their Activity in Pd‐Catalyzed Cross‐Coupling Reactions

   https://doi.org/10.1002/adsc.202000483  

   Martinez, Erin E. ; Jensen, Christopher A. ; Larson, Alexandra J. S. ; Kenney, Karissa C. ; Clark, Kyle J. ; Nazari, S. Hadi ; Valdivia‐Berroeta, Gabriel A. ; Smith, Stacey J. ; Ess, Daniel H. ; Michaelis, David J. ( June 2020 , Advanced Synthesis & Catalysis)

   We report that treatment of several 2‐diphenylphosphinoimidazoles with Pd(II) salts generates monosubstituted N−H NHC−Pd complexes via insertion into the C−P bond. Removal of the N−H proton in situ leads to anionic (X‐type) or imidazolyl‐Pd complexes that are highly stable and catalytically active, achieving up to 340,000 turnovers at 1 ppm catalyst loading in Suzuki‐Miyaura reactions. DFT‐calculated Tolman electronic parameters for the sterically small ligands suggest that these ligands are significantly more donating than traditional NHCs, which provides a rationale for rapid cross‐coupling catalysis. Excellent reactivity is also demonstrated in Sonogashira reactions.

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3. New Synthetic Routes to Iron–Sulfur Clusters: Deciphering the Repair Chemistry of [2Fe–2S] Clusters from Mononitrosyl Iron Complexes

   https://doi.org/10.1021/acs.inorgchem.5b00961  

   Fitzpatrick, Jessica ; Kim, Eunsuk ( November 2015 , Inorganic Chemistry)
4. Anionic Amino-Cope Rearrangement Cascade Synthesis of 2,4-Substituted Benzoate Esters from Acyclic Building Blocks

   https://doi.org/10.1021/acs.orglett.2c03134  

   Qureshi, M. Haziq ; Njardarson, Jon T. ( October 2022 , Organic letters)
5. Synthesis of Five-Membered Iodine–Nitrogen Heterocycles from Benzimidazole-Based Iodonium Salts

   https://doi.org/10.1021/acs.joc.8b01995  

   Vlasenko, Yulia A. ; Postnikov, Pavel S. ; Trusova, Marina E. ; Shafir, Alexandr ; Zhdankin, Viktor V. ; Yoshimura, Akira ; Yusubov, Mekhman S. ( September 2018 , The Journal of Organic Chemistry)