Reaction of three-coordinate phosphorus compounds with organophosphorus pseudohalogens. Part 4. The mechanism of interaction between bis(phosphinoyl)diselenides [(RRP)-R-1-P-2(O)Se](2) with three-coordinate phosphorus compounds

The reaction of bis(phosphinoyl) diselenides (RRP)-R-1-P-2(O)Se-SeP(O)(RR2) -R-1 1 with P(III) compounds has been investigated and its mechanistic feat ures have been elucidated by variable temperature P-31 NMR spectroscopy. Th ese studies show that in most cases phosphonium intermediates [drop P(O)-Se(-)P(-)drop O--P(Se)drop] 7, 13 and [drop P(Se)-O-P(-)drop O-- P(Se)drop] 10, 16 are involved. In the case when ligands on P(III) increase the stabil ity of the five-coordinate structure, a phosphorane intermediate is observe d. In the isomerization 7 --> 10 and 13 --> 16 the pathway of decomposition (deselenization, deoxygenation or dealkylation) to give stable end product s is influenced by electronic and steric factors.