Ab initio studies of ether-carbene ylides

COMP 198

Jean M. Standard, standard@ilstu.edu and Ryan D. Quinn. Department of Chemistry, Illinois State University, Campus Box 4160, Normal, IL 61790-4160
Oxonium ylides are formed from the interaction of a singlet carbene with an oxygen-containing molecule. The simplest oxonium ylide, H2O-CH2, has previously been characterized as a weakly bound complex with a long C-O bond distance of about 1.8 and a binding energy of around 6 kcal/mol. In this work, the structure and bonding of oxonium ylides formed by the interaction of ethers with the singlet carbenes methylene and carbomethoxycarbene have been investigated using ab initio methods at the MP2 level of theory. The ether-methylene ylides are characterized by C-O bond distances that are longer than typical single bonds, relatively low charge transfer, and low binding energies. The ether-carbomethoxycarbene ylides, on the other hand, are characterized by C-O bond distances that are comparable to typical single bonds, higher charge transfer, and larger binding energies. The character of the bonding for the ether-methylene and ether-carbomethoxycarbene ylides has been analyzed using Natural Bond Orbital and Natural Resonance Theory methods, and differences in bonding have been attributed in part to the ability of singlet carbomethoxycarbene to better delocalize the charge transferred from the ether to the carbene.

Poster Session
6:00 PM-8:00 PM, Tuesday, August 18, 2009 Walter E. Washington Convention Center -- Ballroom A, Poster

Division of Computers in Chemistry

The 238th ACS National Meeting, Washington, DC, August 16-20, 2009