Dissertation
Dissertation > Mathematical sciences and chemical > Chemistry > Organic Chemistry > Organic Chemistry general issues > Theory of organic chemistry,physical organic chemistry > Organic Chemistry Structure Theory

Density Functional Theory Studies on the Electronic Structure and Characteristics of Boranes and Their Derivatives

Author LiuZuZuo
Tutor YiXiangHui;HouRuoBing
School Guangxi Normal University
Course Inorganic Chemistry
Keywords Borane Wiberg bond order Multi-center bond Molecular orbital Density functional theory Molecular stability Vertical ionization energy Vertical electron affinity
CLC O621.13
Type Master's thesis
Year 2006
Downloads 144
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Since 1912 the German Alfred Stock Synthesis B 2 H 6 , B 4 H 10 , B 5 H 9 , B 6 H 10 and a series of borane has been a great deal about borane and its derivatives have been synthesized out. Borane as electron-deficient molecules covalently its special chemical workers caused a lot of interest, and thus the emergence of a large number of borane and its derivatives on the geometry and bonding properties of the research results, but the use of key system-level theoretical study borane and its derivatives in the form of a special bond has not been reported in the literature. In this paper, B 2 H 6 , B 2 H 5 Br, C 2 H 10 B 2 , C 4 H 14 B 2 , B 2 H 7 N, C 2 H 11 B 2 N, B 3 H 7 CO, B 3 H 7 NCS-, B 3 H 7 NCSe-, B 3 H 7 NCBH 3 -, B 3 H 6 Cl 2 -, B 5 H 9 , B 6 H 8 < / sub> S 2 CH 2 , B 8 H 12 , B 10 H 14 , B 4 H 10 , B 9 H 15 , B < sub> 10 H 16 , B4 H 6 C 2 H 2 and other molecules using Gaussian03 programs and B3LYP/6-31 G (d, p) method to optimize the structure of them, in obtaining a good agreement with the experimental results of the molecular structure, the calculation of all of its covalent bond order Wiberg , hoping to in-depth analysis and understanding of borane and its derivatives bonding mechanism between atoms and molecules stability; Meanwhile, to further understand the borane and derivatives related chemical properties, the use of the experimental method calibrated B3LYP/DZP were calculated B 2 H 6 , B 4 H 10 , B 5 H 9 , B 8 H 12 , B 9 H 15 , B 10 H 16 , B 2 H 4 C 2 H 6 , B 2 H 2 C 4 H 12 , B 2 H 5 NH 2 , B 2 H 5 NC 2 H 6 , B 3 H 7 CO molecule and part of the vertical ionization energies of molecules vertical electron affinity. All calculation results show that: (1) using B3LYP/6-31 G (d, p) method to calculate all these molecules covalently Wiberg bond order is significantly larger than on the number of valence electrons in the molecule resulting total classic valence bond level; (2) of a bonding molecular orbital analysis revealed the existence of these molecules in the fact that a variety of multi-center bond; (3) borane derivatives tend to form cage-like molecular structure of the root cause of This structure allows the electron-deficient atoms are formed to the center as much as covalent bond; (4) multi-center bond can be formed between the bonded atoms produce larger orbital overlap, thus the molecule has a larger level Wiberg bond and the larger the mean molecular bond order has good stability, which may include borane and its derivatives, including electron-deficient molecules to stabilize the root causes exist; (5) by a calibrated B3LYP/DZP experiment calculated molecular vertical portion obtained the value of the ionization energy between 9.14 ~ 11.24eV, suggesting that these molecules are not borane derivatives lose electrons easily, reducing weak. The calculated and experimental photoelectron spectroscopy of these molecules are very close, so as borane derivatives and high-energy photoelectron spectroscopy experiments provide reliable theoretical support. While some elements of the vertical electron affinity between the 0.08 ~ 2.18eV, indicating that these molecules are relatively easy to obtain electron, which is its lack of electronic characteristics of specific performance. Therefore, it is speculated that when borane and derivatives thereof combined with a Lewis base, should exhibit a very active chemical nature, which is consistent with the experimental results.

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