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題 名 | Ab Initio Study of Various Structures of N埍=各種結構之N埍Ab Initio法理論研究 |
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作 者 | 孫光中; 陳成; | 書刊名 | 火藥技術 |
卷 期 | 13:1 1997.03[民86.03] |
頁 次 | 頁1-23 |
分類號 | 348.221 |
關鍵詞 | N埍; Ab initio; MP2/6-31G(d); HF/6-31G(d); |
語 文 | 英文(English) |
英文摘要 | For thirteen N�^isomers were fully optimized at HF/6-31G(d)//HF/6-31G(d) and MP2/6-31G(d)//MP2/6-31G(d) levels. These isomers are the nitrogen analogues of the following hydrogen carbon skeletons: 1,2-dihydropentalene, cyclooctatetraene (tub form), barrelene bicyclo [2.2.2] octa2, 5, 7-triene, bicyclo[4.2.0] octa-2, 4, 7-triene (C �� and C ) , tricyclo[3.3.0.0 �� ]-octa-3,7-diene, tetracyclo[4.2.0.0 ��.0 �� ] octa-7-ene, anti-tricyclo [4.2.0.0 ] octa-2,6-diene, syn-tricyclo [4.2.0.0 ] octa-2,6-diene, cuneane, octabisvalene, cyclooctatetraene (crown form) and cubane. They are of interest because there are the experimentally known (CH) �^ carbon structures, and the (CH) group is replaced by N atoms. There are twelve local minima were found on the energy hypersurface at HF/6-31(d)//basis set via vibrational frequency calculations at the same levels of theory. The effect of correlation on the various stationary point structures are examined use of MP2/6-31G(d)// calculations. These calculations indicated that only eleven N �^ isomers are stable except barrelene bicyclo[2.2.2] octa-2, 5, 7-triene(3) and cyclooctatetraene (12, crown form). These calculations indicate that, if there could be synthesized, the eleven N �^ isomers would be a series of highly energetic compounds. When these metastable isomer's dissociation to four N �� the energy releases for these reactions that are predicated from 247 (1) to 478 (13) kcal/mol (including zero-point energy corrected) at MP2/6-31G(d)// model. Comparisons of the lowest vibrational frequency both MP2/6-31G(d) // and HF/6-31G(d)// model showed that the N �^ cubane is the highest energetic rigidity material and is a stable molecule among these isomers. However, these calculations presented that the N �^ 1,2-dihydropentalene (1) with two planar five-membered rings is the most stable molecule among the thirteen structures and that the N �^ isomer (1) if it can be synthesized by experiment would easier than all the others. |
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