Electronic Properties and Stability of DititaniumIV Substituted -Keggin Polyoxotungstate with Heteroatom Phosphorus by DF
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- 作者：Wei Guan ; Likai Yan ; Zhongmin Su ; Shuxia Liu ; Min Zhang ; and Xiaohong Wang
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：January 10, 2005
- 年：2005
- 卷：44
- 期：1
- 页码：100 - 107
- 全文大小：453K
- 年卷期：v.44,no.1(January 10, 2005)
- ISSN：1520-510X
文摘
The electronic properties, redox properties, protonation, and stability of five [
-PTi2W10O40]7- isomers have beeninvestigated employing density-functional theory (DFT) method. The results reveal that the stability of [-1,2-PTi2W10O40]7- and [-1,6-PTi2W10O40]7- is weaker and the redox ability is higher among five isomers, while for[-1,5-PTi2W10O40]7-, [-1,4-PTi2W10O40]7-, and [-1,11-PTi2W10O40]7- the stability is higher, but the redox abilityis weaker. At the same time, Ti-substituted systems are preferentially reduced in the tungsten centers. A simpleanalysis of molecular electrostatic potential maps of [-PTi2W10O40]7- isomers suggests that the preferred protonationsite corresponds to bridging oxygens (OTi2 and OTiW) and terminal oxygens (OTi), especially bridging oxygensbonded to titaniums (OTi2) in [-1,2-PTi2W10O40]7- and [-PTi2W10O40]7-. It is proposed that the most stable structureis formed preferentially after protonation of the Ti-O site from the study of the protonated species,[-1,4-HPTi2W10O40]6-. By means of total bonding energies of [-PTi2W10O40]7- isomers, the relative sequence ofstability has then been shown to be [-1,4-PTi2W10O40]7- > [-1,5-PTi2W10O40]7- > [-1,11-PTi2W10O40]7- > [-1,2-PTi2W10O40]7- > [-1,6-PTi2W10O40]7-. In addition, the one-electron-reduced species of [-PTi2W10O40]7- are alsodiscussed.
-PTi2W10O40]7- isomers have beeninvestigated employing density-functional theory (DFT) method. The results reveal that the stability of [-1,2-PTi2W10O40]7- and [-1,6-PTi2W10O40]7- is weaker and the redox ability is higher among five isomers, while for[-1,5-PTi2W10O40]7-, [-1,4-PTi2W10O40]7-, and [-1,11-PTi2W10O40]7- the stability is higher, but the redox abilityis weaker. At the same time, Ti-substituted systems are preferentially reduced in the tungsten centers. A simpleanalysis of molecular electrostatic potential maps of [-PTi2W10O40]7- isomers suggests that the preferred protonationsite corresponds to bridging oxygens (OTi2 and OTiW) and terminal oxygens (OTi), especially bridging oxygensbonded to titaniums (OTi2) in [-1,2-PTi2W10O40]7- and [-PTi2W10O40]7-. It is proposed that the most stable structureis formed preferentially after protonation of the Ti-O site from the study of the protonated species,[-1,4-HPTi2W10O40]6-. By means of total bonding energies of [-PTi2W10O40]7- isomers, the relative sequence ofstability has then been shown to be [-1,4-PTi2W10O40]7- > [-1,5-PTi2W10O40]7- > [-1,11-PTi2W10O40]7- > [-1,2-PTi2W10O40]7- > [-1,6-PTi2W10O40]7-. In addition, the one-electron-reduced species of [-PTi2W10O40]7- are alsodiscussed.