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1. Medium‐Entropy Engineering of Magnetism in Layered Antiferromagnet Cu _x Ni _{2(1‐ x )} Cr _x P ₂ S ₆

   https://doi.org/10.1002/adfm.202418722  

   Upreti, Dinesh; Basnet, Rabindra; Sharma, M M; Chhetri, Santosh Karki; Acharya, Gokul; Nabi, Md_Rafique Un; Sakon, Josh; Benamara, Mourad; Mortazavi, Mansour; Hu, Jin (December 2024, Advanced Functional Materials)

   Abstract Antiferromagnetic van der Waals‐typeM₂P₂X₆compounds provide a versatile material platform for studying 2D magnetism and relevant phenomena. Establishing ferromagnetism in 2D materials is technologically valuable. Though magnetism is generally tunable via a chemical way, it is challenging to induce ferromagnetism with isovalent chalcogen and bimetallic substitutions inM₂P₂X₆. Here, we report co‐substitution of Cu¹⁺and Cr³⁺for Ni²⁺in Ni₂P₂S₆, creating Cu_xNi_2(1‐x)Cr_xP₂S₆medium‐entropy alloys spanning a full substitution range (x= 0 to 1). Such substitution strategy leads to a unique evolution in crystal structure and magnetic phases that are distinct from traditional isovalent bimetallic doping, with Cu and Cr co‐substitution enhancing ferromagnetic correlations and generating a weak ferromagnetic phase in intermediate compositions. This aliovalent substitution strategy offers a universal approach for tuning layered magnetism in antiferromagnetic systems, which along with the potential for light‐matter interaction and high‐temperature ferroelectricity, can enable multifunctional device applications. 

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2. Pattern of covalent and non‐covalent interactions within the pentaiodide anion in the structure of (3‐HOC ₅ H ₉ NH ₂ )I ₅

   https://doi.org/10.1002/zaac.202200039  

   Shestimerova, Tatiana A.; Bykov, Andrey V.; Kuznetsov, Alexey N.; Grishko, Alexey Y.; Wei, Zheng; Dikarev, Evgeny V.; Shevelkov, Andrei V. (March 2022, Zeitschrift für anorganische und allgemeine Chemie)

   Abstract 3‐Hydroxypiperidinium pentaiodide was synthesized by a facile reaction in concentrated aqueous HI. Its crystal structure comprises 3‐hydroxypiperidinium cations and pentaiodide anions, the latter having geometry ofcis‐shaped chains composed of I₂and I₃⁻building units. The analysis of interatomic distances, Raman spectroscopy data, and results of DFT calculations, including non‐covalent interaction analysis, showed that the title compound exhibits a complex pattern of covalent and non‐covalent interactions. Those include I−I covalent bonds and I⋅⋅⋅I halogen bonds within the I₅⁻anion as well as (N)H⋅⋅⋅I and (O)H⋅⋅⋅I hydrogen bonds and even weaker (C)H⋅⋅⋅I van‐der‐Waals interactions between the cations and anions. 

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3. Catalytic effect of DMSO in metal‐catalyzed radical polymerization mediated by disproportionation facilitates living and immortal radical polymerizations

   https://doi.org/10.1002/pol.20220632  

   Maurya, Devendra S.; Adamson, Jasper; Bensabeh, Nabil; Lligadas, Gerard; Percec, Virgil (February 2023, Journal of Polymer Science)

