Ai-Guo Zhong

Theoretical study on the reactions of Zr+ and Zr with CO2 in gas phase

Density functional theory (DFT) calculations have been performed to explore the potential energy surfaces of C-O bond activation in CO2 molecule by gas-phase Zr+ cation and Zr atom, for better understanding the mechanism of second-row transition metal reacting with CO2. The minimum energy reaction path is found to involve the spin inversion in the different reaction steps. This potential energy curvecrossing dramatically affects reaction energetics. The present results show that the reaction mechanism is insertion-elimination mechanism along the C-O bond activation. All theoretical results not only support the existing conclusions inferred from early experiment, but also complement the pathway and mechanism for this reaction.

CARBON DIOXIDE ACTIVATION BY Y ATOM AND Y+ CATION IN THE GAS PHASE: A DENSITY FUNCTIONAL THEORETICAL STUDY

ABSTRACT The potential energy surfaces for the Y+CO 2 and Y + +CO 2 reactions have been investigated by using the DFT (B3LYP/ECP/6−311+G*) level of theory. Both ground and excited state potential energy surfaces are discussed. The present results show that the reaction mechanism is an insertion mechanism along the C−O bond activation branch. The reaction of Y atom with CO 2 was shown to occur preferentially on the doublet PES throughout the reaction process. As for the reaction between Y + cation with CO 2 , it involves potential energy curve-crossing which dramatically affects reaction mechanism. Due to the intersystem crossing existing in the reaction process of Y + with CO 2 , the intermediate (OY(η 2 CO)) + may not form. This mechanism is different from that of Y + CO 2 system. All our theoretical results not only support the existing conclusions inferred from early experiment, but also complement the pathway and mechanism for this reaction. Keywords: DFT theory, Potential energy surface, Intersystem, Yttrium

Theoretical investigation of the reactions of La atom and La+ cation with carbonyl sulfide

The potential energy surfaces for the La+SCO and La++ SCO reactions have been theoretically investigated by using the DFT (B3LYP/ECP/6-311+G(2d)) level of theory. Both ground and excited state potential energy surfaces (PES) are discussed. The present results show that the reaction mechanism is insertion mechanism both along the C-S and C-O bond activation branches, but the C-S bond activation is much more favorable in energy than the C-O bond activation. The reaction of La atom with SCO was shown to occur preferentially on the ground state (doublet) PES throughout the reaction process, and the experimentally observed species, have been explained according to the mechanisms revealed in this work. While for the reaction between La+ cation with SCO, it involves potential energy curve-crossing which dramatically affects reaction mechanism, and the crossing points (CPs) have been localized by the approach suggested by Yoshizawa et al. Due to the intersystem crossing existing in the reaction process of La+ with SCO, the products SLa+(η2CO) and OLa+(η2CS) may not form. This mechanism is different from that of La + SCO system. All our theoretical results not only support the existing conclusions inferred from early experiment, but also complement the pathway and mechanism for this reaction.