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1. Coordination-Induced Weakening of a C(sp3)–H Bond: Homolytic and Heterolytic Bond Strength of a CH–Ni Agostic Interaction

   https://doi.org/10.1021/jacs.2c05667  

   Lin, Lirong; Spasyuk, Denis M.; Lalancette, Roger A.; Prokopchuk, Demyan E. (July 2022, Journal of the American Chemical Society)

   The scission of a C(sp3)−H bond to form a new metal−alkyl bond is a fundamental step in coordination chemistry and catalysis. However, the extent of C−H bond weakening when this moiety interacts with a transition metal is poorly understood and quantifying this phenomenon could provide insights into designing more efficient C−H functionalization catalysts. We present a nickel complex with a robust adamantyl reporter ligand that enables the measurement of C−H acidity (pKa) and bond dissociation free energy (BDFE) for a C(sp3)−H agostic interaction, showing a decrease in pKa by dozens of orders of magnitude and BDFE decrease of about 30 kcal/mol upon coordination. X-ray crystallographic data is provided for all molecules, including a distorted square planar NiIII metalloradical and “doubly agostic” NiII(κ2-CH2) complex. 

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2. Cationic magnesium hydride [MgH] ⁺ stabilized by an NNNN-type macrocycle

   https://doi.org/10.1039/C9CC00490D  

   Lemmerz, Lara E.; Mukherjee, Debabrata; Spaniol, Thomas P.; Wong, Anthony; Ménard, Gabriel; Maron, Laurent; Okuda, Jun (March 2019, Chemical Communications)

   A magnesium hydride cation [(L)MgH] + supported by a macrocyclic ligand (L = Me 4 TACD; 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane) has been prepared by partial protonolysis of a mixed amide hydride [(L)MgH 2 Mg{N(SiMe 3 ) 2 } 2 ] and shown to undergo a variety of reactions with unsaturated substrates, including pyridine. 

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3. A Cationic Pt(II) Dinitrogen Adduct: Synthesis and Characterization of a CCC-aNHC Pincer Pt Complex with Abnormal N -Heterocyclic Carbene Donor Arms

   https://doi.org/10.1021/acs.organomet.3c00411  

   Fosu, Evans; Le, Nghia; Abdulraheem, Taofiq; Donnadieu, Bruno; Patrick, Amanda L.; Webster, Charles Edwin; Hollis, T. Keith (February 2024, Organometallics)

   In contrast to the reported CCC-NHC pincer ligands that contain normal N-heterocyclic carbenes (NHC), herein we report an imidazole-based abnormal NHC (aNHC) pincer ligand, CCC-aNHC. The CCC-aNHC pincer Pt complex with two aNHC donors was synthesized via the in situ metalation and transmetalation methodology. The 1,3-phenylene(bis-2-phenyl-3-butyl imidazolium) diiodide salt was reacted with Zr(NMe2)4 to generate a CCC-aNHC pincer zirconium complex in situ. It was transmetalated to Pt using [Pt(COD)Cl2]. Electrospray ionization of the Pt pincer complex [(BuCa‑iCa‑iCBu)-PtI] in acetonitrile generated an intense peak at m/z = 696.2375, which was assigned to the dinitrogen adduct [M−I+N2]+ of the cationic CCC-aNHC pincer Pt(II) complex [(BuCa‑iCa‑iCBu)Pt− N2]+, representing a rare example of the platinum dinitrogen organometallic complex. The super electron-donating ability of the pincer ligands with abnormal NHC enabled the cationic CCC-aNHC pincer Pt(II) complex to selectively bind N2 over MeCN in a first-order analysis. A collision-induced dissociation (CID) study was conducted on the N2 and MeCN adducts, suggesting that more energy was required to dissociate N2 than MeCN. A computational study suggested that the N2 adduct was kinetically stable in the gas phase whereas the MeCN adduct was thermodynamically preferred. The computational results reconciled the mass spectral data experiment with an attempt to isolate the N2 adduct. DFT computation suggested that N2 dissociation is more challenging due to higher energy transition states, and there is a competitive pathway of N2 tumbling within the coordination sphere of the Pt. This tumbling path is not available from the MeCN ligand due to ligand structural differences. 

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4. Al⁺ Activates Acetone to Form Pinacolate

   https://doi.org/10.1021/acs.jpclett.3c01360  

   Phasuk, Apakorn; Metz, Ricardo B (July 2023, The Journal of Physical Chemistry Letters)

   The interaction between aluminum cations and acetone is studied in the gas phase via photodissociation vibrational spectroscopy from 1100 to 2000 cm-1. Spectra of Al+(acetone)(N2) and ions with the stoichiometry of Al+(acetone)n (n=2-5) were measured. The experimental results are compared to DFT calculated vibrational spectra to determine the structures of the complexes. The spectra show a red shift of the C=O stretch and a blue shift of the CCC stretch which decrease as the size of the clusters increases. The calculations predict that the most stable isomer for n≥3 is a pinacolate in which oxidation of the Al+ enables reductive C-C coupling between two acetone ligands. Experimentally, pinacolate formation is observed for n=5, as evidenced by a new peak observed at 1185 cm-1 characteristic of the pinacolate C-O stretch. 

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5. Dissecting crosstalk induced by cell-cell communication using single-cell transcriptomic data

   https://doi.org/10.1038/s41467-025-61149-7  

   Hou, Jiawen; Zhao, Wei; Nie, Qing (December 2025, Nature Communications)

   Abstract During cell-cell communication (CCC), pathways activated by different ligand-receptor pairs may have crosstalk with each other. While multiple methods have been developed to infer CCC networks and their downstream response using single-cell RNA-seq data (scRNA-seq), the potential crosstalk between pathways connecting CCC with its downstream targets has been ignored. Here we introduce a machine learning-based method SigXTalk to analyze the crosstalk using scRNA-seq data by quantifying signal fidelity and specificity, two critical quantities measuring the effect of crosstalk. Specifically, a hypergraph learning method is used to encode the higher-order relations among receptors, transcription factors and target genes within regulatory pathways. Benchmarking of SigXTalk using simulation and real-world data shows the effectiveness, robustness, and accuracy in identifying key shared molecules among crosstalk pathways and their roles in transferring shared CCC information. Analysis of disease data shows SigXTalk’s capability in identifying crucial signals, targets, regulatory networks, and CCC patterns that distinguish different disease conditions. Applications to the data with multiple time points reveals SigXTalk’s capability in tracking the evolution of crosstalk pathways over time. Together our studies provide a systematic analysis of CCC-induced regulatory networks from the perspective of crosstalk between pathways. 

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