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1. Facile proton-coupled electron transfer enabled by coordination-induced E–H bond weakening to boron

   https://doi.org/10.1039/D1CC02832D  

   Wong, Anthony; Chakraborty, Arunavo; Bawari, Deependra; Wu, Guang; Dobrovetsky, Roman; Ménard, Gabriel (January 2021, Chemical Communications)

   null (Ed.)

   We report the facile activation of aryl E–H (ArEH; E = N, O, S; Ar = Ph or C 6 F 5 ) or ammonia N–H bonds via coordination-induced bond weakening to a redox-active boron center in the complex, (1 − ). Substantial decreases in E–H bond dissociation free energies (BDFEs) are observed upon substrate coordination, enabling subsequent facile proton-coupled electron transfer (PCET). A drop of >50 kcal mol −1 in H 2 N–H BDFE upon coordination was experimentally determined. 

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2. An Atomistic Picture of Boron Oxide Catalysts for Oxidative Dehydrogenation Revealed by Ultrahigh Field ¹¹ B– ¹⁷ O Solid-State NMR Spectroscopy

   https://doi.org/10.1021/jacs.2c08237  

   Dorn, Rick W.; Mark, Lesli O.; Hung, Ivan; Cendejas, Melissa C.; Xu, Yijue; Gor’kov, Peter L.; Mao, Wenping; Ibrahim, Faysal; Gan, Zhehong; Hermans, Ive; et al (October 2022, Journal of the American Chemical Society)

   Boron oxide/hydroxide supported on oxidized activated carbon (B/OAC) was shown to be an inexpensive catalyst for the oxidative dehydrogenation (ODH) of propane that offers activity and selectivity comparable to boron nitride. Here, we obtain an atomistic picture of the boron oxide/hydroxide layer in B/OAC by using 35.2 T 11B and 17O solid-state NMR experiments. NMR spectra measured at 35.2 T resolve the boron and oxygen sites due to narrowing of the central-transition powder patterns. A 35.2 T 2D 11B{17O} dipolar heteronuclear correlation NMR spectrum revealed the structural connectivity between boron and oxygen atoms. The approach outlined here should be generally applicable to determine atomistic structures of heterogeneous catalysts containing quadrupolar nuclei. 

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3. Rapid reversible borane to boryl hydride exchange by metal shuttling on the carborane cluster surface

   https://doi.org/10.1039/C7SC01846K  

   Eleazer, Bennett J.; Smith, Mark D.; Popov, Alexey A.; Peryshkov, Dmitry V. (January 2017, Chemical Science)

   In this work, we introduce a novel concept of a borane group vicinal to a metal boryl bond acting as a supporting hemilabile ligand in exohedrally metalated three-dimensional carborane clusters. The (POBOP)Ru(Cl)(PPh 3 ) pincer complex (POBOP = 1,7-OP( i -Pr) 2 - m -2-carboranyl) features extreme distortion of the two-center-two-electron Ru–B bond due to the presence of a strong three-center-two-electron B–H⋯Ru vicinal interaction. Replacement of the chloride ligand with a hydride afforded the (POBOP)Ru(H)(PPh 3 ) pincer complex, which possesses B–Ru, B–H⋯Ru, and Ru–H bonds. This complex was found to exhibit a rapid exchange between hydrogen atoms of the borane and the terminal hydride through metal center shuttling between two boron atoms of the carborane cage. This exchange process, which involves sequential cleavage and formation of strong covalent metal–boron and metal–hydrogen bonds, is unexpectedly facile at temperatures above −50 °C corresponding to an activation barrier of 12.2 kcal mol −1 . Theoretical calculations suggested two equally probable pathways for the exchange process through formally Ru(0) or Ru( iv ) intermediates, respectively. The presence of this hemilabile vicinal B–H⋯Ru interaction in (POBOP)Ru(H)(PPh 3 ) was found to stabilize a latent coordination site at the metal center promoting efficient catalytic transfer dehydrogenation of cyclooctane under nitrogen and air at 170 °C. 

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4. Global Minimum Search and Bonding Analysis of Tl ₂ H _x and Tl ₃ H _y (x=0–6; y=0–5) Series

   https://doi.org/10.1002/cphc.202300332  

   Pozdeev, Anton S.; Rublev, Pavel; Boldyrev, Alexander I.; Rao, Yi (July 2023, ChemPhysChem)

   Abstract A remarkable distinction between boron and carbon hydrides lies in their extremely different bonding patterns and chemical reactivity, resulting in diverse areas of application. Particularly, carbon, characterized by classical two‐center – two‐electron bonds, gives rise to organic chemistry. In contrast, boron forms numerous exotic and non‐intuitive compounds collectively called non‐classical structures. It is reasonable to anticipate that other elements of Group 13 exhibit their own unusual bonding patterns; however, our knowledge of the hydride chemistry for other elements in Group 13 is much more limited, especially for the heaviest stable element, thallium. In this work, we performed a conformational analysis of Tl₂H_xand Tl₃H_y(x=0–6, y=0–5) series via Coalescence Kick global minimum search algorithm, DFT, andab initioquantum chemistry methods; we investigated the bonding pattern using the AdNDP algorithm, thermodynamic stability, and stability toward electron detachment. All found global minimum structures are classified as non‐classical structures featuring at least one multi‐center bond. 

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5. Mitigation of Electromigration in Metal Interconnects via Hexagonal Boron Nitride as an Ångström‐Thin Passivation Layer

   https://doi.org/10.1002/aelm.202100002  

   Jeong, Yunjo; Douglas, Ossie; Misra, Utkarsh; Tanjil, Md Rubayat‐E; Watanabe, Kenji; Taniguchi, Takashi; Wang, Michael Cai (April 2021, Advanced Electronic Materials)

   Abstract Electromigration in metal interconnects remains a significant challenge in the continued scaling of integrated circuits towards ever‐smaller single‐nanometer nodes. Conventional damascene architectures of barrier/liner layers and conducting metal cause inevitable compromises between device performance and feature dimensions. In contrast to contemporary barrier/liner materials (e.g., Co, Ta, and Ru), an ultrathin passivation layer that can effectively mitigate electromigration is needed. At the ultimate atomically‐thin limit, 2D materials are promising candidates given their exceptional mechanical properties and impermeability. Here, a facile and effective approach is presented to mitigating electromigration in copper (Cu) interconnects via passivation with insulating monolayer 2D hexagonal boron nitride (hBN). The hBN‐passivated Cu interconnects, compared to otherwise identical but bare Cu interconnects, exhibit on average a >20% higher breakdown current density and a >2600% longer lifetime (at a high current density of 5.4 × 10⁷A cm⁻²). Post‐mortem metrology elucidates uniform conformal contact between the hBN‐passivated Cu interface and common failure features due to electromigration. 

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