کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5281927 | 1385681 | 2008 | 6 صفحه PDF | دانلود رایگان |
Tria-, penta-, hepta- and nonafulvenes (1-4) have been studied theoretically at the MP2 ab initio level of theory. For the global minimum structures, the occupation of the bonding ÏCC orbital of the exocyclic CC double bond, obtained by NBO analysis, quantitatively proves Ï-electron delocalization which can reveal partial 2-, 6- and 10-Ï-electron aromaticity, and 4-, 8- and 12-Ï-electron antiaromaticity of the ring moieties. Beside the corresponding occupation number, this conjugation was quantified by the length of the exocyclic CC double bond whilst the (anti)aromaticity of the ring moieties of 1-4 was visualized and quantified by through space NMR shielding surfaces (TSNMRS).
Spatial magnetic properties (TSNMRS) prove tria- and pentafulvenes to attain negligibly small partial aromaticity via conjugation with the exocyclic CC double bond but heptafulvene to be slightly antiaromatic.
Journal: Tetrahedron Letters - Volume 49, Issue 17, 21 April 2008, Pages 2776-2781