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1. Werner Complexes with ω‐Dimethylaminoalkyl Substituted Ethylenediamine Ligands: Bifunctional Hydrogen‐Bond‐Donor Catalysts for Highly Enantioselective Michael Additions

   https://doi.org/10.1002/anie.201511314  

   Ghosh, Subrata K; Ganzmann, Carola; Bhuvanesh, Nattamai; Gladysz, John A (March 2016, Angewandte Chemie International Edition)

   Abstract The racemic carbonate complex [Co(en)₂O₂CO]⁺Cl⁻(en=1,2‐ethylenediamine) and (S)‐[H₃NCH((CH₂)_nNHMe₂)CH₂NH₃]³⁺3 Cl⁻(n=1–4) react (water, charcoal, 100 °C) to give [Co(en)₂((S)‐H₂NCH((CH₂)_nNHMe₂)CH₂NH₂)]⁴⁺4 Cl⁻(3 a–d H⁴⁺4 Cl⁻) as a mixture of Λ/Δ diastereomers that separate on chiral‐phase Sephadex columns. These are treated with NaOH/Na⁺BAr_f⁻(BAr_f=B(3,5‐C₆H₃(CF₃)₂)₄) to give lipophilic Λ‐ and Δ‐3 a–d³⁺3 BAr_f⁻, which are screened as catalysts (10 mol %) for additions of dialkyl malonates to nitroalkenes. Optimal results are obtained with Λ‐3 c³⁺3 BAr_f⁻(CH₂Cl₂, −35 °C; 98–82 % yields and 99–93 %eefor six β‐arylnitroethenes). The monofunctional catalysts Λ‐ and Δ‐[Co(en)₃]³⁺3 BAr_f⁻give enantioselectivities of <10 %eewith equal loadings of Et₃N. The crystal structure of Δ‐3 a H⁴⁺4 Cl⁻provides a starting point for speculation regarding transition‐state assemblies. 

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2. Syntheses and crystal structures of three triphenylsulfonium salts of manganese(II), iron(III) and cobalt(II)

   https://doi.org/10.1107/S2056989025006668  

   Callaway, Waylan; Elterman, Matthew; Krasilnikov, Nikita; Roberts, Gavin; Rutan, Davis; Spencer, Ty; Padgett, Clifford W; Lynch, Will E (August 2025, Acta Crystallographica Section E Crystallographic Communications)

   Bis(triphenylsulfonium) tetrachloridomanganate(II), (C₁₈H₁₅S)₂[MnCl₄] (I), triphenylsulfonium tetrachloridoferrate(III), (C₁₈H₁₅S)[FeCl₄] (II), and bis(triphenylsulfonium) tetrachloridocobaltate(II), (C₁₈H₁₅S)₂[CoCl₄] (III), crystallize in the monoclinic space groupsP2₁/n[(I) and (III)] andP2₁/c[(II)]. Compounds (I) and (III) each contain two crystallographically independent triphenylsulfonium (TPS⁺) cations in the asymmetric unit, whereas (II) has one. In all three compounds, the sulfonium centers adopt distorted trigonal–pyramidal geometries, with S—C bond lengths falling roughly in the 1.78–1.79 Å range and C—S—C angles observed at about 101 to 106°. The [MCl₄]ⁿ⁻anions (M= Mn²⁺, Fe³⁺, Co²⁺;n= 2,1,2) adopt slightly distorted tetrahedral geometries, withM—Cl bond lengths in the 2.19–2.38 Å range and Cl—M—Cl angles of approximately 104–113°. Hirshfeld surface analyses shows that H...H and H...C contacts dominate the TPS⁺cation environments, whereas H...Cl and shortM—S interactions link each [MCl₄]ⁿ⁻anion to the surrounding cations. In (I) and (III), inversion-centered π–π stacking further consolidates the crystal packing, while in (II) no π–π interactions are observed. 

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3. Syntheses, structures, and stabilities of aliphatic and aromatic fluorous iodine(I) and iodine(III) compounds: the role of iodine Lewis basicity

   https://doi.org/10.3762/bjoc.13.246  

   Mukherjee, Tathagata; Biswas, Soumik; Ehnbom, Andreas; Ghosh, Subrata K; El-Zoghbi, Ibrahim; Bhuvanesh, Nattamai; Bazzi, Hassan S; Gladysz, John A (January 2017, Beilstein Journal of Organic Chemistry)

