ORGN 451 |
| The conformations of thioformic anhydride have been studied at the HF and MP2 levels with the Gaussian 98 program. The optimized geometries, relative free energies, dipole moments and free-energy barriers were obtained for the EZ, EE, and ZZ conformations and their corresponding transition states at various levels of theory. At the MP2/6-311++G(2d,2p) level, the EE conformation is higher in free energy relative to the most stable ( EZ ) conformation by 1.02 kcal/mol. Both the EZ and the EE conformations are nearly planar. A third conformer, ZZ, has optimized OCSC dihedral angles of 9.6 degrees and a relative free energy of 3.6 kcal/mol. The free-energy barriers leading to topomerization of the EZ conformation were 6.7 and 8.6 kcal/mol, depending on the pathway. The dipole moments of the EE, EZ and ZZ conformations were 2.16, 2.90, and 4.14 D, respectively. |
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New Reactions, Methodology, Total Synthesis, Physical Organic Chemistry
8:00 PM-10:00 PM, Tuesday, 15 March 2005 Convention Center -- Sails Pavilion, Poster
Division of Organic Chemistry |