Dawson结构杂多阴离子(P2M18O62)6-(M=Mo,W)的电子结构和催化性质的理论研究

用第一原理密度泛函理论的离散变分方法(DFT-DVM)计算典型的Dawson结构杂多阴离子(P₂M₁₈O₆₂)^6-(M=Mo,W)的电子结构,比较两者之间的差异。结果表明,Dawson结构中极位和赤道位的原子有不同的化学行为,还原电子将主要进入赤道位的金属原子。(P₂Mo₈O₆₂)^6-的反应活性中心主要是配位金属原子Mo、极位桥氧O_pb、赤道位端氧O_et和赤道位中心氧O_ei;(P₂W₁₈O₆₂)^6-的反应活性中心主要是配位金属原子W、极位桥氧O_pb、赤道位端氧O_et.(P₂Mo₈O₆₂)^6-的氧化性强于(P₂W₁₈O₆₂)^6-,而酸性则与此相反。这与Keggin结构(PM₁₂O₄₀)^3-杂多阴离子的情况相同。

Studies on the Relationship Between Electronic Structuresand Catalytic Properties of Dawson HPA Anion

The electronic structures of Dawson HPA anion(P2M18O62)6-(M=Mo,W) have been calculat-ed by the discrete variational method coupled with the first principle density functional theory (DFT-DVM). The results show that the difference of the chemical properties of polar and equator sites exists.The reduction electrons will be introduced mainly into equatorial metal atoms. The active centers of(P2Mo18O62)6- are Mo, Opb, Oet, Oei and that of (P2W18O62)6- are W, Opb, Oet The redox effect of(P2Mo18O62)6- is stronger than that of (P2W18O62)6-, but their acidities are quite the opposite, which areall the same as those of (PM12O40)3- (M=Mo, W).