FORMATION OF MOLYBDENUM AND TUNGSTEN CATION PAIRS ON SILICA FROM CYCLOPENTADIENYLMOLYBDENUM DI-CARBONYL AND TRICARBONYL DIMER, CYCLOPENTADIENYLTUNGSTEN DI-CARBONYL AND TRICARBONYL DIMER, AND NTADIENYL)-1,1,2,2-TETRACARBONYLMOLYBDENUMTUNGSTEN

Cyclopentadienylmolybdenum di- and tricarbonyl dimer, cyclopentadienyl tungsten di- and tricubonyl dimer, and ntadienyl)-1,1,2,2-tetracarbony lmolybdenumtungsten was introduced to SiO2, and the resulting chemical ly adsorbed structures were studied using Fourier transform infrared s pectroscopy and temperature-programmed decomposition. The complexes re act with surface hydroxyls of the silica as evidenced by the attenuati on of the isolated silanol IR absorbance at 3742 cm-1 and the formatio n of cyclopentadiene. Changes in the carbonyl infrared bands during he ating and the temperature programmed decomposition results suggest tha t this exchange reaction yields discrete cation-cation pairs. Removal of the carbonyl ligands leads to Mo or W cations with an average oxida tion state of 4+.