Selective dimerization of Lewis-acid/base-stabilized phosphanylalanes

The reaction of [{(CO)(5)W}PRH(2)] (R = H, Ph) with H(3)Al⋅NR(3) (R = Et, Me) leads to the formation of four-membered heterocyclic compounds [({(CO)(5)W}P(H)AlH⋅NEt(3))(2)] and [({(CO)(5)W}PhPAlH⋅NMe(3))(2)]. Upon dissolving the solid compounds, fast equilibria between the isomers are observed on the NMR timescale. Further insight into the stability and reactivity of the isomers was gained by applying theoretical methods. DFT calculations predict that hydrogen elimination in the case of [({(CO)(5)W}PhPAlH⋅NMe(3))(2)] may be reversible.