期刊
MOLECULAR PHYSICS
卷 107, 期 1, 页码 53-58出版社
TAYLOR & FRANCIS LTD
DOI: 10.1080/00268970802705740
关键词
Lindqvist-type polyanions; electronic structures; redox properties; density functional theory
资金
- National Natural Science Foundation of China [20701005/20701006]
- Science and Technology Development Project Foundation of Jilin Province [20060420]
- Postdoctoral Station Foundation of the Ministry of Education [20060200002]
- Testing Foundation of Northeast Normal University
- Program for Changjiang Scholars and Innovative Research Team
Calculations based on density functional theory have been carried out to investigate the electronic and redox properties of a series of Lindqvist-type polyanions: [W5O18Zr(H2O)3-n(DMSO)n]2- (n = 0, 1, and 2), [W5O18M(H2O)3]2- (M = Ti and Hf), and [Mo5O18M(H2O)3]2- (M = Ti, Zr, and Hf). The results show that fragments of {Zr(H2O)3-n(DMSO)n}4+ (n = 0, 1, and 2) modify the HOMO-LUMO energy gaps of [W5O18Zr(H2O)3-n(DMSO)n]2- (n = 0, 1, and 2), which are lower than that of the related parent [W6O19]2-. Therefore, they are more easily reduced than their parent species. The LUMO of [W5O18Zr(H2O)3]2- mainly localizes on the d-orbitals of W (61.71%), and LUMO + 1 mainly concentrates on the W atoms, the contribution of Zr being only 2.38%. Thus, W atoms will preferentially accept an electron when [W5O18Zr(H2O)3]2- is reduced as a catalysts, which is reinforced by the spin density of the monoreduced species. However, the electronic properties of [W5O18Ti(H2O)3]2- are different from those of [W5O18Zr(H2O)3]2- and [W5O18Hf(H2O)3]2-. The substituting metal Ti effectively modifies the electronic properties of [W5O18Ti(H2O)3]2-. The LUMO of [W5O18Ti(H2O)3]2- is mainly concentrated on the Ti atom. Thus, the Ti atom of [W5O18Ti(H2O)3]2- becomes the reduced center, which means that different metal substitutions can alter the reduced center. In addition, the replacement of five W atoms by five Mo atoms in [Mo5O18M(H2O)3]2- (M = Zr, Ti, and Hf) significantly reduces the HOMO-LUMO energy gap, which indicates that Ti/Zr/Hf-Mo polynuclear Lindqvist complexes may make promising catalysts. It is hoped that the results presented here will give some impetus to interrelated studies.
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