The reductive P–P coupling of primary and secondary phosphines mediated by N-heterocyclic carbenes

Abstract

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.