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1. Crystal structure of (1,4,7,10,13,16-hexaoxacyclooctadecane-κ ⁶ O )potassium-μ-oxalato-triphenylstannate(IV), the first reported 18-crown-6-stabilized potassium salt of triphenyloxalatostannate

   https://doi.org/10.1107/S2056989024007758  

   Song, Xueqing; Li, William; Torres, Yolanda; Greaves, Tazena (September 2024, Acta Crystallographica Section E Crystallographic Communications)

   The title complex, (1,4,7,10,13,16-hexaoxacyclooctadecane-1κ⁶O)(μ-oxalato-1κ²O¹,O²:2κ²O^1′,O^2′)triphenyl-2κ³C-potassium(I)tin(IV), [KSn(C₆H₅)₃(C₂O₄)(C₁₂H₂₄O₆)] or K[18-Crown-6][(C₆H₅)₃SnO₄C₂], was synthesized. The complex consists of a potassium cation coordinated to the six oxygen atoms of a crown ether molecule and the two oxygen atoms of the oxalatotriphenylstannate anion. It crystallizes in the monoclinic crystal system within the space groupP2₁. The tin atom is coordinated by one chelating oxalate ligand and three phenyl groups, forming acis-trigonal–bipyramidal geometry around the tin atom. The cations and anions form ion pairs, linked through carbonyl coordination to the potassium atoms. The crystal structure features C—H...O hydrogen bonds between the oxygen atoms of the oxalate group and the hydrogen atoms of the phenyl groups, resulting in an infinite chain structure extending alonga-axis direction. The primary inter-chain interactions are van der Waals forces. 

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2. Scalable ω‐Substituted α‐Olefins via Living Chain Transfer Telomerization: A Platform for Next Generation Polyolefins

   https://doi.org/10.1002/anie.6963058  

   Logue, Lauren G; Burrows, Cole M; Wedekind, Vince J; Kim, Hyunku C; Sita, Lawrence R (August 2026, Angewandte Chemie International Edition)

   ABSTRACT Isomerically pure, ω‐substituted α‐olefins of general structure, X‐(CH₂)_m(CH₂CH₂)_n‐1CH = CH₂(m= 0 or 1; X = alkyl or aryl) (3), have been produced in practical and scalable quantities as narrow Poisson molar mass distributions of separablen‐mers (e.g.n= 1 – 10) through a one‐pot, two‐step process involving: living ternary chain transfer telomerization of tris(ω‐substituted alkyl)aluminum, [X‐(CH₂)_mCH₂CH₂]₃Al (1), with ethene and a small amount of diethylzinc as a chain transfer mediator, using an in situ generated ion pair initiator derived from the cyclopentadienyl, amidinate (CPAM) Hf pre‐initiator, (η⁵‐C₅Me₅)[κ²‐(N,N’)‐N(Et)C(Me)N(Et)]HfMe₂(2) and the borate co‐initiator, [PhNHMe₂][B(C₆F₅)₄] (B), followed by catalytic displacement of the trialkylaluminum intermediate using bis(1,5‐cyclooctadiene)Ni(0) as the pre‐catalyst. Results are further presented for production of several families of “next generation” polyolefins that are obtained through CPAM Zr‐ and Hf‐mediated stereoselective (enantioselective) living coordination polymerization of different derivatives of3and including copolymerization with a variety of linear and branched α‐olefins and 1,5‐hexadiene. 

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3. Stabilization of the Benzene Radical Trianion in an Inverse‐Sandwich Yttrium Complex

   https://doi.org/10.1002/anie.202521849  

   Mao, Weiqing; Deshapriya, Saroshan; Yao, Shenglai; Lorent, Christian; Driess, Matthias; Demir, Selvan (December 2025, Angewandte Chemie International Edition)

   Abstract Herein, the first report on the isolated and unambiguously proven benzene radical trianion is presented. This unprecedented radical oxidation state of benzene is stabilized through two trivalent rare earth (RE) metal cations each supported by a bis(guanidinate) scaffold. Specifically, the one‐electron chemical reduction of the neutral inverse‐sandwich yttrium complex [[{(Me₃Si)₂NC(NⁱPr)₂}₂Y]₂(μ–ƞ⁶:ƞ⁶–C₆H₆)]1, containing a benzene dianion, with potassium graphite (KC₈) in the presence of [2.2.2]‐cryptand yielded the title complex [K([2.2.2]‐cryptand)][[{(Me₃Si)₂NC(NⁱPr)₂}₂Y]₂(μ–ƞ⁶:ƞ⁶–C₆H₆^•)]2, featuring a benzene radical trianion. Analyses through single‐crystal X‐ray diffraction, EPR and UV–vis spectroscopy, elucidated its molecular structure and revealed strong [Y^III–(C₆H₆)^3–•–Y^III] metal–radical interactions. Although the Y centers remain in the +3 oxidation state, the spin density of the unpaired electron resides primarily on the benzene trianion moiety and extends toward the Y^IIIions. Density functional theory (DFT) calculations on2corroborate this assignment and further suggest weak aromaticity for the benzene radical trianion. 

