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1. Inclusive quarkonium production in pp collisions at $$\sqrt{s}$$ = 5.02 TeV

   https://doi.org/10.1140/epjc/s10052-022-10896-8  

   Acharya, S.; Adamová, D.; Adler, A.; Adolfsson, J.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; et al (January 2023, The European Physical Journal C)

   Abstract This article reports on the inclusive production cross section of several quarkonium states, $$\textrm{J}/\psi $$ J / ψ , $$\psi \mathrm{(2S)}$$ ψ ( 2 S ) , $$\Upsilon \mathrm (1S)$$ Υ ( 1 S ) , $$\Upsilon \mathrm{(2S)}$$ Υ ( 2 S ) , and $$\Upsilon \mathrm{(3S)}$$ Υ ( 3 S ) , measured with the ALICE detector at the LHC, in pp collisions at $$\sqrt{s} = 5.02$$ s = 5.02  TeV. The analysis is performed in the dimuon decay channel at forward rapidity ( $$2.5< y < 4$$ 2.5 < y < 4 ). The integrated cross sections and transverse-momentum ( $$p_{\textrm{T}}$$ p T ) and rapidity ( $$y$$ y ) differential cross sections for $$\textrm{J}/\psi $$ J / ψ , $$\psi \mathrm{(2S)}$$ ψ ( 2 S ) , $$\Upsilon \mathrm (1S)$$ Υ ( 1 S ) , and the $$\psi \mathrm{(2S)}$$ ψ ( 2 S ) -to- $$\textrm{J}/\psi $$ J / ψ cross section ratios are presented. The integrated cross sections, assuming unpolarized quarkonia, are: $$\sigma _{\textrm{J}/\psi }$$ σ J / ψ  ( $$p_{\textrm{T}} <20$$ p T < 20  GeV/c) = 5.88 ± 0.03 ± 0.34 $$ ~\mu $$ μ b, $$\sigma _{\psi \mathrm{(2S)}}$$ σ ψ ( 2 S )  ( $$p_{\textrm{T}} <12$$ p T < 12  GeV/c) = 0.87 ± 0.06 ± 0.10 $$~\mu $$ μ b, $$\sigma _{\Upsilon \mathrm (1S)}$$ σ Υ ( 1 S )  ( $$p_{\textrm{T}} <15$$ p T < 15  GeV/c) = 45.5 ± 3.9 ± 3.5 nb, $$\sigma _{\Upsilon \mathrm{(2S)}}$$ σ Υ ( 2 S )  ( $$p_{\textrm{T}} <15$$ p T < 15  GeV/c) = 22.4 ± 3.2 ± 2.7 nb, and $$\sigma _{\Upsilon \mathrm{(3S)}}$$ σ Υ ( 3 S )  ( $$p_{\textrm{T}} <15$$ p T < 15  GeV/c) = 4.9 ± 2.2 ± 1.0 nb, where the first (second) uncertainty is the statistical (systematic) one. For the first time, the cross sections of the three $$\Upsilon $$ Υ states, as well as the $$\psi \mathrm{(2S)}$$ ψ ( 2 S ) one as a function of $$p_{\textrm{T}}$$ p T and $$y$$ y , are measured at $$\sqrt{s} = 5.02$$ s = 5.02  TeV at forward rapidity. These measurements also significantly extend the $$\textrm{J}/\psi $$ J / ψ $$p_{\textrm{T}}$$ p T reach and supersede previously published results. A comparison with ALICE measurements in pp collisions at $$\sqrt{s} = 2.76$$ s = 2.76 , 7, 8, and 13 TeV is presented and the energy dependence of quarkonium production cross sections is discussed. Finally, the results are compared with the predictions from several production models. 

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2. Electron and Spin Delocalization in [Co ₆ Se ₈ (PEt ₃ ) ₆ ] ^0/+1 Superatoms

   https://doi.org/10.1002/cphc.202300064  

   Xu, Yunyao; Chen, Jia; Aydt, Alexander P.; Zhang, Lichirui; Sergeyev, Ivan; Keeler, Eric G.; Choi, Bonnie; He, Shoushou; Reichman, David R.; Friesner, Richard A.; et al (January 2024, ChemPhysChem)

   ChemPhysChem (Ed.)

