Engineering Electronic Structure of Single-Atom Pd Site on Ti _0.87 O ₂ Nanosheet via Charge Transfer Enables C–Br Cleavage for Room-Temperature Suzuki Coupling

Abstract

The palladium (Pd)-catalyzed Suzuki reaction is widely applied in the pharmaceutical industry, where constructing highly active and low-cost Pd sites are impendent. Here, we report the fabrication of a heterogeneous Pd/Tio 2 catalyst via engineering of an electronic structure of a single Pd 1 atom on monolayered Ti 0.87 O 2 nanosheet (Pd 1 -Ti 0.87 O 2 ). This catalyst motivated the kinetically sluggish C-Br cleavage, thus boosting the Suzuki reaction at room temperature. Pd 1 -Ti 0.87 O 2 exhibited an outstanding activity with turnover frequency (TOF) of 11,110 h −1 , exceeding that of PdCl 2 and Pd(OAc) 2 catalysts by a factor of >200. Various in situ techniques were employed to investigate the C-Br activation process, which showed that Pd 1 kinetic-feasibly dissociated the chemisorbed bromobenzene, especially the C-Br bond cleavage. Theoretical calculations further revealed that the improved activity is ascribed to the optimized charge state of Pd 1 within the Pd 1 O 4 realm via charge transfer.

Single‐Atom Catalysis in Organic Synthesis

“…[45] Jin et al further explored the advantage of using a defective oxide (i.e., titania, anatase crystal form) for stabilizing Pd single atoms via charge transfer. [46] This catalyst demonstrated an excellent catalytic function in the Suzuki reaction at room temperature, corroborating the previous results. A TOF up to 11,000 h À 1 with a wide range of substrates was achieved.…”

Single-atom-based catalysts for photoelectrocatalysis: challenges and opportunities

“…4a), more than 200 times that of PdCl 2 and Pd(OAc) 2 catalysts. 54 Hence it can be seen that SACs are competent for various catalytic reactions with tunable active sites and enhanced catalytic activity per site.…”

Surface-Modified Pd/CeO2 Single-Atom Catalyst Shows Increased Activity for Suzuki Cross-Coupling

“…Heterogeneous palladium catalysts are easy to separate but suffer from inefficient metal utilization and nonuniform active sites (e.g., edge, corner, and defects) each exhibiting a different reactivity. − A solution to these issues is found through the use of single-atom catalysts (SACs) composed of individual metal atoms dispersed on a support. SACs combine the easy separability of heterogeneous catalysts with the high metal utilization and site uniformity of homogeneous catalysts, bridging the two fields. , The use of SACs has been well studied for transformations of small molecules, such as water, carbon dioxide, and methane; − however, significantly less work has been done regarding their use in coupling reactions. In several instances, SACs have displayed activity equal to or higher than that of traditional homogeneous catalysts for carbon–carbon coupling reactions. − …”