Synthesis, characterization, crystal and molecular structure of diphenyloxophosphinoethylenediamines

Bis-, tris- and tetrakis(diphenyloxophosphino)ethylenediamine compounds can be synthesized starting with ethylenediamine and chlorodiphenylphosphine. Bis(diphenylphosphino)ethylenediamine and tris(diphenylphosphino)ethylenediamine are formed as intermediates and can be oxidized to the respective phosphine oxides by oxygen dissolved in the reaction solution, while tetrakis(diphenylphosphino)ethylenediamine is less liable to oxidation and its oxidation requires a stronger oxidizing agent such as hydrogen peroxide. All the three phosphine oxides and tetrakis(diphenylphosphino)ethylenediamine can be isolated as analytically pure solid materials and are fully characterized by elemental analysis, MS and NMR spectroscopies. The crystal and molecular structure of tris(diphenylphosphino)ethylenediamine was elucidated by single crystal X-ray diffraction analysis