Intermediates of Carbon Monoxide Oxidation on Praseodymium Monoxide Molecules: Insights from Matrix-Isolation IR Spectroscopy and Quantum-Chemical Calculations

Zhen Pu; Jianwei Qin; Bingyun Ao; Haopeng Dong; Maobing Shuai; Fang Li

doi:10.1021/acs.inorgchem.0c03607

Intermediates of Carbon Monoxide Oxidation on Praseodymium Monoxide Molecules: Insights from Matrix-Isolation IR Spectroscopy and Quantum-Chemical Calculations

Inorg Chem. 2021 Jun 7;60(11):7660-7669. doi: 10.1021/acs.inorgchem.0c03607. Epub 2021 May 21.

Authors

Zhen Pu¹, Jianwei Qin², Bingyun Ao², Haopeng Dong¹, Maobing Shuai¹, Fang Li³

Affiliations

¹ Institute of Materials, China Academy of Engineering Physics, Mailbox No. 9-21, Huafengxincun, Jiangyou 621908, Sichuan, P. R. China.
² Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, Sichuan, China.
³ School of Material Science and Engineering, Southwest University of Science and Technology, 59 Middle Section of Qinglong Road, Mianyang 621010, Sichuan, P.R. China.

PMID: 34018728
DOI: 10.1021/acs.inorgchem.0c03607

Abstract

Identifying reaction intermediates in gas-phase investigations will provide understanding for the related catalysts in fundamental aspects including bonding interactions of the reaction species, oxidation states (OSs) of the anchored atoms, and reaction mechanisms. Herein, carbon monoxide (CO) oxidation by praseodymium monoxide (PrO) molecules has been investigated as a model reaction in solid argon using matrix-isolation IR spectroscopy and quantum-chemical calculations. Two reaction intermediates, OPr(η¹-CO) and OPr(η²-CO), have been trapped and characterized in argon matrixes. The intermediate OPr(η²-CO) shows an extremely low C-O stretching band at 1624.5 cm^-1. Quantum-chemistry studies indicate that the bonding in OPr(η¹-CO) is described as "donor-acceptor" interactions conforming to the Dewar-Chatt-Duncanson motif. However, the bonding in OPr(η²-CO) results evidently from a combination of dominant ionic forces and normal Lewis "acid-base" interactions. The electron density of the singly occupied bonding orbital is strongly polarized to the CO fragment in OPr(η²-CO). Electronic structure analysis suggests that the two captured species exhibit Pr(III) OSs. Besides, the pathways of CO oxidation have been discussed.