Dissertation > Excellent graduate degree dissertation topics show

Theoretical study of new compounds containing the planar four - coordinate carbon

Author: SunWenXiu
Tutor: ZhangCongJie
School: Shaanxi Normal University
Course: Physical and chemical
Keywords: Density functional theory (DFT) Planar tetracoordinate carbon (ptC) Quasi ptC Boron compounds C9B2H6 For C3B2 nH4 of the band structure The C3B2 n of the tubular structure The boron carbon nanotubes (m, 0, i)
CLC: O641.12
Type: Master's thesis
Year: 2008
Downloads: 56
Quote: 0
Read: Download Dissertation

Abstract


In this thesis using density functional theory (DFT), studied four categories contains planar tetracoordinate carbon (ptC) compound: the contains a ptC C 9 B 2 H 6 , contain multiple ptC of strip compounds (of C 3 B in 2 ) n H 4 (n = 2-6), to contain multiple of quasi ptC the tubular compounds (of C 3 B 2 ) n (n = 4-8), and contains plurality of quasi ptC of zigzag boron carbon nanotubes (m, 0, i) (m = 6,8,10 and 12; i = 1-4) of the structural stability and bonding properties. The main contents and conclusions are summarized as follows: 1. The B3LYP/6-311 G ** level, a new the two boron organic compounds C 9 contains a ptC B 2 H 6 structure, stability, and vibrational frequencies. The results show that: the C 9 B 2 H 6 the stability of the structure and the location of the two boron atoms have a great relationship, boron atoms given σ electrons from and to accept the role of the π-electron. C 9 B 2 H 6 15 isomers, the most stable structure with C 2v symmetry of isomers (1,5), the isomers of (1,5), the two boron atoms with a six-membered ring adjacent and ptC. Moreover, the the occupied π rail isomer (1,5) having a 10 π-electron meet 4n 2 rule. Moreover, the calculated nucleus independent chemical shifts (NICS) value isomers (1,5) aromatic the in C 9 B 2 H 6 < / sub> of the two three-membered ring instead of two six-membered ring. 2. The most stable structure H 2 C 2 CB 2 H 2 as the basic structure of the primitive, the design of two contains ptC the ribbon compounds (C 3 B 2 ) n H 4 (n = 2-6) and tubular compounds contain quasi ptC (C 3 B 2 ) n (n = 4-8). The B3LYP/6-311 G ** level, research ribbon compounds the (C 3 B 2 ) n H 4 (n = 2-6) of the structure, stability, aggregation rules and the vibration frequency. The results show that: (C 3 B 2 ) n H 4 (n = 2-6) is the most stable The structure is based on H 2 (C 2 CB 2 ) n H 2 arrangement arrangement of, namely C the 2 CB 2 unit arranged in the same direction. Calculated NICS values ??show that the three-membered ring aromatic six-membered rings have an anti-aromaticity. Most stable isomer H 2 (C 2 CB 2 ) n H 2 (n = 2-6) of the electronic spectra of the diagram illustrates the first electronic excitation energy has a linear relationship with the n. By C 2 CB 2 unit formed tubular compounds (C 3 B 2 ) n (n = 4-8) the structure and stability of the study show that: tubular compounds (C 3 B 2 ) n (n = 4-8) are stable structures, respectively, contain 4, 5, 6, 7 and 8, a quasi-PTC, the HOMO-LUMO energy gap exhibit parity alternately characterized. 3. Four structural matrix containing the different layers of PTC (N1 and N2, and N3 and N4), designed four new zigzag boron nanotubes includes a plurality of quasi ptC (m, 0, i) (m = 6, 8, 10 and 12; i = 1-4), and DFT methods to study their structure, stability and bonding properties. The results show that: C 2 CB 2 unit structure arranged in the same direction (ie C nv symmetry structure) for the most stable structure type. Moreover, with the increase of the of boron carbon nanotube diameter and tube length, the value of the energy gap between the HOMO-LUMO system monotonically decreasing. When the the boron carbon nanotubes tube long is long enough, the system exhibits metallic characteristics. The size of the pores of the tube surface is different for the different series of boron nanotubes, i.e. boron nanotubes (m, 0, i) (i = 1-4), when i is changed by 1 to 4 hours, the boron carbon atoms are respectively formed of one, two, three, and four kinds of ten yuan ring cavities, the size of the pores in 2.9 × 5.3 (?) to 2 3.8 × 6. 0 (?) 2 between. This indicates that the relatively large atoms or small molecules more easily through the 10-membered ring hole into the tube, so the boron carbon nanotubes is expected to become a new functional materials.

Related Dissertations

  1. Study on the Structures and Properties of Quercetin and Some Other Flavonoids,O621.2
  2. The Density Functional Study on Properties of Linquist-, Stranberg- and Keggin-Polyoxometalate Derivatives,O611.3
  3. First-Principles Research on Bulk Doping and Surface Adsorption of TiO2,TB39
  4. Theoretical Study on the Mechanism for Small Molecule Adsorption on the Si(111)-7×7 Surface,O641.1
  5. A Study for Structure and Properties of OsnN0, ± （n=1-6） Clusters,O641.1
  6. A Density Functional Theory Study for Wn C0,± （n=1-6） Clusters,O641.1
  7. Theoretical Study on Magnetic Properties of the 3d-Transition-metal-substituted Polyoxometalates Using the DFT-BS Method,O641.4
  8. Doped graphene and its electronic structure Theoretical Study,O613.71
  9. Theoretical Studies of the Chemical Modification and Electronic Properties for Nanotubes Materials,TB383.1
  10. Experimental, QM, and MD Studies on Reversed Micelles and Energetic Systems,TQ423
  11. The Research on Intermediate Phase Hydrides and the Behavior of Helium Atoms in LaNi5-based Hydrogen Storage Material,O482
  12. The Experimental and Theoretical Studies of Raman Spectra of 2,2’-bipy in Acidic Solution and 2,2’-bipy on Gold,O626
  13. Adamantane derivatives and tetrahedral alkyl structure and properties of high energy quantum chemical study,O621.13
  14. Amino acid dipeptide crystal structure and theoretical study of the vibrational spectra,O629.7
  15. The Preparation of Noble Metal Nanoparticles and the Application in Raman Spectroscopy,O611.3
  16. Impurity gases in the adsorption behavior of palladium alloy,O561
  17. LaNi_ (4.5) Al_ (0.5) H_x crystal microscopic configuration of the hydrogen,O561.1
  18. A Time Dependent Density Functional Theoretical Studies of the Ruthenium(Ⅱ) Complexes,O641.4
  19. Quantum Chemistry Calculation on Battery Material of LiFePO4 System,TM912
  20. DFT Study on Mechanism of Several Transition Metal-Catalyzed Asymmetric Reaction,O643.32

CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Structural Chemistry > Chemical bond theory > Quantum mechanical theory of chemical bonds
© 2012 www.DissertationTopic.Net  Mobile