   The title molecules are sought in connection with various synthetic applications. The aliphatic fluorous alcohols R_fnCH₂OH (R_fn= CF₃(CF₂)_n–1;n= 11, 13, 15) are converted to the triflates R_fnCH₂OTf (Tf₂O, pyridine; 22–61%) and then to R_fnCH₂I (NaI, acetone; 58–69%). Subsequent reactions with NaOCl/HCl give iodine(III) dichlorides R_fnCH₂ICl₂(n= 11, 13; 33–81%), which slowly evolve Cl₂. The ethereal fluorous alcohols CF₃CF₂CF₂O(CF(CF₃)CF₂O)_xCF(CF₃)CH₂OH (x= 2–5) are similarly converted to triflates and then to iodides, but efforts to generate the corresponding dichlorides fail. Substrates lacking a methylene group, R_fnI, are also inert, but additions of TMSCl to bis(trifluoroacetates) R_fnI(OCOCF₃)₂appear to generate R_fnICl₂, which rapidly evolve Cl₂. The aromatic fluorous iodides 1,3-R_f6C₆H₄I, 1,4-R_f6C₆H₄I, and 1,3-R_f10C₆H₄I are prepared from the corresponding diiodides, copper, and R_fnI (110–130 °C, 50–60%), and afford quite stable R_fnC₆H₄ICl₂species upon reaction with NaOCl/HCl (80–89%). Iodinations of 1,3-(R_f6)₂C₆H₄and 1,3-(R_f8CH₂CH₂)₂C₆H₄(NIS or I₂/H₅IO₆) give 1,3,5-(R_f6)₂C₆H₃I and 1,2,4-(R_f8CH₂CH₂)₂C₆H₃I (77–93%). The former, the crystal structure of which is determined, reacts with Cl₂to give a 75:25 ArICl₂/ArI mixture, but partial Cl₂evolution occurs upon work-up. The latter gives the easily isolated dichloride 1,2,4-(R_f8CH₂CH₂)₂C₆H₃ICl₂(89%). The relative thermodynamic ease of dichlorination of these and other iodine(I) compounds is probed by DFT calculations. 

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4. Syntheses and crystal structures of three triphenylsulfonium halometallate salts of zinc, cadmium and mercury

   https://doi.org/10.1107/S2056989025002245  

   Artis, Rylan; Heyward, Elizabeth; Reyes, Naomi; Van_Ostenbridge, Kaitlyn; Lynch, Will E; Padgett, Clifford W (April 2025, Acta Crystallographica Section E Crystallographic Communications)

   Bis(triphenylsulfonium) tetrachloridozinc(II), (C₁₈H₁₅S)₂[ZnCl₄] (I), bis(triphenylsulfonium) tetrachloridocadmium(II), (C₁₈H₁₅S)₂[CdCl₄] (II), and bis(triphenylsulfonium) tetrachloridomercury(II) methanol monosolvate, (C₁₈H₁₅S)₂[HgCl₄]·CH₃OH (III), each crystallize in the monoclinic space groupP2₁/n. In all three structures, there are two crystallographically independent triphenylsulfonium (TPS) cations per asymmetric unit, each adopting a distorted trigonal–pyramidal geometry about the S atom (S—C bond lengths in the 1.77–1.80 Å range and C—S—C angles of 100–107°). The [MCl₄]^2–anions (M= Zn²⁺, Cd²⁺, Hg²⁺) are tetrahedral; their M—Cl bond lengths systematically increase from Zn²⁺to Hg²⁺, consistent with the larger ionic radius of the heavier metal. Hirshfeld surface analyses show that H...H and H...C contacts dominate the TPS cation environments, whereas H...Cl and S...Minteractions anchor each [MCl₄]^2–anion to two surrounding TPS cations. Weak C—H...Cl hydrogen bonds, as well as inversion-centered π–π stacking, generate layers in (I) and (II) and dimeric [(TPS)₂–HgCl₄]₂assemblies in (III). 

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5. Structural insights into supramolecular interactions in isostructural salts of 2,4,6-triaminopyrimidinium with various heterocyclic carboxylates

   https://doi.org/10.1107/S2053229624008787  

   Mohana, Marimuthu; Gomathi, Sundaramoorthy; Thomas_Muthiah, Packianathan; Butcher, Ray J (November 2024, Acta Crystallographica Section C Structural Chemistry)

   2,4,6-Triaminopyrimidine is an interesting and challenging molecule due to the presence of multiple hydrogen-bond donors and acceptors. Its noncovalent interactions with a variety of carboxylic acids provide several supramolecular aggregates with frequently occurring molecular synthons. The present work focuses on the supramolecular interactions of 2,4,6-triaminopyrimidinium 3-(indol-3-yl)propionate–3-(indol-3-yl)propionic acid (1/1), C₄H₈N₅⁺·C₁₁H₁₀NO₂⁻·C₁₁H₁₁NO₂, (I), 2,4,6-triaminopyrimidinium 2-(indol-3-yl)acetate, C₄H₈N₅⁺·C₁₀H₈NO₂⁻, (II), 2,4,6-triaminopyrimidinium 5-bromothiophene-2-carboxylate, C₄H₈N₅⁺·C₅H₂BrO₂S⁻, (III), and 2,4,6-triaminopyrimidinium 5-chlorothiophene-2-carboxylate, C₄H₈N₅⁺·C₅H₂ClO₂S⁻, (IV). All four salts exhibit robust homomeric and heteromericR₂²(8) ring motifs. Salts (I) and (II) develop sextuple [in (I)] and quadruple [in (I) and (II)] hydrogen-bonded arrays through fused-ring motifs. Salt (II) exhibits a rosette-like architecture. Salt (IV) is isostructural and isomorphous with salt (III), exhibiting an identical crystal structure with a different composition and an identical supramolecular architecture. In salts (III) and (IV), a linear hetero-tetrameric motif is formed and, in addition, both salts exhibit halogen–π interactions which enhance the crystal stability. All four salts develop a supramolecular hydrogen-bonded pattern facilitated by several N—H...O and N—H...N hydrogen bonds with multiple furcated donors and acceptors. 

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