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1. High‐Resolution Photoelectron Imaging of IrB 3 − : Observation of a π‐Aromatic B 3 + Ring Coordinated to a Transition Metal

   https://doi.org/10.1002/anie.201902406  

   Czekner, Joseph ; Cheung, Ling Fung ; Kocheril, G. Stephen ; Kulichenko, Maksim ; Boldyrev, Alexander I. ; Wang, Lai‐Sheng ( May 2019 , Angewandte Chemie International Edition)

   In a high‐resolution photoelectron imaging and theoretical study of the IrB₃⁻cluster, two isomers were observed experimentally with electron affinities (EAs) of 1.3147(8) and 1.937(4) eV. Quantum calculations revealed two nearly degenerate isomers competing for the global minimum, both with a B₃ring coordinated with the Ir atom. The isomer with the higher EA consists of a B₃ring with a bridge‐bonded Ir atom (C_s,²A′), and the second isomer features a tetrahedral structure (C_3v,²A₁). The neutral tetrahedral structure was predicted to be considerably more stable than all other isomers. Chemical bonding analysis showed that the neutralC_3visomer involves significant covalent Ir−B bonding and weak ionic bonding with charge transfer from B₃to Ir, and can be viewed as an Ir–(η³‐B₃⁺) complex. This study provides the first example of a boron‐to‐metal charge‐transfer complex and evidence of a π‐aromatic B₃⁺ring coordinated to a transition metal.

    

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2. High‐Resolution Photoelectron Imaging of IrB 3 − : Observation of a π‐Aromatic B 3 + Ring Coordinated to a Transition Metal

   https://doi.org/10.1002/ange.201902406  

   Czekner, Joseph ; Cheung, Ling Fung ; Kocheril, G. Stephen ; Kulichenko, Maksim ; Boldyrev, Alexander I. ; Wang, Lai‐Sheng ( May 2019 , Angewandte Chemie)

   In a high‐resolution photoelectron imaging and theoretical study of the IrB₃⁻cluster, two isomers were observed experimentally with electron affinities (EAs) of 1.3147(8) and 1.937(4) eV. Quantum calculations revealed two nearly degenerate isomers competing for the global minimum, both with a B₃ring coordinated with the Ir atom. The isomer with the higher EA consists of a B₃ring with a bridge‐bonded Ir atom (C_s,²A′), and the second isomer features a tetrahedral structure (C_3v,²A₁). The neutral tetrahedral structure was predicted to be considerably more stable than all other isomers. Chemical bonding analysis showed that the neutralC_3visomer involves significant covalent Ir−B bonding and weak ionic bonding with charge transfer from B₃to Ir, and can be viewed as an Ir–(η³‐B₃⁺) complex. This study provides the first example of a boron‐to‐metal charge‐transfer complex and evidence of a π‐aromatic B₃⁺ring coordinated to a transition metal.

    

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3. Al(OR F ) 3 (R F = C(CF 3 ) 3 ) activated silica: a well-defined weakly coordinating surface anion

   https://doi.org/10.1039/C9SC05904K  

   Culver, Damien B. ; Venkatesh, Amrit ; Huynh, Winn ; Rossini, Aaron J. ; Conley, Matthew P. ( February 2020 , Chemical Science)

   Weakly Coordinating Anions (WCAs) containing electron deficient delocalized anionic fragments that are reasonably inert allow for the isolation of strong electrophiles. Perfluorinated borates, perfluorinated aluminum alkoxides, and halogenated carborane anions are a few families of WCAs that are commonly used in synthesis. Application of similar design strategies to oxide surfaces is challenging. This paper describes the reaction of Al(OR F ) 3 *PhF (R F = C(CF 3 ) 3 ) with silica partially dehydroxylated at 700 °C (SiO 2-700 ) to form the bridging silanol Si–OH⋯Al(OR F ) 3 ( 1 ). DFT calculations using small clusters to model 1 show that the gas phase acidity (GPA) of the bridging silanol is 43.2 kcal mol −1 lower than the GPA of H 2 SO 4 , but higher than the strongest carborane acids, suggesting that deprotonated 1 would be a WCA. Reactions of 1 with NOct 3 show that 1 forms weaker ion-pairs than classical WCAs, but stronger ion-pairs than carborane or borate anions. Though 1 forms stronger ion-pairs than these state-of-the-art WCAs, 1 reacts with alkylsilanes to form silylium type surface species. To the best of our knowledge, this is the first example of a silylium supported on derivatized silica. 

