Synthesis of Monophasic Hybrid Organic−Inorganic Solids Containing [η⁶-(Organosilyl)arene]chromium Tricarbonyl Moieties

Abstract

Silica gel containing benzenechromium tricarbonyl units have been obtained from molecular organosilicon precursors. The hydrolytic sol-gel polymerization of [η 6 -C 6 H 5 Si- 5), under nucleophilic catalysis by fluoride ion (NH 4 F), have led quantitatively to new monophasic hybrid organicinorganic silica gels. The derived xerogels X were characterized by FT IR, 13 C and 29 Si 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 (∼10 m 2 g -1 ). Upon heating the xerogels X1, X2, and X4 at 400 °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.

Ceramics and Nanostructures from Molecular Precursors

“…Figure 9 shows, for instance, the great difference in the solid obtained simply by changing the counterion used in nucleophilic catalysis; all other parameters were identical. [64,77] All these experiments are reproducible. However, the reproducibility in texture and polycondensation is obtained only when the experimental conditions (including the purity of chemicals) are carefully controlled.…”

“…As illustrated in Scheme 20 they behave quite differently. [64] Solid L' is hydrophilic and has a high specific surface area (550 m 2 g À1 ). The SIMS does not exhibit any fragments that derive from C 6 H 4 ; only SiOH fragments can be detected.…”

Nanoporous materials: a good opportunity for nanosciences

“…The reactivity of aromatic groups bound to silica matrix towards Cr(CO) 6 will be given as an example [52][53][54].…”

Keramiken und nanostrukturierte Materialien aus molekularen Vorstufen

“…So ist in Abbbildung 9 beispielswiese gezeigt, wie stark sich die erhaltenen Feststoffe unterscheiden, wenn nur das bei der nucleophilen Katalyse verwendete Gegenion ausgetauscht wird und alle anderen Parameter gleich bleiben. [64,77] Alle diese Experimente sind reproduzierbar. Die Texturen und Polykondensationen sind allerdings nur dann reproduzierbar, wenn die experimentellen Bedingungen sorgfältig eingehalten werden (dazu zählt auch die Reinheit der verwendeten Chemikalien).…”