Krenske Elizabeth H, Schiesser Carl H
Australian Research Council Centre of Excellence for Free Radical Chemistry and Biotechnology, Australia.
Org Biomol Chem. 2008 Mar 7;6(5):854-9. doi: 10.1039/b714597g. Epub 2008 Jan 14.
Calculation of the barriers for addition of the H2P(=O) and HC(=O) radicals to alkenes, at the CCSD(T)/aug-cc-pVDZ//BHandHLYP/6-311G** level, indicates that both radicals display ambiphilic behaviour. For the HC(=O) radical this behaviour occurs because a secondary orbital interaction of the type pi*(C=O)<--HOMO acts in conjunction with the primary SOMO<--HOMO interaction to balance the SOMO-->LUMO interaction. For the H2P(=O) radical, on the other hand, the much higher-lying LUMO (the sigma*P-O orbital) allows for only minimal secondary interaction, and this radical's ambiphilic behaviour is therefore reflective of a balance between SOMO-->LUMO and SOMO<--HOMO interactions.
在CCSD(T)/aug-cc-pVDZ//BHandHLYP/6-311G*水平下，对H2P(=O)和HC(=O)自由基加成到烯烃上的势垒计算表明，这两种自由基均表现出双亲性。对于HC(=O)自由基，这种行为的发生是因为π(C=O)<--HOMO类型的二级轨道相互作用与主要的SOMO<--HOMO相互作用共同作用，以平衡SOMO-->LUMO相互作用。另一方面，对于H2P(=O)自由基，其能量高得多的LUMO（σ*P-O轨道）仅允许最小的二级相互作用，因此该自由基的双亲性行为反映了SOMO-->LUMO和SOMO<--HOMO相互作用之间的平衡。
