Synthesis of monophasic hybrid organic-inorganic solids containing [eta(6)-(organosilyl)arene]chromium tricarbonyl moieties

Silica gel containing benzenechromium tricarbonyl units have been obtained from molecular organosilicon precursors. The hydrolytic sol-gel polymerization of [eta(6)-C6H5Si(OMe)(3)]Cr(CO)(3) (1), [eta(6)-1,4-C6H4RR']Cr(CO)(3) [R = R' = Si(OMe)(3) (2), R = R' = CH2Si(OMe)(3) (3), R = R' = CH2CH2Si(OMe)(3) (4)], {eta(6)-1,3,5-C6H3[Si(OMe)(3)](3)}Cr(CO)(3) (5), under nucleophilic catalysis by fluoride ion (NH4F), have led quantitatively to new monophasic hybrid organic-inoroanic silica gels. The derived xerogels X were characterized by FT IR, C-13 and Si-29 solid state CP MAS NMR spectroscopies. The silicon-carbon bond and the tricarbonylchromium ligand were retained within the gel. The major environment of the Si atoms corresponded to a T-2:CSi(OR)(OSi)(2) substructure for X2-X4, a T-3:CSi(OSi)3 one for X1 and a Ts:CSi(OR)(2)(OSi) in the case of X5. In most cases, these were amorphous materials that exhibited low specific surface areas (similar to 10 m(2) g(-1)). Upon heating the xerogels X1, X2, and X4 at 400 degrees C under an argon flow, weight losses corresponding to complete carbon monoxide elimination were obtained, leading to chromium in a low oxidation state within the solid.