Immobilization of platinum(ii) and palladium(ii) complexes on metal oxides by sol–gel processing and surface modification using bifunctional phosphine–phosphonateesters

Abstract

The bifunctional phosphine–phosphonate ester derivatives Ph₂P(CH₂)₃P(O)(OSiMe₃)₂ (L), (cis-Cl₂Pt[Ph₂P(CH₂)₃P(O)(OSiMe₃)₂]₂ (1), trans-Cl₂Pd[Ph₂P(C₆H₄)P(O)(OSiMe₃)₂]₂ (2) and trans-Cl₂Pd[Ph₂P(C₆H₄)P(O)(OEt)₂]₂ (3) were used to immobilize platinum(II) and palladium(II) complexes on metal oxide supports by three different routes: sol–gel incorporation of L in TiO₂ or ZrO₂ matrices followed by complexation with PtCl₂(PhCN)₂, direct sol–gel immobilization of 1 and 2, surface modification of TiO₂nanoparticles with 2 and 3. The hybrid solids were characterized by solid-state ³¹P MAS NMR spectroscopy, surface area measurements and chemical analysis; the advantages and disadvantages of the different routes were discussed. This study demonstrates that phosphonic esters can provide a valuable alternative to phosphonic acids for the preparation of functional organic–inorganic hybrids based on metal oxides.