Keggin型α-[H_xW_(12)O_(40)]^((8-x)-)(x=1～4)中心质子数及笼腔内外质子传递的DFT研究

DFT investigation on the internal proton numbers and their transfer throughout the cage of the Keggin-type α-[H_xW_(12)O_(40)]^((8-x)-)(x=1-4)

采用密度泛函理论研究了Keggin型α-[HxW12O40](8–x)–(x=1~4)的中心容纳质子数以及中心质子通过Keggin笼腔进行内外转移的机理.在O3LYP/LanL2DZ水平下,对气相中各物种结构进行了全优化,得到了质子化前后各物种的稳定构型,找到了质子通过笼腔进行内外转移的过渡态,并用频率分析方法和内禀反应坐标(IRC)方法对各过渡态进行了确证.在极化连续介质模型(PCM)下,考察了体系的溶剂化效应.理论研究不仅阐述了颇有争议的单质子中心和4质子中心物种存在的可能性,而且揭示了质子通过Keggin金属氧笼进行转移和传递的微观机制,理论计算结果与实验事实相一致.

Based on the DFT method,theoretical calculations were applied to investigate the central proton number in the title compound under O3LYP/LanL2DZ level of theory,as well as the mechanism of the central proton transfer throughout the Keggin metal cage.All the species concerned were fully optimized in the gas phase and three transition states TS1,TS2 and TS3,through which the protons were transferred,were found.These TSs were also confirmed using vibration analyses and intrinsic reaction coordinates（IRC） calculation methods.The proton transfer in water solution was also investigated using the SCRF（PCM） method under the same level of theory with 6-31G（d） basis sets on the oxygen atoms.Theoretical results not only showed that the central single-and tetra-protons species may probably exist,but also interpreted the microscopic mechanisms of the proton transfer and migration throughout the Keggin cage.The calculation results were quite in agreement with the experimental ones.