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1. Using Phosphonic Acid Monolayers to Control CO ₂ Adsorption and Hydrogenation on Pt/Al ₂ O ₃

   https://doi.org/10.1002/cctc.202400451  

   Blanchette, Zachary; Zhou, Xinpei; Schwartz, Daniel_K; Medlin, J_Will (August 2024, ChemCatChem)

   Abstract Phosphonic acid (PA) self‐assembled monolayers (SAMs) were deposited onto Pt/Al₂O₃catalysts to modify the support to enable control over CO₂adsorption and CO₂hydrogenation activity. Significant differences in catalytic activity toward CO₂hydrogenation (reverse water‐gas shift, RWGS) were observed after coating Al₂O₃with PAs, suggesting that the reaction was mediated by CO₂adsorption on the support. Amine‐functionalized PAs were found to outperform their alkyl counterparts in terms of activity, however there was little effect of amine location in the SAM (i. e., spacing between the amine functional group and phosphonate attachment group). One amine‐PA and one alkyl‐PA, aminopropyl phosphonic acid (C₃NH₂PA) and methyl phosphonic acid (C₁PA), respectively, were investigated in more detail. The C₃NH₂PA‐modified catalyst was found to bind CO₂as a combination of carbamate and bicarbonate. Additionally, at 30 °C, both PAs were found to reduce CO₂adsorption uptake by approximately 50 % compared to unmodified 5 %Pt/Al₂O₃. CO₂adsorption enthalpy was measured for the catalysts and found to be strongly correlated with hydrogenation activity, with the trend in binding enthalpy and CO₂hydrogen rate trending as uncoated >C₃NH₂PA>C₁PA. PA SAMs were found to have weaker effects on CO binding and CO selectivity, consistent with selective modification of the Al₂O₃support by the PAs. 

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2. Insertion of CO ₂ Mediated by a (Xantphos)Ni ^I –Alkyl Species

   https://doi.org/10.1002/anie.201906005  

   Diccianni, Justin B.; Hu, Chunhua T.; Diao, Tianning (August 2019, Angewandte Chemie International Edition)

   Abstract The incorporation of CO₂into organometallic and organic molecules represents a sustainable way to prepare carboxylates. The mechanism of reductive carboxylation of alkyl halides has been proposed to proceed through the reduction of Ni^IIto Ni^Iby either Zn or Mn, followed by CO₂insertion into Ni^I‐alkyl species. No experimental evidence has been previously established to support the two proposed steps. Demonstrated herein is that the direct reduction of (tBu‐Xantphos)Ni^IIBr₂by Zn affords Ni^Ispecies. (tBu‐Xantphos)Ni^I‐Me and (tBu‐Xantphos)Ni^I‐Et complexes undergo fast insertion of CO₂at 22 °C. The substantially faster rate, relative to that of Ni^IIcomplexes, serves as the long‐sought‐after experimental support for the proposed mechanisms of Ni‐catalyzed carboxylation reactions. 

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3. Substituent Effect on the Circularly Polarized Luminescence of C ₁ ‐Symmetric Carbene‐Copper(I) Complexes

   https://doi.org/10.1002/cptc.202100068  

   Braker, Erin_E; Mukthar, Nishya_F_M; Schley, Nathan_D; Ung, Gaël (June 2021, ChemPhotoChem)

   Abstract The substituent effect on the magnitude of the circularly polarized luminescence (CPL) of^MentCAAC‐Cu‐X (X=F, Cl, Br, I, BH₄, B₃H₈; CAAC=cyclic (alkyl)(amino)carbenes) complexes is experimentally investigated. This study examines seven pairs of enantiomeric complexes with small anionic substituents (halides, borohydrides, hydride). The complexes are fully characterized, including single crystal X‐ray diffraction studies, and chiroptical measurements show that small covalent anions induce a larger CPL magnitude. These results demonstrate that the magnitude of the CPL can be manipulated without making any modifications to the chiral ligand. 

