A comparison of orbital interactions in the additions of phosphonyl and acyl radicals to double bonds†
Abstract
Calculation of the barriers for addition of the H2P(O)˙ and HC(
O)˙ radicals to
O)˙ radical this behaviour occurs because a secondary orbital interaction of the type π*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 σ*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.