Ab Initio Characterization of the Isomerism between the -2
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- 作者：Christopher J. Cramer ; Bradley A. Smith ; and William B. Tolman
- 刊名：Journal of the American Chemical Society
- 出版年：1996
- 出版时间：November 13, 1996
- 年：1996
- 卷：118
- 期：45
- 页码：11283 - 11287
- 全文大小：154K
- 年卷期：v.118,no.45(November 13, 1996)
- ISSN：1520-5126
文摘
The interconversion of model compounds{[(NH3)3Cu]2(
-
2:2-O2)}2+(1) and{[(NH3)3Cu]2(-O)2}2+(2) has been examined using multireference second-orderperturbation theory with an 8-electron/8-orbital activespace. At this level of theory, 1 and 2 areseparated by only 0.3 kcal/mol, and the barrier to isomerization ispredictedto be very low based on single-point energy calculations forintermediate structures. The flat nature of thepotentialenergy surface along the interconversion coordinate derives from abalancing of Coulomb forces and nondynamicelectron correlation. The latter effect depends critically on thesignificant energy change experienced by the13au
virtual orbital on passing from one isomer to the other. Inaddition, solvation electrostatics favor 2 over1.
-2:2-O2)}2+(1) and{[(NH3)3Cu]2(-O)2}2+(2) has been examined using multireference second-orderperturbation theory with an 8-electron/8-orbital activespace. At this level of theory, 1 and 2 areseparated by only 0.3 kcal/mol, and the barrier to isomerization ispredictedto be very low based on single-point energy calculations forintermediate structures. The flat nature of thepotentialenergy surface along the interconversion coordinate derives from abalancing of Coulomb forces and nondynamicelectron correlation. The latter effect depends critically on thesignificant energy change experienced by the13auvirtual orbital on passing from one isomer to the other. Inaddition, solvation electrostatics favor 2 over1.