Organic-inorganic hybrid materials incorporating phosphorus centres. Evidence for some factors controlling the accessibility of phosphorus centres

The accessibility of phosphorus centres incorporated into hybrid organic-in organic materials prepared from various phosphines bearing two or three hyd rolysable SiX3 groups has been investigated by using some classical reactio ns at phosphorus centres. Estimation of the yields of the reaction has been established by high power proton decoupling magic angle spinning (HPDEC MA S) solid state P-31 NMR spectroscopy. It was found that reagents such as H2 O2, S-8 as well as THF . BH3 and MeI can reach all the phosphorus centres w hatever the starting material. In contrast, remarkable differences of acces sibility of phosphorus centres in the studied solids were found for the mor e bulky reagent THF . W(CO)(5). From these results, it appears that the acc essibility of the phosphorus centres depends on the structure of the precur sor, the degree of condensation of the polysilsesquioxane network, and the specific surface area of the material.