The reductive P–P coupling of primary and secondary phosphines mediated by N-heterocyclic carbenes†
The dehydrogenative coupling of primary and secondary phosphines with the N-heterocyclic carbene iPr2Im (1,3-di-isopropyl-imidazolin-2-ylidene) has been reported. The dehydrogenation of R2PH affords diphosphines R2P–PR2. The reaction of iPr2Im with ArPH2 leads to the formation of NHC phosphinidene adducts iPr2ImPAr and cyclic oligophosphines P4Ar4, P5Ar5 and P6Ar6, depending on the stoichiometry used. The NHC acts in these reactions as a phosphine activator and hydrogen acceptor.