Iodide-Coordinated Single-Site Pd Catalysts for Alkyne Dialkoxycarbonylation

Abstract

Heterogeneous single-metal-site catalysts (HSMSCs) have attracted considerable interest, but most studies have focused on the metal atoms in the active site while ignoring the key role of ligands. The unique coordination environment of a single-site catalyst is crucial for realizing its potential. Constructing this kind of catalyst via a feasible and practical fabrication method is challenging. Herein, a single-site Pd catalyst with iodide ligands supported on activated carbon (Pd1/AC) was successfully fabricated by atomic dispersion of large Pd nanoparticles (NPs). Intermediate I• radicals were detected during the atomic dispersion process of Pd NPs by in situ imaging photoelectron photoion coincidence spectroscopy (in situ iPEPICO) with vacuum ultraviolet synchrotron radiation. The molecular structure of single-site Pd was established as [Pd­(CO)­I4(OAC)]2– through combined characterization. Alkyne dialkoxycarbonylation with high selectivity toward 1,4-dicarboxylic acid esters (>94%) and high acetylene conversion (>99%) was achieved. A sulfonic promoter on the Pd1/AC catalyst for alkyne dialkoxycarbonylation was avoided because of the iodide ligand. Good durability and a broad substrate scope were successfully achieved.

Pd speciation on black phosphorene in a CO and C2H4 atmosphere: a first-principles investigation

“…Previously, positively charged Pd species were reported efficient for a series of conversion of organic compounds of industrial significance, such as carbonylation and decarbonylation, [77][78][79] hydrogenation and dehydrogenation of unsaturated organic compounds, [35][36][37][38][39][40][41][42][43][44][45] etc., 80 making it interesting to investigate the evolution of Pd atom and Pd atomic strips on phosphorene in realistic conditions (T, P) relevant to experiments.…”

Understanding Synthesis–Structure–Performance Correlations of Nanoarchitectured Activated Carbons for Electrochemical Applications and Carbon Capture

“…[ 468 ] With regard to the atomically dispersed Pd/activated carbon composites, the I• radical intermediates were identified, and the molecular structural formula was recognized as [Pd(CO)I 4 (O = AC)] 2– . [ 469 ] The Mitlin team covered a homogeneous layer of MnO nanoparticles (20‐50 nm) on both sides of the activated carbon nanosheets, which were immobilized by the pore terminations. The small size of the pore‐confined MnO nanocrystallites led to a short Li + diffusion length (≈20 nm) and high rates.…”

Palladium-catalyzed regio- and stereoselective alkoxycarbonylation of unsymmetrical internal alkynes toward α, β-unsaturated succinates

“…In addition, it also has a wide range of applications in industry (such as beverages, cosmetics) [32][33][34][35][36][37]. Accordingly, much effort has been devoted to developing new synthetic methods to establish such a structure (Scheme 1B) [38][39][40][41][42][43][44][45][46][47][48][49][50]. For example, Chatani and co-workers accomplished a Rh-catalyzed alkoxycarbonylation of internal alkynes to construct saturated succinates by using special alcohol, pyridine-2-ylmethanol [40].…”