CARBON-DIOXIDE AND NITROUS-OXIDE COMPLEXES OF CR(II) SUPPORTED ON SILICA

Three kinds of Cr(II) ions (A, B and C) are present on CO reduced CrO3/SiO2 samples, with decreasing coordinative unsaturation. Cr(A) and Cr(B) form linear adducts with the title molecules, whereas Cr(C) is inactive. It is probable that Cr(B) only forms monoligand complexes, and that Cr(A) may form two-ligand complexes: the presence of a second coordinative vacancy in Cr(A) is shown by the formation of dicarbonyls, Cr(A)(CO)2, and mixed carbonylic species, Cr(A)(CO)CO2. Nitrous oxide binds to surface Cr either end, giving rise to species clearly discernible from their IR spectra.