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1. A Janus carbaporphyrin pseudo-dimer

   https://doi.org/10.1038/s41467-024-47239-y  

   He, Haodan; Lee, Jiyeon; Zong, Zhaohui; Kim, Jiwon; Lynch, Vincent M; Oh, Juwon; Kim, Dongho; Sessler, Jonathan L; Ke, Xian-Sheng (April 2024, Nature Communications)

   LeBot, Nathalie; Larochelle, Stephane; Bergin, Enda; Saini, Prabhjot (Ed.)

   Abstract Carbaporphyrin dimers, investigated for their distinctive electronic structures and exceptional properties, have predominantly consisted of systems containing identical subunits. This study addresses the associated knowledge gap by focusing on asymmetric carbaporphyrin dimers with Janus-like characteristics. The synthesis of a Janus-type carbaporphyrin pseudo-dimer5is presented. It displays antiaromatic characteristics on the fused side and nonaromatic behavior on the unfused side. A newly synthesized tetraphenylene (TPE) linked bis-dibenzihomoporphyrin8and a previously reported dibenzo[g,p]chrysene (DBC) linked bis-dicarbacorrole9were prepared as controls. Comprehensive analyses, including¹H NMR spectral studies, single crystal X-ray diffraction analyses, and DFT calculations, validate the mixed character of5. A further feature of the Janus pseudo-dimer5is that it may be transformed into a heterometallic complex, with one side coordinating a Cu(III) center and the other stabilizing a BODIPY complex. This disparate regiochemical reactivity underscores the potential of carbaporphyrin dimers as versatile frameworks, with electronic features and site-specific coordination chemistry controlled through asymmetry. These findings position carbaporphyrin dimers as promising candidates for advances in electronic structure studies, coordination chemistry, materials science, and beyond. 

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2. Di(hydroperoxy)adamantane adducts: synthesis, characterization and application as oxidizers for the direct esterification of aldehydes

   https://doi.org/10.1039/d1dt03243g  

   Arp, Fabian F.; Ashirov, Rahym; Bhuvanesh, Nattamai; Blümel, Janet (November 2021, Dalton Transactions)

   The di(hydroperoxy)adamantane adducts of water (1) and phosphine oxides p -Tol 3 PO·(HOO) 2 C(C 9 H 14 ) (2), o -Tol 3 PO·(HOO) 2 C(C 9 H 14 ) (3), and Cy 3 PO·(HOO) 2 C(C 9 H 14 ) (4), as well as a CH 2 Cl 2 adduct of a phosphole oxide dimer (8), have been created and investigated by multinuclear NMR spectroscopy, and by Raman and IR spectroscopy. The single crystal X-ray structures for 1–4 and 8 are reported. The IR and 31 P NMR data are in accordance with strong hydrogen bonding of the di(hydroperoxy)adamantane adducts. The Raman ν (O–O) stretching bands of 1–4 prove that the peroxo groups are present in the solids. Selected di(hydroperoxy)alkane adducts, in combination with AlCl 3 as catalyst, have been applied for the direct oxidative esterification of n -nonyl aldehyde, benzaldehyde, p -methylbenzaldehyde, p -bromobenzaldehyde, and o -hydroxybenzaldehyde to the corresponding methyl esters. The esterification takes place in an inert atmosphere, under anhydrous and oxygen-free conditions, within a time frame of 45 minutes to 5 hours at room temperature. Hereby, two oxygen atoms per adduct assembly are active with respect to the quantitative transformation of the aldehyde into the ester. 

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3. Thermodynamics of pillararene·guest complexation: blinded dataset for the SAMPL9 challenge

   https://doi.org/10.1039/D1NJ05209H  

   Deng, Chun-Lin; Cheng, Ming; Zavalij, Peter Y.; Isaacs, Lyle (January 2022, New Journal of Chemistry)

   We report an investigation of the complexation between a water soluble pillararene host (WP6) and a panel of hydrophobic cationic guests (G1–G20) by a combination of 1 H NMR spectroscopy and isothermal titration calorimetry in phosphate buffered saline. We find that WP6 forms 1 : 1 complexes with K a values in the 10 4 –10 9 M −1 range driven by favorable enthalpic contributions. This thermodynamic dataset serves as blinded data for the SAMPL9 challenge. 