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4. The influence of crystal thickness and interlayer interactions on the properties of heavy ion irradiated MoS 2

   https://doi.org/10.1088/2053-1583/ab817b  

   Isherwood, Liam H. ; Hennighausen, Zachariah ; Son, Seok-Kyun ; Spencer, Ben F. ; Wady, Paul T. ; Shubeita, Samir M. ; Kar, Swastik ; Casiraghi, Cinzia ; Baidak, Aliaksandr ( May 2020 , 2D Materials)

   Ion irradiation is a versatile tool to introduce controlled defects into two-dimensional (2D) MoS₂on account of its unique spatial resolution and plethora of ion types and energies available. In order to fully realise the potential of this technique, a holistic understanding of ion-induced defect production in 2D MoS₂crystals of different thicknesses is mandatory. X-ray photoelectron spectroscopy, electron diffraction and Raman spectroscopy show that thinner MoS₂crystals are more susceptible to radiation damage caused by 225 keV Xe⁺ions. However, the rate of defect production in quadrilayer and bulk crystals is not significantly different under our experimental conditions. The rate at which S atoms are sputtered as a function of radiation exposure is considerably higher for monolayer MoS₂, compared to bulk crystals, leading to MoO₃formation. P-doping of MoS₂is observed and attributed to the acceptor states introduced by vacancies and charge transfer interactions with adsorbed species. Moreover, the out-of-plane vibrational properties of irradiated MoS₂crystals are shown to be strongly thickness-dependent: in mono- and bilayer MoS₂, the confinement of phonons by defects results in a blueshift of the$A_{1g}$mode. Whereas, a redshift is observed in bulk crystals due to attenuation of the effective restoring forces acting on S atoms caused by vacancies in adjacent MoS₂layers. Consequently, the$A_{1g}$frequency of tri- and quadrilayer crystals is statistically invariant on account oft competition between phonon confinement effects and interlayer interactions. The$A_{1g}$linewidth is observed to decrease in bi- and trilayer crystals after low dose irradiation and is attributed to layer decoupling. This work shows that there is a complex interplay between defect production, crystal thickness and interlayer interactions in MoS₂. Our results demonstrate that ion irradiation is an effective tool to modulate the electronic, vibrational and structural properties of MoS₂, which may prove beneficial for practical applications.

    

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5. Localized and delocalized bound states of the main isotopologue 48 O 3 and of 18 O-enriched 50 O 3 isotopomers of the ozone molecule near the dissociation threshold

   https://doi.org/10.1039/D0CP02177F  

   Kokoouline, Viatcheslav ; Lapierre, David ; Alijah, Alexander ; Tyuterev, Vladimir ( January 2020 , Physical Chemistry Chemical Physics)

   Knowledge of highly excited rovibrational states of ozone isotopologues is of key importance for modelling the dynamics of exchange reactions, for understanding longstanding problems related to isotopic anomalies of the ozone formation, and for analyses of extra-sensitive laser spectral experiments currently in progress. This work is devoted to new theoretical study of high-energy states for the main isotopologue 48 O 3 = 16 O 16 O 16 O and for the family of 18 O-enriched isotopomers 50 O 3 = { 16 O 16 O 18 O, 16 O 18 O 16 O, 18 O 16 O 16 O} of the ozone molecule considered using a full-symmetry approach. Energies and wave functions of bound states near the dissociation threshold are computed in hyperspherical coordinates accounting for the permutation symmetry of three identical nuclei in 48 O 3 and of two identical nuclei in 50 O 3 , using the most accurate potential energy surface available now. The obtained vibrational band centers agree with observed ones with the root-mean-squares deviation of about 1 cm −1 , making the results appropriate for assignments and analyses of future experimental spectra. The levels delocalized between the three potential wells of ozone isomers are computed and analyzed. The states situated deep in the three (for 48 O 3 ) or two (for 50 O 3 ) equivalent potential wells have similar energies with negligible splitting. However, the states situated just below the potential barriers separating the wells, are split due to the tunneling between the wells resulting in the splitting of rovibrational sub-bands. We evaluate the amplitudes of the corresponding effects and consider possible perturbations in vibration–rotation bands due to interactions between three potential wells. Theoretical predictions for the splitting of observable band centers are provided for the first time. 

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