Ab initio study of structures of fluorocyclobutenes and MXY(M=Ca,Sr,Ba;X,Y=H,F,Cl,Br,I) molecules플루오로시클로부텐과 MXY (M=Ca,Sr,Ba ; X,Y =H,F,Cl,Br,I)분자 구조의 순이론적 연구

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Unusually large discrepancy exists between the reported value of the experimental geometries of hexafluorocyclobutene determined from microwave spectroscopy (MW) and those from electron diffraction (ED). In an effort to explain the origin of the difference, the geometries of cyclobutene, 1,2-difluorocyclobutene, 3,3,4,4 -tetrafluorocyclobutene, hexafluorocyclobutene and 1,2-dichloro-3,3,4,4 -tetrafluorocyclobutene are optimized by ab initio calculations at the HF, MP2 and CISD levels of theory, and further refined for the higher correlation effects through the use of model calculations of ethane,ethene, fluoroethane and fluoroethene. Comparison of the calculated results with available MW and ED parameters imply that MW geometrical parameters are probably more accurate for hexafluorocyclobutene than ED ones. The difficultly associated with vibrational corrections for hexafluorocyclobutene appears to be responsible for the unusual pattern of the difference between ED and MW structures. For hetero-substituted molecules MXY (M = Ca, Sr, Ba ; X, Y = H, F, Cl, Br, I), the equilibrium geometries of the ground states have been optimized at the HF, MP2, and CISD levels of the theory using effective core potentials and extended valence basis sets. The bondings, bending potentials and structures characteristic of hetero-substituted MXY molecules are presented in this paper. Core polarization (influence of the subvalence) and s-d hybridization (influence of the valence shell), to varying extents, control the bending in $MX_2$ and MXY systems. The bending potentials of MXY compounds, however, are relatively flatter than those expected from $MX_2$ and $MY_2$, leading to all linear forms of CaXY and linear SrFBr, SrFI, SrFAt, SrClBr, SrClI, and SrClAt of SrXY.BaXY are all in the bent forms but their bending potentials are very flat. Natural Atomic Orbital and Natural Population Analysis are suitable tools for explanation to this phenomena.
Advisors
Lee, Yoon-Supresearcher이윤섭researcher
Description
한국과학기술원 : 화학과,
Publisher
한국과학기술원
Issue Date
1996
Identifier
105606/325007 / 000943574
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 화학과, 1996.2, [ iii, 63 p. ]

Keywords

Ab initio; Fluorocyclobutenes; MXY(M=Ca,Sr,Ba; 순이론적 연구; MXY분자; 플루오로시클로부텐; X,Y=H,F,Cl,Br,I) Molecules

URI
http://hdl.handle.net/10203/32747
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=105606&flag=dissertation
Appears in Collection
CH-Theses_Master(석사논문)
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