   Abstract DMSO, an interesting solvent for copper‐catalyzed living radical polymerization (LRP) mediated by disproportionation, does not exhibit the greatest disproportionation of Cu(I)X into Cu(0) and Cu(II)X₂. Under suitable conditions, DMSO provides 100% conversion and absence of termination, facilitating the development of complex‐architecture methodologies by living and immortal polymerizations. The mechanism yielding this level of precision is being investigated. Here we compare Cu(0)‐wire‐catalyzed LRP of methyl acrylate mediated by disproportionating ligands tris(2‐dimethylaminoethyl)amine, Me₆‐TREN, tris(2‐aminoethyl)amine, TREN, and Me₆‐TREN/TREN = 1/1 in presence of eight disproportionating solvents, some more efficient than DMSO in disproportionation. Unexpectedly, we observed that all solvents increased the rate of polymerization when monomer concentration decreased. This reversed trend from that of conventional LRPs demonstrates catalytic effect for disproportionating solvents. Above a certain concentration, the classic concentration‐rate dependence was observed. The external order of reaction of the apparent rate constant of propagation,k_p^appon solvent concentration demonstrated the highest order of reaction for the least disproportionating DMSO. Of all solvents investigated, DMSO has the highest ability to stabilize Cu(0) nanoparticles and therefore, yields the highest activity of Cu(0) nanoparticles rather than their greatest concentration. The implications of the catalytic effect of solvent in this and other reactions were discussed. 

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4. Redox‐Neutral S ‐nitrosation Mediated by a Dicopper Center

   https://doi.org/10.1002/anie.202102589  

   Tao, Wenjie; Moore, Curtis E.; Zhang, Shiyu (June 2021, Angewandte Chemie International Edition)

   Abstract A redox‐neutralS‐nitrosation of thiol has been achieved at a dicopper(I,I) center. Treatment of dicopper (I,I) complex with excess NO^.and thiol generates a dicopper (I,I) di‐S‐nitrosothiol complex [Cu^ICu^I(RSNO)₂]²⁺or dicopper (I,I) mono‐S‐nitrosothiol complex [Cu^ICu^I(RSNO)]²⁺, which readily release RSNO in 88–94 % yield. TheS‐nitrosation proceeds by a mixed‐valence [Cu^IICu^III(μ‐O)(μ‐NO)]²⁺species, which deprotonates RS‐H at the basic μ‐O site and nitrosates RS⁻at the μ‐NO site. The [Cu^IICu^III(μ‐O)(μ‐NO)]²⁺complex is also competent forO‐nitrosation of MeOH. A rare [Cu^IICu^II(μ‐NO)(OMe)]²⁺intermediate was isolated and fully characterized, suggesting theS‐nitrosation may proceed through the intermediary of analogous [Cu^IICu^II(μ‐NO)(SR)]²⁺species. This redox‐ and proton‐neutralS‐nitrosation process is the first functional model of ceruloplasmin in mediatingS‐nitrosation of external thiols, with implications for biological copper sites in the interconversion of NO^./RSNO. 

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5. Mosaic Cu ^I −Cu ^II −In ^III 2D Perovskites: Pressure‐Dependence of the Intervalence Charge Transfer and a Mechanochemical Alloying Method

   https://doi.org/10.1002/anie.202300957  

   Li, Jiayi; Matheu, Roc; Ke, Feng; Liu, Zhenxian; Lin, Yu; Karunadasa, Hemamala I. (April 2023, Angewandte Chemie International Edition)

   Abstract The perovskite (BA)₄[Cu^II(Cu^IIn^III)_0.5]Cl₈(1_BA; BA⁺=butylammonium) allows us to study the high‐pressure structural, optical, and transport properties of a mixed‐valence 2D perovskite. Compressing1_BAreduces the onset energy of Cu^I/IIintervalence charge transfer from 1.2 eV at ambient pressure to 0.2 eV at 21 GPa. The electronic conductivity of1_BAincreases by 4 orders of magnitude upon compression to 20 GPa, when the activation energy for conduction decreases to 0.16 eV. In contrast, Cu^IIperovskites achieve similar conductivity at ≈50 GPa. The solution‐state synthesis of these perovskites is complicated, with more undesirable side products likely from the precursor mixtures containing three different metal ions. To circumvent this problem, we demonstrate an efficient mechanochemical synthesis to expand this family of halide perovskites with complex composition by simply pulverizing together powders of 2D Cu^IIsingle perovskites and Cu^IIn^IIIdouble perovskites. 

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