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1. Electronic relaxation dynamics in [Au 25 (SR) 18 ] −1 (R = CH 3 , C 2 H 5 , C 3 H 7 , MPA, PET) thiolate-protected nanoclusters

   https://doi.org/10.1039/C9CP04039K  

   Senanayake, Ravithree D. ; Aikens, Christine M. ( March 2020 , Physical Chemistry Chemical Physics)

   null (Ed.)

   We investigate the excited electron dynamics in [Au 25 (SR) 18 ] −1 (R = CH 3 , C 2 H 5 , C 3 H 7 , MPA, PET) [MPA = mercaptopropanoic acid, PET = phenylethylthiol] nanoparticles to understand how different ligands affect the excited state dynamics in this system. The population dynamics of the core and higher excited states lying in the energy range 0.00–2.20 eV are studied using a surface hopping method with decoherence correction in a real-time DFT approach. All of the ligated clusters follow a similar trend in decay for the core states (S 1 –S 6 ). The observed time constants are on the picosecond time scale (2–19 ps), which agrees with the experimental time scale, and this study confirms that the time constants observed experimentally could originate from core-to-core transitions and not from core-to-semiring transitions. In the presence of higher excited states, R = H, CH 3 , C 2 H 5 , C 3 H 7 , and PET demonstrate similar relaxations trends whereas R = MPA shows slightly different relaxation of the core states due to a smaller gap between the LUMO+1 and LUMO+2 gap in its electronic structure. The S 1 (HOMO → LUMO) state gives the slowest decay in all ligated clusters, while S 7 has a relatively long decay. Furthermore, separate electron and hole relaxations were performed on the [Au 25 (SCH 3 ) 18 ] −1 nanocluster to understand how independent electron and hole relaxations contribute to the overall relaxation dynamics. 

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2. The reaction of alkyl hydropersulfides (RSSH, R = CH 3 and t Bu) with H 2 S in the gas phase and in aqueous solution

   https://doi.org/10.1039/C8CP05503C  

   Zhang, Linxing ; Zhang, Xinhao ; Wu, Yun-Dong ; Xie, Yaoming ; Fukuto, Jon M. ; Schaefer, Henry F. ( January 2019 , Physical Chemistry Chemical Physics)

   The RSSH + H 2 S → RSH + HSSH reaction has been suggested by numerous labs to be important in H 2 S-mediated biological processes. Seven different mechanisms for this reaction (R = CH 3 , as a model) have been studied using the DFT methods (M06-2X and ωB97X-D) with the Dunning aug-cc-pV(T+d)Z basis sets. The reaction of CH 3 SSH with gas phase H 2 S has a very high energy barrier (>45 kcal mol −1 ), consistent with the available experimental observations. A series of substitution reactions R 1 –S–S–H + − S–R 2 (R 1 = Me, t Bu, Ad, R 2 = H, S–Me, S– t Bu, S–Ad) have been studied. The regioselectivity is largely affected by the steric bulkiness of R 1 , but is much less sensitive to R 2 . Thus, when R 1 is Me, all − S–R 2 favorably attack the internal S atom, leading to R 1 –S–S–R 2 . While for R 1 = t Bu, Ad, all − S–R 2 significantly prefer to attack the external S atom to form − S–S–R 2 . These results are in good agreement with the experimental observations. 

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3. The β‐Agostic Structure in (C 5 Me 5 ) 2 Sc(CH 2 CH 3 ): Solid‐State NMR Studies of (C 5 Me 5 ) 2 Sc−R (R=Me, Ph, Et)

   https://doi.org/10.1002/anie.201805738  

   Culver, Damien B. ; Huynh, Winn ; Tafazolian, Hosein ; Ong, Ta‐Chung ; Conley, Matthew P. ( July 2018 , Angewandte Chemie International Edition)

   Multinuclear solid‐state NMR studies of Cp*₂Sc−R (Cp*=pentamethylcyclopentadienyl; R=Me, Ph, Et) and DFT calculations show that the Sc−Et complex contains a β‐CH agostic interaction. The static central transition⁴⁵Sc NMR spectra show that the quadrupolar coupling constants (C_q) follow the trend of Ph≈Me>Et, indicating that the Sc−R bond is different in Cp*₂Sc−Et compared to the methyl and phenyl complexes. Analysis of the chemical shift tensor (CST) shows that the deshielding experienced by Cβ in Sc−CH₂CH₃is related to coupling between the filled σ_C‐Corbital and the vacantorbital.

    

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4. The β‐Agostic Structure in (C 5 Me 5 ) 2 Sc(CH 2 CH 3 ): Solid‐State NMR Studies of (C 5 Me 5 ) 2 Sc−R (R=Me, Ph, Et)

   https://doi.org/10.1002/ange.201805738  

   Culver, Damien B. ; Huynh, Winn ; Tafazolian, Hosein ; Ong, Ta‐Chung ; Conley, Matthew P. ( July 2018 , Angewandte Chemie)

   Multinuclear solid‐state NMR studies of Cp*₂Sc−R (Cp*=pentamethylcyclopentadienyl; R=Me, Ph, Et) and DFT calculations show that the Sc−Et complex contains a β‐CH agostic interaction. The static central transition⁴⁵Sc NMR spectra show that the quadrupolar coupling constants (C_q) follow the trend of Ph≈Me>Et, indicating that the Sc−R bond is different in Cp*₂Sc−Et compared to the methyl and phenyl complexes. Analysis of the chemical shift tensor (CST) shows that the deshielding experienced by Cβ in Sc−CH₂CH₃is related to coupling between the filled σ_C‐Corbital and the vacantorbital.

    

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5. Solid-State End-On to Side-On Isomerization of (N═N) 2– in {[(R 2 N) 3 Nd] 2 N 2 } 2– (R = SiMe 3 ) Connects In Situ Ln III (NR 2 ) 3 /K and Isolated [Ln II (NR 2 ) 3 ] 1– Dinitrogen Reduction

   https://doi.org/10.1021/jacs.2c06716  

   Chung, Amanda B. ; Rappoport, Dmitrij ; Ziller, Joseph W. ; Cramer, Roger E. ; Furche, Filipp ; Evans, William J. ( September 2022 , Journal of the American Chemical Society)