   Abstract Molecular clusters can function as nanoscale atoms/superatoms, assembling into superatomic solids, a new class of solid‐state materials with designable properties through modifications on superatoms. To explore possibilities on diversifying building blocks, here we thoroughly studied one representative superatom, Co₆Se₈(PEt₃)₆. We probed its structural, electronic, and magnetic properties and revealed its detailed electronic structure as valence electrons delocalize over inorganic [Co₆Se₈] core while ligands function as an insulated shell.⁵⁹Co SSNMR measurements on the core and³¹P,¹³C on the ligands show that the neutral Co₆Se₈(PEt₃)₆is diamagnetic and symmetric, with all ligands magnetically equivalent. Quantum computations cross‐validate NMR results and reveal degenerate delocalized HOMO orbitals, indicating aromaticity. Ligand substitution keeps the inorganic core nearly intact. After losing one electron, the unpaired electron in [Co₆Se₈(PEt₃)₆]⁺¹is delocalized, causing paramagnetism and a delocalized electron spin. Notably, this feature of electron/spin delocalization over a large cluster is attractive for special single‐electron devices. 

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3. Understanding the Early Stages of Nickel Sulfide Nanocluster Growth: Isolation of Ni ₃ , Ni ₄ , Ni ₅ , and Ni ₈ Intermediates

   https://doi.org/10.1002/smll.202003133  

   Touchton, Alexander J.; Wu, Guang; Hayton, Trevor W. (September 2020, Small)

   Abstract Addition of sub‐stoichiometric quantities of PEt₃and diphenyl disulfide to a solution of [Ni(1,5‐cod)₂] generates a mixture of [Ni₃(SPh)₄(PEt₃)₃] (1), unreacted [Ni(1,5‐cod)₂], and [(1,5‐cod)Ni(PEt₃)₂], according to¹H and³¹P{¹H} NMR spectroscopic monitoring of the in situ reaction mixture. On standing, complex1converts into [Ni₄(S)(Ph)(SPh)₃(PEt₃)₃] (2), via formal addition of a “Ni(0)” equivalent, coupled with a CS oxidative addition step, which simultaneously generates the Ni‐bound phenyl ligand and the μ₃‐sulfide ligand. Upon gentle heating, complex2converts into a mixture of [Ni₅(S)₂(SPh)₂(PEt₃)₅] (3) and [Ni₈(S)₅(PEt₃)₇] (4), via further addition of “Ni(0)” equivalents, in combination with a series of C–S oxidative addition and CC reductive elimination steps, which serve to convert thiophenolate ligands into sulfide ligands and biphenyl. The presence of1–4in the reaction mixture is confirmed by their independent syntheses and subsequent spectroscopic characterization. Overall, this work provides an unprecedented level of detail of the early stages of Ni nanocluster growth and highlights the fundamental reaction steps (i.e., metal atom addition, CS oxidative addition, and CC reductive elimination) that are required to grow an individual cluster. 

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4. Catalytic Metallopolymers from [2Fe‐2S] Clusters: Artificial Metalloenzymes for Hydrogen Production

   https://doi.org/10.1002/ange.201813776  

   Karayilan, Metin; Brezinski, William P.; Clary, Kayla E.; Lichtenberger, Dennis L.; Glass, Richard S.; Pyun, Jeffrey (March 2019, Angewandte Chemie)

   Abstract Reviewed herein is the development of novel polymer‐supported [2Fe‐2S] catalyst systems for electrocatalytic and photocatalytic hydrogen evolution reactions. [FeFe] hydrogenases are the best known naturally occurring metalloenzymes for hydrogen generation, and small‐molecule, [2Fe‐2S]‐containing mimetics of the active site (H‐cluster) of these metalloenzymes have been synthesized for years. These small [2Fe‐2S] complexes have not yet reached the same capacity as that of enzymes for hydrogen production. Recently, modern polymer chemistry has been utilized to construct an outer coordination sphere around the [2Fe‐2S] clusters to provide site isolation, water solubility, and improved catalytic activity. In this review, the various macromolecular motifs and the catalytic properties of these polymer‐supported [2Fe‐2S] materials are surveyed. The most recent catalysts that incorporate a single [2Fe‐2S] complex, termed single‐site [2Fe‐2S] metallopolymers, exhibit superior activity for H₂production. 

