Secondary phosphirane complexes isomerize above 100 °C to give the corresponding terminal phosphinidene complexes, which can be trapped by alkenes and alkynes. This reaction is a rare instance of the isomerization of a P^III derivative into a P^I derivative. It appears to mimic the reductive elimination of alkanes from transition-alkylmetal hydrides.

Secondary phosphirane complexes isomerize above 100 °C to give the corresponding terminal phosphinidene complexes, which can be trapped by alkenes and alkynes. This reaction is a rare instance of the isomerization of a P^III derivative into a P^I derivative. It appears to mimic the reductive elimination of alkanes from transition-alkylmetal hydrides.

The reactions of BX₃ (X = Cl, Br) with 7-R-7-phosphanorbornadiene–M(CO)₅ (M = Mo, W) complexes (1) yields products 2 and 4 in which the RP–M(CO)₅ unit is inserted into one of the carboxyl units of the phthalic derivative as a result of the collapse of the bridge. When X = Br, 4 cyclizes to give new six-membered heterocycles 5 with quasiplanar structures. When treated by an excess of BBr₃, heterocycles 5 undergo ring contraction to afford five-membered oxocyclic products 6.