Electrophilic terminal phosphinidene complexes [Ar-Ar-P-W(CO)5 ] (Ar-Ar: biaryl or an analogue thereof) undergo a spontaneous insertion of the phosphorus atom into the vicinal CH bonds to give annelated phospholes. Twelve examples are described, including biphenyl, thienyl, pyrrolyl, and benzofuryl groups as biaryl moieties. The activation energy of the insertion reaction is quite low (about 2 kcal mol(-1) ).

Electrophilic terminal phosphinidene complexes [Ar‐Ar‐P‐W(CO)5] (Ar‐Ar: biaryl or an analogue thereof) undergo a spontaneous insertion of the phosphorus atom into the vicinal CH bonds to give annelated phospholes. Twelve examples are described, including biphenyl, thienyl, pyrrolyl, and benzofuryl groups as biaryl moieties. The activation energy of the insertion reaction is quite low (about 2 kcal mol−1).

Electrophilic terminal phosphinidene complexes [R1P-W­(CO)5] bearing 2-alkynylphenyl R1 substituents undergo a spontaneous cyclization to give intermediate five-membered species which are able to perform an electrophilic substitution reaction with toluene and mesitylene. An intramolecular version of this reaction is possible with appropriate R substituents on the CC triple bond.