Gels by polycondensation of tetraethoxysilane and [Co(CO)3L]2 or Rh(CO)ClL2 (L=Ph2PCH2CH2Si(OEt)3) : interrelation between metal complex concentration and specific surface area

Abstract

Co-condensation of tetraethoxysilane (TEOS)and [Co(CO)3L]2 or Rh(CO)ClL2 (L=Ph2PCH2CH2Si(OEt)3) in different molar ratios has been studied in order to elucidate the influence of the metal complex concentration on the specific surface area of the obtained gels. Because the metal complex moieties are not decomposed and maximum surface areas are obtained, H3PO4 is superior to other acids as a catalyst for the condensation reaction. Elemental analyses show that no metal is lost during condensation. With increasing metal concentration the specific surface area of the polycondensates decreases rapidly: it drops to half its original value, if about 5 mol% metal complex is co-condensed with TEOS.