True Structure of Trigonal Bipyramidal SiO4F- Species in Siliceous Zeolites
True Structure of Trigonal Bipyramidal SiO4F- Species in Siliceous Zeolites
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DOI：
10.1021/cm011141i
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发表时间：
2001-11
影响因子：
8.6
通讯作者：
M. Attfield;C. Catlow;A. Sokol
中科院分区：
文献类型：
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作者：
M. Attfield;C. Catlow;A. Sokol
本文介绍了真正的几何结构的五配位SiO 4F-单元中发现的几个全硅沸石系统，确定从头计算密度泛函计算。研究的两种沸石（方钠石和镁碱沸石）中的SiO 4F-单元含有长度为1.71和1.76 A的Si-F键，并且相对于通常在沸石中发现的四面体SiO 4单元中的Si-O键，单元中的所有Si-O键都是伸长的。SiO 4F-单元中的所有键角与规则三角双锥XY 5单元的预期键角一致。计算出的结构，以准确地再现由标准晶体学方法确定的平均结构模型。我们在这项工作中开发的方法具有普遍的影响，在固体中的复杂的局部结构问题的解决方案。
This paper describes the true geometry of the pentacoordinated SiO4F- units found in several all-silica zeolite systems, as determined by ab initio density functional calculations. The SiO4F- units in the two zeolites (sodalite and ferrierite) studied contain Si−F bonds of 1.71 and 1.76 A in length, and all the Si−O bonds in the units are elongated with respect to the Si−O bonds in the tetrahedral SiO4 unit typically found in a zeolite. All the bond angles in the SiO4F- unit agree with those expected for a regular trigonal bipyramidal XY5 unit. The calculated structure is shown to reproduce accurately an averaged structural model determined by standard crystallographic methods. The approach we have developed in this work has general implications for the solution of complex local structure problems in solids.