Selective Emergence of Halogen Bond in Ground and Excited States of Noble‐Gas—Chlorine Systems

Molecular‐beam scattering experiments and theoretical calculations prove the nature, strength and selectivity of halogen‐bond (XB) in the interaction of halogen molecules with the series of noble‐gas (Ng) atoms. The XB, accompanied by charge transfer from the Ng to the halogen, is shown to take place in, and measurably stabilize, the collinear conformation of the adducts, which thus becomes – in contrast to what happens for other Ng‐molecule systems – approximately as bound as the T‐shaped one. Remarkably, we also show how and why XB is inhibited when the halogen molecule is in the 3Πu excited state. A general potential formulation fitting the experimental observables, based on few physically essential parameters, is proposed to describe the interaction accurately and is validated by ab‐initio computations.

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