2020同步年報

Chemical Science 031 Fig. 4 : Proposed structure of Pd complex using EXAFS structure fitting. [Reproduced from Ref. 3] n Bu H 2 N Pd P( p -tol) 3 OAc OAc The reaction was monitored using the Pd K-edge as shown in Fig. 2(c) . When the reaction mixture was stirred at room temperature, XANES ( Fig. 2(d) ) and EXAFS data ( Fig. 2(c) ) revealed Pd(II) reduction and the formation of a Pd(0)–Pd(0) bond. It is noteworthy that the spectral changes occurred concurrently with the corresponding formation of 2-ynamide. The fitted data of the first QXAFS scan revealed that the Pd coordination environment should be 3 × Pd–N/O (2.05 Å) and 1 × Pd–P (2.30 Å) ( Fig. 4 ). The last QXAFS spectrum indicated the formation of a Pd(0)–Pd(0) bond through reductive elimination and the formation of palladium clusters or nanoparticles under the reaction conditions without electric current ( Fig. 2(c) ). In summary, this work demonstrates that an ideal model of mechanistic studies mainly relied on investigations of potential intermediates. X-ray absorption spectroscopy Fig. 3 : Normalized Pd K-edge XANES of experiment ex situ . [Reproduced from Ref. 3] represents a method to bridge the gap of specific clarifica- tion of local structure and oxidation state of metal centers under an operando mode. That condition will provide nu- merous new opportunities for the optimization of catalysts in more complicated homogeneous catalytic reactions. (Reported by Yi-Hung Chen, Wuhan University, China) This report features the work of Aiwen Lei, Yi-Hung Chen and their collaborators published in Nat. Catal. 3 , 438 (2020). TPS 44A Quick-scanning X-ray Absorption Spectroscopy • XANES, EXAFS, In-situ/Operando • Materials Science, Chemistry, Physics, Environmental Science References 1. B. Gabriele, G. Salerno, L. Veltri, M. Costa, J. Organomet. Chem. 622 , 84 (2001). 2. S. T. Gadge, M. V. Khedkar, S. R. Lanke, C. Zhang, J. Liu, C. Xia, Sci. Technol. 5 , 4750 (2015). 3. L. Zeng, H. Li, J. Hu, D. Zhang, J. Hu, P. Peng, S. Wang, R. Shi, J. Peng, C.-W. Pao, J.-L. Chen, J.-F. Lee, H. Zhang, Y.-H. Chen, A. Lei, Nat. Catal. 3 , 438 (2020).