What can tell the quantum chemical topology on carbon–astatine bonds?

The nature of carbon–astatine bonds involved in some model species that mimic211At-labelled biomolecules, was investigated by means of ELF and QTAIM analyses in a context of two-component relativistic computations. The nature of the bonded carbon atom proved to be decisive. When At is bonded to an ethynyl group, some charge delocalisation with the vicinal triple C–C bond strengthens the At–C bond and gives it a multiple bond character. However, At displays also a large positive charge which may alter thein vivostability of such At–C bonds. In the case of an isopropyl group, the At–C bond is less polarised but also much weaker. In contrast, the bond remains strong whilst retaining a small At positive charge when At is bonded to an sp2carbon atom. Hence, these latter results rationalise why aromatic or aryl groups appear reasonably suited for a priori stable radiolabelling of biomolecules with211At in the context of alpha therapy. [ABSTRACT FROM PUBLISHER]