Stereoelectronic interaction effects on the conformational properties of 5-methyl-5-aza-1,3-dithiacyclohexane and its analogous containing N, P, O, and Se atoms A hybrid density functional theory (DFT), ab initio study, and natural bond orbital (NBO) analysis
Natural bond orbital (NBO) analysis, hybrid density functional theory (hybrid DFT: B3LYP/6-311+G**//B3LYP/6-311+G**), and ab initio molecular orbital (MO: MP2/6-311+G**//B3LYP/6-311+G**) based methods were used to study the electronic delocalization energy (DE), dipole-dipole interactions, and steri...
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Veröffentlicht in: | Canadian journal of chemistry 2010-07, Vol.88 (7), p.579-587 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Natural bond orbital (NBO) analysis, hybrid density functional theory (hybrid DFT: B3LYP/6-311+G**//B3LYP/6-311+G**), and ab initio molecular orbital (MO: MP2/6-311+G**//B3LYP/6-311+G**) based methods were used to study the electronic delocalization energy (DE), dipole-dipole interactions, and steric repulsions on the conformational properties of 5-methyl-5-aza-1,3-dioxacyclohexane (
1
) (-phospha- (
2
), -arsena- (
3
)), 5-methyl-5-aza-1,3-dithiacyclohexane (
4
) (-phospha- (
5
), -arsena- (
6
)), and 5-methyl-5-aza-1,3-diselenacyclohexane (
7
) (-phospha- (
8
), -arsena- (
9
)). The MP2/6-311+G**//B3LYP/6-311+G** and B3LYP/6-311+G**//B3LYP/6-311+G** results revealed that the axial stereoisomers of compounds
1
-
9
are more stable than their equatorial stereoisomers. In this regard, the obtained results showed an egregious axial preference for compounds
1
,
4
, and
7
. Importantly, the results showed that the energy differences between the axial and equatorial stereoisomers decrease from compounds
1
→
3
,
4
→
6
, and also,
7
→
9
. The NBO analysis of donor-acceptor interactions revealed that the calculated DE for compounds
1
-
3
are -21.50, -7.84, and -4.38 kcal mol
-1
, respectively. The decrease of the calculated DE values from compound
1
to compound
3
could reasonably explain the decrease of the energy differences between the axial and equatorial stereoisomers from compound
1
to compound
3
. The correlation between the DE, dipole-dipole interactions, structural parameters, and conformational behaviors of compounds
1
-
9
has been investigated. |
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ISSN: | 0008-4042 1480-3291 |
DOI: | 10.1139/V10-022 |