Can 1,3-butadiene be catalytically hydrophosphinated in the presence of Cp2EuH? A DFT investigation.

The hydrophosphination reaction of 1,3-butadiene in the presence of Cp(2)EuH has been studied by DFT methods. It has been possible to show that such a reaction can be catalytically performed and that the active species is Cp(2)EuPH(2). The phosphido complex can be formed from the hydride either in a one step reaction (direct P-H activation in the presence of Cp(2)EuH) or in a two-step reaction (1,3-butadiene insertion into the Eu-H bond followed by a P-H activation). The latter has been calculated to be the preferred pathway. The catalytic cycle is predicted to be efficient since virtually no side reactions can occur. Three phospho-olefins can be formed: phospho-1-but-2-ene as the major product, and phospho-2-but-3-ene and phospho-1-but-3-ene as minor ones. These two products are derived from either a 1,4 insertion (former product) or a 1,2 insertion (phospho-2-but-3-ene). The phospho-1-but-3-ene comes from isomerization of the phosphoallyl (product of the 1,4 insertion).