آمار
| تعداد نشریات | 50 |
| تعداد شمارهها | 2,232 |
| تعداد مقالات | 20,475 |
| تعداد مشاهده مقاله | 25,238,707 |
| تعداد دریافت فایل اصل مقاله | 22,874,752 |
Ab Initio Study of Conformational and Configurational Properties of 1, 3- Diazacyclohepta-1, 2-diene and 1, 3-Diazacycloocta-1, 2-diene | ||
| Journal of Physical & Theoretical Chemistry | ||
| مقاله 2، دوره 1، شماره 1، مرداد 2004، صفحه 9-13 اصل مقاله (59.22 K) | ||
| نوع مقاله: Research Paper | ||
| نویسندگان | ||
| Issa Yavari* ؛ Vahideh Hadigheh-Rezvan* ؛ Mohsen Dadgar* | ||
| Not mentioned | ||
| چکیده | ||
| Ab initio calculations at HF/6-31G* level of theory for geometry optimization and MP2/6- 31G*//HF/6-31G* for a single point total energy calculation are reported for the important energy-minimum conformations and transition-state geometries of 1, 3-diazacyclohepta-1, 2- diene (2) and 1, 3-diazacycloocta-1, 2-diene (3). The C2 symmetric twist-chair (2-TC) conformation of 2 is calculated to be 7.4 kJ mol-1 more stable than the twist-boat (2-TB, C2) conformer. Interconversion of 2-TC and 2-TB conformations takes place by a relatively highenergy (58.2 kJ mol-1) transition state. The unsymmetrical chair (3-C) conformation of 3 is calculated to be 6.6 kJ mol-1 more stable than the C2 symmetric twist-boat (3-TB) form. The transition state linking 3-C and 3-TB conformations is 40 kJ mol-1 above 3-C. Racemization of 2-TC and 3-C conformations occures by cis-rotation and requires 77.9 and 83.5 kJ mol-1, respectively. | ||
| کلیدواژهها | ||
| Cyclic carbodiimides؛ Conformational analysis؛ Ab initio calculations؛ Chiral stability؛ Stereochemistry | ||
|
آمار تعداد مشاهده مقاله: 583 تعداد دریافت فایل اصل مقاله: 274 |
||