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5. Reduced 2,2’‐Bipyridine Lanthanide Metallocenes Provide Access to Mono‐C ₅ Me ₅ and Polyazide Complexes

   https://doi.org/10.1002/ejic.202300732  

   Stennett, Cary_R; Ziller, Joseph_W; Evans, William_J (March 2024, European Journal of Inorganic Chemistry)

   Abstract Exploration of the reduction chemistry of the 2,2’‐bipyridine (bipy) lanthanide metallocene complexes Cp*₂LnCl(bipy) and Cp*₂Ln(bipy) (Cp* = C₅Me₅) resulted in the isolation of a series of complexes with unusual composition and structure including complexes with a single Cp* ligand, multiple azide ligands, and bipy ligands with close parallel orientations. These results not only reveal new structural types, but they also show the diverse chemistry displayed by this redox‐active platform. Treatment of Cp*₂NdCl(bipy) with excess KC₈resulted in the formation of the mono‐Cp* Nd(III) complex, [K(crypt)]₂[Cp*Nd(bipy)₂],1, as well as [K(crypt)][Cp*₂NdCl₂],2, and the previously reported [K(crypt)][Cp*₂Nd(bipy)]. A mono‐Cp* Lu(III) complex, Cp*Lu(bipy)₂,3, was also found in an attempt to make Cp*₂Lu(bipy) from LuCl₃, 2 equiv. of KCp*, bipy, and K/KI. Surprisingly, the (bipy)¹⁻ligands in neighboring molecules in the structure of3are oriented in a parallel fashion with intermolecular C⋅⋅⋅C distances of 3.289(4) Å, which are shorter than the sum of van der Waals radii of two carbon atoms, 3.4 Å. Another product with one Cp* ligand per lanthanide was isolated from the reaction of [K(crypt)][Cp*₂Eu(bipy)] with azobenzene, which afforded the dimeric Eu(II) complex, [K(crypt)]₂[Cp*Eu(THF)(PhNNPh)]₂,4. Attempts to make4from the reaction between Cp*₂Eu(THF)₂and a reduced azobenzene anion generated instead the mixed‐valent Eu(III)/Eu(II) complex, [K(crypt)][Cp*Eu(THF)(PhNNPh)]₂,5, which allows direct comparison with the bimetallic Eu(II) complex4. Mono‐Cp* complexes of Yb(III) are obtained from reactions of the Yb(II) complex, [K(crypt)][Cp*₂Yb(bipy)], with trimethylsilylazide, which afforded the tetra‐azido [K(crypt)]₂[Cp*Yb(N₃)₄],6, or the di‐azido complex [K(crypt)]₂[Cp*Yb(N₃)₂(bipy)],7 a, depending on the reaction stoichiometry. A mono‐Cp* Yb(III) complex is also isolated from reaction of [K(crypt)][Cp*₂Yb(bipy)] with elemental sulfur which forms the mixed polysulfido Yb(III) complex [K(crypt)]₂[Cp*Yb(S₄)(S₅)],8 a. In contrast to these reactions that form mono‐Cp* products, reduction of Cp*₂Yb(bipy) with 1 equiv. of KC₈in the presence of 18‐crown‐6 resulted in the complete loss of Cp* ligands and the formation of [K(18‐c‐6)(THF)][Yb(bipy)₄],9. The (bipy)¹⁻ligands of9are arranged in a parallel orientation, as observed in the structure of3, except in this case this interaction is intramolecular and involves pairs of ligands bound to the same Yb atom. Attempts to reduce further the Sm(II) (bipy)¹⁻complex, Cp*₂Sm(bipy) with 2 equiv. of KC₈in the presence of excess 18‐crown‐6 led to the isolation of a Sm(III) salt of (bipy)²⁻with an inverse sandwich Cp* counter‐cation and a co‐crystallized K(18‐c‐6)Cp* unit, [K₂(18‐c‐6)₂Cp*]₂[Cp*₂Sm(bipy)]₂ ⋅ [K(18‐c‐6)Cp*],10. 

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