An investigation into the Bronsted acidity of the perfluorinated alkoxy silanes {(F3C)3CO}3SiH and {(F6C5)3CO}2Si(Cl)H

The perfluorinated alkoxy silanes {(F3C)(3)CO}(3)SiH (1) and {(F5C6)(3)CO}(2)Si(Cl)H (2) were prepared and fully characterized. Despite the high calculated Bronsted acidities, all attempts to deprotonate 1 and 2 to give the conjugate silanide ions failed due to the exceptionally short and strong Si-H bonds. In the solid state, the Si-H units are not involved in any intermolecular interactions, but instead the crystal packing consists of exceptionally short and strong F...F interactions. The cohesive energies are entirely comprised of London dispersion interactions, similarly as in the crystal structures of noble gases.

Automated summary

The perfluorinated alkoxy silanes were synthesized and fully characterized. However, attempts to deprotonate them to form the conjugate silanide ions failed due to the exceptionally short and strong Si-H bonds. In the solid state, the Si-H units do not participate in any intermolecular interactions, and the crystal packing is dominated by exceptionally short and strong F...F interactions. The cohesive energies are solely attributed to London dispersion interactions, similar to noble gas crystal structures.