Preparation and characterization of organic-inorganic hybrid materials incorporating diphosphino moieties.: Study of the accessibility of the phosphorus atoms included into the material

The hydrolysis-polycondensation by the sol-gel process of the aromatic diphosphines (X3SiC6H4)(2)PC6H4P(C6H4SiX3)(2), which are rigid molecules bearing four hydrolysable SiX3 groups (X = OPr, H), leads to new organic-inorganic hybrid materials, characterized by solid state C-13, Si-29, and P-31 NMR spectroscopies. The accessibility of the phosphorus centres incorporated into the xerogel obtained from the diphosphine with X = (OPr)-Pr-i has been studied. All the phosphorus atoms reacted quantitatively with H2O2, S-8, and CH3I but only 20% with the more bulky reagent W(CO)(5),THF. This result is explained by the rigidity of the inorganic network resulting from the high number of hydrolysable Si-OPr groups in the precursor.