ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
High-level ab initio calculations have been made for fluoromethylamine to study structural and energetic effects of the relative orientation of the N lone pair to the C—F bond. The anti-conformer (N lone pair anti-planar to the C—F bond) corresponds to the global energy minimum. It has the longest C—F distance, the shortest C—N distance, and is 7.5 kcal·mol-1 more stable than the related perpendicular conformation (lone pair perpendicular to the C—F bond). The syn-conformation also shows hallmarks of the anomeric effect: long C—F bond, short C—N bond, and energetic stability when allowance is made for the two pairs of eclipsed hydrogens. The transition state for N inversion is close to the syn-structure; rotation about the C—N bond is strongly coupled with this inversion process. Small bond distance changes of ca. 0.02 Å between parallel and perpendicular conformations are associated with dissociation energy differences of ca. 30 kcal·mol-1. Various criteria for assessing the strength of the anomeric effect are discussed.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19900730702