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4. Electronic Structure of trans‐ [V ^II Cl ₂ (E(CH ₃ ) ₂ CH ₂ CH ₂ E(CH ₃ ) ₂ ) ₂ ], E=N, P

   https://doi.org/10.1002/ejic.202400395  

   Jafari, Mehrafshan_G; Zolnhofer, Eva_M; Fehn, Dominik; Heinemann, Frank_W; Opalade, Adedamola_A; Carroll, Patrick_J; Meyer, Karsten; Krzystek, J.; Ozarowski, Andrew; Mindiola, Daniel_J; et al (December 2024, European Journal of Inorganic Chemistry)

   Abstract Coordination complexes of general formulatrans‐[MX₂(R₂ECH₂CH₂ER₂)₂] (M^II=Ti, V, Cr, Mn; E=N or P; R=alkyl or aryl) are a cornerstone of coordination and organometallic chemistry. We investigate the electronic properties of two such complexes,trans‐[VCl₂(tmeda)₂] andtrans‐[VCl₂(dmpe)₂], which thus representtrans‐[MX₂(R₂ECH₂CH₂ER₂)₂] where M=V, X=Cl, R=Me and E=N (tmeda) and P (dmpe). These V^IIcomplexes haveS=3/2 ground states, as expected for octahedral d³. Their tetragonal distortion leads to zero‐field splitting (zfs) that is modest in magnitude (D≈0.3 cm⁻¹) relative to analogousS=1 Ti^IIand Cr^IIcomplexes. This parameter was determined from conventional EPR spectroscopy, but more effectively from high‐frequency and ‐field EPR (HFEPR) that determined the sign ofDas negative for the diamine complex, but positive for the diphosphine, which information had not been known for anytrans‐[VX₂(R₂ECH₂CH₂ER₂)₂] systems. The ligand‐field parameters oftrans‐[VCl₂(tmeda)₂] andtrans‐[VCl₂(dmpe)₂] are obtained using both classical theory andab initioquantum chemical theory. The results shed light not only on the electronic structure of V^IIin this environment, but also on differences between N and P donor ligands, a key comparison in coordination chemistry. 

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5. Effective Selection and Targeted Passivation for Different Defect Types by Ammonium Salts in Perovskite Solar Cells

   https://doi.org/10.1002/aenm.202500678  

   Qi, Yifang; Aguinaga, Jeffrey; Terlier, Tanguy; Qiu, Chuchu; Zhang, Haixin; Upreti, Saroj; Johnson, Italian; Glover, Jordan; Hang, Rui; He, Sheng; et al (September 2025, Advanced Energy Materials)

   Abstract The optimal selection of alkyl chains and halogen ions in ammonium salts for addressing specific defect types in perovskite films remains unclear, although ammonium salts emerged as a promising strategy to enhance the performance of perovskite solar cells (PSCs). Herein, four ammonium salts are introduced with different alkyl chain types and halogen ions to passivate perovskite films. Branched‐alkyl chain ammonium salts exhibited superior passivation effects compared to linear‐alkyl chain salts, with the alkyl chain structure having a more significant impact on device performance than the halogen ion component. In addition, DFT calculations are performed to investigate which defect types in perovskite films are most effectively passivated by different alkyl chain types and halogen ions in ammonium salts. Branched‐alkyl chain ammonium salts demonstrated superior passivation effects on V_Pband V_FAdefects in perovskite films compared to linear‐alkyl chain salts, while exhibiting similar passivation effects for V_Idefects. PSCs passivated with tert‐OAI achieved an impressive efficiency of 25.49%, with a V_ocof 1.19 V, a J_scof 25.40 mA cm⁻², and an FF of 84.34%. This work highlights a targeted ammonium salt passivation strategy tailored to address different defect types in perovskite films, accounting for variations in perovskite composition and fabrication environments. 

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