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
Hauptverfasser: Nori-Shargh, Davood, Hassanzadeh, Neda, Kosari, Meisam, Rabieikarahroudi, Parvin, Yahyaei, Hooriye, Sharifi, Sasan
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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.
ISSN:0008-4042
1480-3291
DOI:10.1139/V10-022