Chromium (iii)-bis(iminophosphoranyl)methanido complexes: synthesis, X-ray crystal structures and catalyticethylene oligomerization

Abstract

Bis(aminophoshonium) salts derived from bis(diphenylphosphino)methane were prepared and triply deprotonated with potassium hexamethyldisilazane to yield the corresponding bis(iminophosphoranyl)methanides, which were then subjected to coordination with Cr^IIICl₃(THF)₃. Binuclear complexes of type [(HC(PPh₂NR)₂Cr(μ-Cl)(Cl))₂] (R = iPr, tBu) with an octahedral coordination geometry and a long C–Cr bond were obtained and structurally characterized. In the case of R = o-MeO-C₆H₄, a monomeric species featuring no C–Cr bond is observed. Preliminary evaluation of catalytic activities of these complexes in ethylene oligomerization and polymerization is reported.