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4. Conformationally Rigid Cyclic Tungsten Bis-Alkyne Complexes Derived from 1,1’-Dialkynylferrocenes

   https://doi.org/10.1016/j.jorganchem.2017.05.048  

   Curran, T. P.; Lawrence, A. P.; Murtaugh, T. S.; Ji, W.; Pokharel, N.; Gober, C. B.; Suitor, J. (October 2017, Journal of organometallic chemistry)

   In exploring the conformational behavior of cyclic tungsten bis-alkyne complexes, two dialkynylamides (14a and 14c) and two dialkynylesters (14b and 14d) derived from 1,1’-ferrocenedicarboxylic acid were prepared. They were subsequently reacted with W(CO)3(dmtc)2 to yield the desired cyclic tungsten bis-alkyne complexes 8-11. In the cyclization of 14a to yield 8 a dimeric macrocyclic complex, 15, featuring two tungsten bis-alkyne complexes in the ring, also was isolated. The conformational behavior of these complexes was assessed by analysis of the 1H NMR resonances for the alkyne hydrogens, which appear around 11 ppm. The spectra for complexes 10, 11 and 15 show multiple singlets of varying integrations for these protons, while the spectra for complexes 8 and 9 show only two resonances of equal integration for the alkyne hydrogens. The spectra for 8 and 9 changed very little when examined at higher temperatures, indicating that the solution conformation is robust. A ROESY spectrum was obtained for 8. It did not show any crosspeaks between the two alkyne hydrogens. The NMR data shows that the alkyne ligands in 10, 11 and 15 are able to rotate about the tungsten-alkyne bond; these complexes adopted several different solution conformations relating to syn and anti arrangements of the alkyne ligands. In contrast, complexes 8 and 9 adopt only one solution conformation, and the alkyne ligands in these species do not rotate about the tungsten-alkyne bond. The NMR spectra for 8 and 9 also show that these complexes are asymmetric. The 1H NMR spectra for 8 and 9 show that each hydrogen atom has its own unique resonance in the 1H NMR spectrum. There are 8 resonances for the 8 Cp protons, 4 resonances for the methylene protons, 2 resonances for the alkyne protons, and in the case of 8, 2 resonances for the NH protons. The two NH protons on complex 8 were found to have widely different chemical shifts. A DMSO titration was performed and it showed that one of the two NH protons in 8 is involved in an intramolecular hydrogen bond. Given that the diester 9 adopts a similar conformation as the diamide 8, this intramolecular hydrogen bond appears to result from the conformation imposed by cyclization of the ring system. Overall, the data show that the ring system for 8 and 9 provides a unique, rigid, robust, and air stable cyclic molecule where the alkyne ligands are limited to one orientation, presumably the syn orientation. The lack of mobility for the alkyne ligands limits the cyclic molecule to only one solution conformation. Complexes 8 and 9 are the first reported examples of cyclic tungsten bis-alkyne complexes that only adopt a single, robust conformation in solution. 

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5. Fusing 10-vertex closo -carborane anions with N-heterocyclic carbenes

   https://doi.org/10.1039/D2CC02596E  

   Tej Raviprolu, Varun; McArthur, Sarah E.; Banda, Isaac; Gregory, Aaron; McArthur, Scott G.; Fisher, Steven P.; Lavallo, Vincent (September 2022, Chemical Communications)

   Discovered by Knöth in 1964, the 10-vertex closo -carborane anion [HCB 9 H 9 1− ] is a classical bicapped square antiprism that contains an unusual pentacoordinate carbon center. Compared to its larger icosahedral cousin [HCB 11 H 11 1− ], few investigations have been made into its use as a weakly coordinating anion or as a ligand substituent. Here we show that it is possible to prepare both a dianionic N-heterocyclic carbene (NHC) Li + adduct as well as a trianionic C-2, C-5 dilithio species featuring two 10-vertex carborane anion substituents. All compounds were characterized via multinuclear NMR spectroscopy, single crystal X-ray diffraction, and HRMS when possible. 

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