Search for: All records

Abstract Palladium-catalyzed dehydrogenation of formic acid under homogeneous conditions is rare. In most cases, decomposition of palladium complexes is observed under the reaction conditions. In this study, bis(phosphinite)-supported palladium(II) complexes, {2,6-(R2PO)2C6H3}PdX [R = iPr, tBu; X = H (1a–b), OCHO (2a–b)], were examined for catalytic formic acid dehydrogenation (FAD). Their derivative complexes, {2,6-(R2PO)2C6H3}PdCH3 (3a–b), were found to be precatalysts. During catalysis, complex degradation was observed; however, by optimizing the reaction conditions (80 °C, ethanol), a homogeneous and additive-free procedure for FAD was achieved. Alcohols and dihydrogen were identified as the possible sources of catalyst decomposition. Mechanistic investigations reveal that the protonation of {2,6-(R2PO)2C6H3}PdH (1a–b) is both kinetically and thermodynamically favored, which drives FAD while suppressing catalyst degradation pathways. It was found that the sterically crowded {2,6-(tBu2PO)2C6H3}PdCH3 (3b) is a more effective catalyst compared to {2,6-(iPr2PO)2C6H3}PdCH3 (3a). Experimental data show that CO2 elimination, the rate-limiting step of the catalytic cycle, occurs more rapidly from {2,6-(tBu2PO)2C6H3}PdOCHO (2b) than from {2,6-(iPr2PO)2C6H3}PdOCHO (2a), thereby accelerating the overall reaction rate. 

Other: Related Article: Mahmood Ahmadianpoor, Jeanette A. Krause, Hairong Guan |2026|CSD Communication||| Abstract: An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures. 

Other: Related Article: Anusha Biswas, Jeanette A. Krause, Hairong Guan|2026|CSD Communication||| Abstract: An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures. 

Cobalt(II) acetylacetonate complexes bearing a phosphine ligand can be key intermediates or precursors to cobalt‐based catalysts; however, they have been rarely studied, especially from a molecular structure point of view. This work is focused on the understanding of how different phosphines react with Co(acac)₂(acac = acetylacetonate). To do so, a variety of analytical tools, including NMR and IR spectroscopy, X‐ray crystallography, mass spectrometry, and elemental analysis, have been used to study the reactions and characterize the isolated products. These results have shown that the monodentate ligand, HPPh₂, binds to Co(acac)₂weakly and reversibly to produce Co₂(acac)₄(HPPh₂), whereas the bidentate ligand, 1,2‐bis(diphenylphosphino)ethane (dppe), interacts with Co(acac)₂more strongly to yield a 1D coordination polymer of Co(acac)₂(dppe). 2‐(Dicyclohexylphosphino)methyl‐1 H‐pyrrole (^CyPN^H), which is a pyrrole‐tethered phosphine, forms an unusual 5‐coordinate cobalt complex, Co(acac)₂(^CyPN^H), in which the pyrrole moiety participates in a bifurcated hydrogen–bonding interaction with the [acac]^–ligands. In contrast, another bidentate ligand, 4,5‐bis(diphenylphosphino)‐9,9‐dimethylxanthene (xantphos), fails to react with Co(acac)₂, presumably due to its wide bite angle and difficulty in bridging two metals. 

A dodecanuclear copper hydride L₄Cu₁₂H₁₂is shown to be a transient species after the cluster expansion from L₂Cu₄H₄to L₃Cu₆H₆and before the degradation to Cu(0), L, and H₂. 

Other: Related Article: Krishna Pokhrel, Jeanette A. Krause, Hairong Guan |2025|CSD Communication||| Abstract: An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures. 

Other: Related Article: Ananda Karki, Jeanette A. Krause, Hairong Guan|2025|CSD Communication||| Abstract: An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures. 

Other: Related Article: Sayantani Saha, Jeanette A. Krause, Hairong Guan|2025|CSD Communication||| Abstract: An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.