Silica-surface reorganization during organotin grafting evidenced by Sn-119 DNP SENS: a tandem reaction of gem-silanols and strained siloxane bridges - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Physical Chemistry Chemical Physics Année : 2014

Silica-surface reorganization during organotin grafting evidenced by Sn-119 DNP SENS: a tandem reaction of gem-silanols and strained siloxane bridges

Résumé

Grafting reactive molecular complexes on dehydroxylated amorphous silica is a strategy to develop "single-site" heterogeneous catalysts. In general, only the reactivity of isolated silanols is invoked for silica dehydroxylated at 700 degrees C ([SiO2-700]), though ca. 10% of the surface silanols are in fact geminal Q(2)-silanols. Here we report the reaction of allyltributylstannane with (SiO2-700] and find that the geminal Q(2)-silanols react to form products that would formally arise from vicinal Q(3)-silanols that are not present on (SiO2-700], indicating that a surface rearrangement occurs. The reorganization of the silica surface is unique to silica dehydroxylated at 700 degrees C or above. The findings were identified using Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) combined with DFT calculations.

Dates et versions

hal-01070828 , version 1 (02-10-2014)

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Matthew P Conley, Aaron J. Rossini, Aleix Comas-Vives, Maxence Valla, Gilles Casano, et al.. Silica-surface reorganization during organotin grafting evidenced by Sn-119 DNP SENS: a tandem reaction of gem-silanols and strained siloxane bridges. Physical Chemistry Chemical Physics, 2014, 16 (33), pp.17822-17827. ⟨10.1039/c4cp01973c⟩. ⟨hal-01070828⟩
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