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1. Synthesis, molecular and crystal structures of 4-amino-3,5-difluorobenzonitrile, ethyl 4-amino-3,5-difluorobenzoate, and diethyl 4,4′-(diazene-1,2-diyl)bis(3,5-difluorobenzoate)

   https://doi.org/10.1107/S2056989024006819  

   Novikov, Egor M; Guillen_Campos, Jesus; Read_de_Alaniz, Javier; Fonari, Marina S; Timofeeva, Tatiana V (August 2024, Acta Crystallographica Section E Crystallographic Communications)

   The crystal structures of two intermediates, 4-amino-3,5-difluorobenzonitrile, C₇H₄F₂N₂(I), and ethyl 4-amino-3,5-difluorobenzoate, C₉H₉F₂NO₂(II), along with a visible-light-responsive azobenzene derivative, diethyl 4,4′-(diazene-1,2-diyl)bis(3,5-difluorobenzoate), C₁₈H₁₄F₄N₂O₄(III), obtained by four-step synthetic procedure, were studied using single-crystal X-ray diffraction. The molecules ofIandIIdemonstrate the quinoid character of phenyl rings accompanied by the distortion of bond angles related to the presence of fluorine substituents in the 3 and 5 (ortho) positions. In the crystals ofIandII, the molecules are connected by N—H...N, N—H...F and N—H...O hydrogen bonds, C—H...F short contacts, and π-stacking interactions. In crystal ofIII, only stacking interactions between the molecules are found. 

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2. Crystal structure of a μ-oxo vanadium(V) dimer coordinated by a salan ligand

   https://doi.org/10.1107/S2056989025008631  

   Kallingal, Isha A; Alvarado, Anais A; Stieber, S_Chantal E; John, Alex (November 2025, Acta Crystallographica Section E Crystallographic Communications)

   Aμ-oxo vanadium(V) dimeric complex, μ-oxido-bis[(2,2′-{[ethane-1,2-diylbis(azanediyl)]bis(methylene)}diphenolato)oxidovanadium(V)], [V₂(C₁₆H₁₈N₂O₂)₂O₃] (1), was crystallized by slow evaporation from an ethanol solution. Theμ-oxo dimer crystallizes in the monoclinic space groupC2/cwhere the salan ligand1acoordinates to the vanadium center in a κ²N,κ²Ofashion, forming a distorted octahedral geometry. The bridging oxo ligand lies on a crystallographic twofold axis. The unit cell consists of four molecules of1that are linked by C—H...·π_areneinteractions as well as intramolecular hydrogen bonding. 

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3. Crystal structure of 4-bromo-5,7-dimethoxy-2,3-dihydro-1 H -inden-1-one

   https://doi.org/10.1107/S2056989024006522  

   Galla, Sri Hari; Sridhar, Jayalakshmi; Mague, Joel T; Zhang, Xiaodong; White, Kira D; Zhang, Qiang; Donahue, James P (August 2024, Acta Crystallographica Section E Crystallographic Communications)

   In the title molecule, C₁₁H₁₁BrO₃, the dihydroindene moiety is essentially planar but with a slight twist in the saturated portion of the five-membered ring. The methoxy groups lie close to the above plane. In the crystal, π-stacking interactions between six-membered rings form stacks of molecules extending along thea-axis direction, which are linked by weak C—H...O and C—H...Br hydrogen bonds. A Hirshfeld surface analysis was performed showing H...H, O...H/H...O and Br...H/H...Br contacts make the largest contributions to intermolecular interactions in the crystal. 

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4. A Nontemplated Route to Macrocyclic Dibridgehead Diphosphorus Compounds: Crystallographic Characterization of a “Crossed‐Chain” Variant of in / out Stereoisomers

   https://doi.org/10.1002/asia.201800739  

   Kharel, Sugam; Jia, Tiezheng; Bhuvanesh, Nattamai; Reibenspies, Joseph_H; Blümel, Janet; Gladysz, John_A (August 2018, Chemistry – An Asian Journal)

   Abstract Reactions of (O=)PH(OCH₂CH₃)₂and BrMg(CH₂)_mCH=CH₂(4.9–3.2 equiv;m=4 (a), 5 (b), 6 (c)) give the dialkylphosphine oxides (O=)PH[(CH₂)_mCH=CH₂]₂(2 a–c; 77–81 % after workup), which are treated with NaH and then α,ω‐dibromides Br(CH₂)_nBr (0.49–0.32 equiv;n=8 (a′), 10 (b′), 12 (c′), 14 (d′)) to yield the bis(trialkylphosphine oxides) [H₂C=CH(CH₂)_m]₂P(=O)(CH₂)_n(O=)P[(CH₂)_mCH=CH₂]₂(3 ab′,3 bc′,3 cd′,3 ca′; 79–84 %). Reactions of3 bc′and3 ca′with Grubbs’ first‐generation catalyst and then H₂/PtO₂afford the dibridgehead diphosphine dioxides(4 bc′,4 ca′; 14–19 %,n′=2m+2);³¹P NMR spectra show two stereoisomeric species (ca. 70:30). Crystal structures of two isomers of the latter are obtained,out,out‐4 ca′and a conformer ofin,out‐4 ca′that features crossed chains, such that the (O=)P vectors appearout,out. Whereas4 bc′resists crystallization, a byproduct derived from an alternative metathesis mode, (CH₂)₁₂P(=O)(CH₂)₁₂(O=)P(CH₂)₁₂, as well as3 ab′and3 bc′, are structurally characterized. The efficiencies of other routes to dibridgehead diphosphorus compounds are compared. 

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5. Some thioether-ketones and their related derivatives

   https://doi.org/10.1107/S2056989025004037  

   O'Connor, Molly A; Pavlishchuk, Anna V; Butcher, Raymond J; Pavlishchuk, Vitaly V; Addison, Anthony W (June 2025, Acta Crystallographica Section E Crystallographic Communications)

   Structural characteristics are reported for two thioether–ketones,DtdpeandMtdp[2-({2-[(2-oxo-2-phenylethyl)sulfanyl]ethyl}sulfanyl)-1-phenylethan-1-one, C₁₈H₁₈O₂S₂, and 2-[(2-oxo-2-phenylethyl)sulfanyl]-1-phenylethan-1-one, C₁₆H₁₄O₂S], and for related derivatives, the bis(pyridylhydrazones)DhpkandPrpsb[2-((2E)-2-{(2Z)-2-phenyl-2-[2-(pyridin-2-yl)hydrazin-1-ylidene]ethylidene}hydrazin-1-yl)pyridine, C₁₈H₁₆N₆, and 2-[(2Z,12Z)-3,12-diphenyl-14-(pyridin-2-yl)-5,10-dithia-1,2,13,14-tetraazatetradeca-2,12-dien-1-yl]pyridine, C₃₀H₃₂N₆S₂], as well as for the macrocyclic thiocarbohydrazide derivativeCtrsp[(3E,8Z)-3,9-dimethyl-1,11-dithia-4,5,7,8-tetraazacyclotetradeca-3,8-diene-6-thione, C₁₀H₁₈N₄S₃]. Three of the five compounds exhibit conformational enantiomerism in the solid state. The occurrence of intra- and intermolecular hydrogen bonding is commented upon through quantum mechanical (DFT) calculations. Weak C—H...S interactions are noted, while stronger N—H...N and N—H...S hydrogen bridges are delineated. 

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