Encapsulation of Astatide by a water cage

A 5(12) cage of (H2O)(20) consisting of 30 hydrogen bonds encapsulates Astatide with little geometrical distortion. The cage is marginally destabilized but the non-covalent interactions are actually strengthened. Host center dot center dot center dot cage interactions in the [At@(H2O)(20)](-) cluster are anti-electrostatic, placing both negatively charged atoms in direct contact as in At delta-center dot center dot center dot O delta--H delta+. An orbital interaction analysis reveals that explicit host center dot center dot center dot cage contacts are inverted hydrogen bonds. That is, the same n(Lambda t) -> sigma(O-H) * type of donor -> acceptor charge transfer as in hydrogen bonding, with no proton bridging the two negative charges.

Automated summary

This passage describes a cage-like structure (H2O)(20) consisting of 30 hydrogen bonds, which successfully encapsulates Astatide with minimal geometrical distortion. While the stability of the cage is slightly destabilized, the non-covalent interactions are actually strengthened. In the [At@(H2O)(20)](-) cluster, the host center dot center dot center dot cage interactions are anti-electrostatic, bringing both negatively charged atoms in direct contact as in At delta-center dot center dot center dot O delta--H delta+. An analysis of orbital interactions reveals that the explicit host center dot center dot center dot cage contacts are inverted hydrogen bonds, involving the same type of donor -> acceptor charge transfer as in hydrogen bonding, without a proton bridging the two negative charges.