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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. November 2003, Volume 2, Number 11, 723-731 |
Ab initio and Density Functional Studies on Cyclopropanone
Complexes with HF and HCl
Nobuaki Tanaka, Yoshitaka Urashima, Hiromasa Nishikiori, and Tsuneo Fujii
Internet Electron. J. Mol. Des. 2003, 2, 723-731
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Abstract:
Hydrogen bonding is an active topic of considerable interest.
Hydrogen bonds play an important role in reactivity and
chemical properties. Cyclopropanone possesses two possible
sites for the hydrogen-bond formation, that is, a carbonyl group
and a pseudo π C-C bond. How does the carbonyl substitution of
cyclopropane affect the complex formation? The MP2 and
B3LYP calculations are carried out for the geometry
optimization and following frequency analysis of
cyclopropanone complexes with HF and HCl. The
cyclopropane-hydrogen halide complexes are also studied for comparison. Two
stable conformers have been found: (I) the hydrogen-bond
complex with a C=O···HX (X = F, Cl) interaction and (II)
the C2v complex where a HX molecule interacts perpendicularly with a
C-C bond of cyclopropanone. The complex I is calculated to be
more stable than the complex II. In complex I contacting H-X
and C=O bonds are lengthened. In complex II a contacting H-X
bond is lengthened while a C=O bond is shortened. Natural bond
orbital analysis revealed intermolecular charge transfers occur
followed by intramolecular charge rearrangement. Large
contributions from the nO to the σ*H-X in complex I and from the
contacting σC-C to the σ*H-X in complex II are found.
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