Configuration interaction and density functional study of the influence of lithium cation complexation on vertical and adiabatic excitation energies of enones
Configuration interaction and density functional study of the influence of lithium cation complexation on vertical and adiabatic excitation energies of enones
复制标题
锂阳离子络合对烯酮垂直和绝热激发能影响的构型相互作用和密度泛函研究
DOI：
--
复制
发表时间：
2001
影响因子：
3
通讯作者：
Jayaraman Chandrasekhar
中科院分区：
文献类型：
--
作者：
R. B. Sunoj;P. Lakshminarasimhan;Vaidhyanathan Ramamurthy;Jayaraman Chandrasekhar;Jayaraman Chandrasekhar
用从头算和密度泛函方法研究了典型的环烯酮（环戊烯酮和环己烯酮）在锂离子配位作用下激发态能量的变化。通过在CIS和CIS（D）水平上使用6 - 31+G（d）基进行的构型相互作用计算，获得了垂直三重态能量的定量估计。双微扰修正对n-π* 和π-π* 三重态的相对能量有显著影响。在Cl和CIS（D）水平下，预测锂络合使n-π* 三重态的能量比π-π* 三重态高得多。在CIS（D）水平上获得的趋势使用B3 LYP/6 - 31+G（d）计算再现。通过在B3 LYP水平上对三重态进行几何优化，计算了分子的绝热激发能。虽然对于母体烯酮，几何优化的n-π* 和π-π* 三重态之间的分离非常小，但在锂络合物中明显有利于π-π* 三重态。这些结果表明，通过阳离子络合反应逆转的反应性光激发态的烯酮的可能性。这些结论为在阳离子交换沸石中观察到的烯酮产物分布的有趣变化提供了依据。John Wiley & Sons，Inc. J Comput Chem 22：1598-1604，2001
The changes in the excited state energies of representative cyclic enones (cyclopentenone and cyclohexenone) induced by lithium ion coordination have been examined using ab initio and DFT methods. Quantitative estimates of the vertical triplet state energies were obtained using configuration interaction calculations at the CIS and CIS(D) levels with the 6‐31+G(d) basis. Inclusion of perturbative doubles corrections has a marked effect on the relative energies of the n–π* and π–π* triplet states. At both CI and CIS(D) levels, lithium complexation is predicted to raise the energy of the n–π* triplet state much more than the π–π* triplet. The trends obtained at the CIS(D) level are reproduced using B3LYP/6‐31+G(d) calculations. Adiabatic excitation energies were also computed by carrying out geometry optimization of the triplet states at the B3LYP level. While the separation between the geometry optimized n–π* and π–π* triplet states is very small for the parent enones, the π–π* triplet is clearly favored in the lithium complexes. These results suggest the possibility of reversing the reactive photoexcited state in enones through cation complexation. The conclusions provide a rationale for interesting variations in product distributions observed for enones in cation exchanged zeolites. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1598–1604, 2001