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4. Semiquinone radical-bridged M ₂ (M = Fe, Co, Ni) complexes with strong magnetic exchange giving rise to slow magnetic relaxation

   https://doi.org/10.1039/d0sc03078c  

   Chakarawet, Khetpakorn; Harris, T. David; Long, Jeffrey R. (August 2020, Chemical Science)

   null (Ed.)

   The use of radical bridging ligands to facilitate strong magnetic exchange between paramagnetic metal centers represents a key step toward the realization of single-molecule magnets with high operating temperatures. Moreover, bridging ligands that allow the incorporation of high-anisotropy metal ions are particularly advantageous. Toward these ends, we report the synthesis and detailed characterization of the dinuclear hydroquinone-bridged complexes [(Me 6 tren) 2 MII2(C 6 H 4 O 2 2− )] 2+ (Me 6 tren = tris(2-dimethylaminoethyl)amine; M = Fe, Co, Ni) and their one-electron-oxidized, semiquinone-bridged analogues [(Me 6 tren) 2 MII2(C 6 H 4 O 2 − ˙)] 3+ . Single-crystal X-ray diffraction shows that the Me 6 tren ligand restrains the metal centers in a trigonal bipyramidal geometry, and coordination of the bridging hydro- or semiquinone ligand results in a parallel alignment of the three-fold axes. We quantify the p -benzosemiquinone–transition metal magnetic exchange coupling for the first time and find that the nickel( ii ) complex exhibits a substantial J < −600 cm −1 , resulting in a well-isolated S = 3/2 ground state even as high as 300 K. The iron and cobalt complexes feature metal–semiquinone exchange constants of J = −144(1) and −252(2) cm −1 , respectively, which are substantially larger in magnitude than those reported for related bis(bidentate) semiquinoid complexes. Finally, the semiquinone-bridged cobalt and nickel complexes exhibit field-induced slow magnetic relaxation, with relaxation barriers of U eff = 22 and 46 cm −1 , respectively. Remarkably, the Orbach relaxation observed for the Ni complex is in stark contrast to the fast processes that dominate relaxation in related mononuclear Ni II complexes, thus demonstrating that strong magnetic coupling can engender slow magnetic relaxation. 

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5. Tribochemically Controlled Atom Transfer Radical Polymerization Enabled by Contact Electrification

   https://doi.org/10.1002/anie.202309440  

   Wang, Chen; Zhao, Ruoqing; Fan, Wenru; Li, Lei; Feng, Haoyang; Li, Zexuan; Yan, Ci; Shao, Xiaoyang; Matyjaszewski, Krzysztof; Wang, Zhenhua (September 2023, Angewandte Chemie International Edition)

   Abstract Traditional mechanochemically controlled reversible‐deactivation radical polymerization (RDRP) utilizes ultrasound or ball milling to regenerate activators, which induce side reactions because of the high‐energy and high‐frequency stimuli. Here, we propose a facile approach for tribochemically controlled atom transfer radical polymerization (tribo‐ATRP) that relies on contact‐electro‐catalysis (CEC) between titanium oxide (TiO₂) particles and CuBr₂/tris(2‐pyridylmethylamine (TPMA), without any high‐energy input. Under the friction induced by stirring, the TiO₂particles are electrified, continuously reducing CuBr₂/TPMA into CuBr/TPMA, thereby conversing alkyl halides into active radicals to start ATRP. In addition, the effect of friction on the reaction was elucidated by theoretical simulation. The results indicated that increasing the frequency could reduce the energy barrier for the electron transfer from TiO₂particles to CuBr₂/TPMA. In this study, the design of tribo‐ATRP was successfully achieved, enabling CEC (ca. 10 Hz) access to a variety of polymers with predetermined molecular weights, low dispersity, and high chain‐end fidelity. 

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