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 iPr(2)Im (1,3-di-isopropyl-imidazolin-2-ylidene) has been reported. The dehydrogenation of R2PH affords diphosphines R2P-PR2. The reaction of iPr(2)Im with ArPH2 leads to the formation of NHC phosphinidene adducts iPr(2)Im = PAr 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.