Theoretical Chemistry and Biochemistry group, SRSMC, University of Lorraine, CNRS, BP 70239, 54506 Vandœuvre-lès-Nancy, Cedex, France.
Chemphyschem. 2012 Oct 8;13(14):3397-403. doi: 10.1002/cphc.201200135. Epub 2012 Jul 10.
We report a theoretical study on non-conventional structures of 1:1 complexes between carbon dioxide and carbonyl compounds. These structures have never been reported before but are relevant for understanding the solubility of carbonyl compounds in supercritical CO(2). The work is based on the results of ab initio calculations at the MP2 and CCSD(T) levels using aug-cc-pVDZ and aug-cc-pVTZ basis sets. Investigated systems include aldehydes, ketones and esters, together with some fluorinated derivatives. The results are interpreted in terms of natural bond orbital analyses. Harmonic vibrational frequency calculations have also been done in order to compare them with available experimental data. We show for the first time that complexes where CO(2) behaves globally as a Lewis base are stable in the case of ketones and esters, but not in the case of aldehydes, and their stability is similar to that of traditional complexes in which CO(2) behaves as a Lewis acid. This finding considerably modifies the concept of CO(2)-philicity and may have important ramifications in the development of green reactions in supercritical CO(2).
我们报告了二氧化碳与羰基化合物 1:1 复合物的非常规结构的理论研究。这些结构以前从未被报道过，但对于理解羰基化合物在超临界 CO2 中的溶解度很重要。这项工作是基于 MP2 和 CCSD(T)水平的从头算计算结果，使用 aug-cc-pVDZ 和 aug-cc-pVTZ 基组。研究的系统包括醛、酮和酯，以及一些氟化衍生物。结果根据自然键轨道分析进行了解释。还进行了谐波振动频率计算，以便将其与可用的实验数据进行比较。我们首次表明，在酮和酯的情况下，CO2 整体表现为路易斯碱的复合物是稳定的，但在醛的情况下则不稳定，其稳定性与 CO2 表现为路易斯酸的传统复合物相似。这一发现极大地改变了 CO2-亲合性的概念，并可能对超临界 CO2 中绿色反应的发展产生重要影响。
