Facile Phosphorus–Carbon Bond Formation using a Tungsten-Coordinated Phosphirenyl Cation

Reaction of K2[W­(CO)5] with Cl2PN-i-Pr2 in the presence of diphenylacetylene leads to the tungsten aminophosphirene complex [W­(CO)5{P­(N-i-Pr2)­C­(Ph)­C­(Ph)}] (1), which can be converted to the chlorophosphirene complex [W­(CO)5{P­(Cl)­C­(Ph)­C­(Ph)}] (2) by reaction with HCl. Chloride abstraction from 2 with excess AlCl3 leads to the tungsten-complexed phosphirenyl cation [W­(CO)5{PC­(Ph)­C­(Ph)}]­[AlCl4] (3). Compound 3 reacts with PPh3 to form a phosphoniophosphirene complex and undergoes electrophilic aromatic substitution with ferrocene to form a ferrocenylphosphirene complex. Chloride abstraction from 2 with silver triflate leads to a phosphirenyl triflate complex, which reacts with PPh3 and ferrocene in the same fashion as 3 but also reacts cleanly with a wider range of substrates, including phenylacetylene and allyltrimethylsilane, to form respectively a phenylalkynylphosphirene complex and an allylphosphirene complex.