Antibond Breaking-The Formation and Decomposition of He@Adamantane: Descriptions, Explanations, and Meaning of Concepts

The reaction path from the inclusion complex He@adamantane to its two separated fragments over the transition barrier is investigated by using quantum chemistry. The changes of structure and wavefunction are intuitively anticipated, accurately computed, and qualitatively rationalized. With the help of the traditional concepts of chemical bonding and nonbonding interactions, and with numerical results from a chemically oriented energy-partitioning approach, we can rationalize the details of the chemical process, and qualitatively predict and interpret the two chosen alternative descriptions: the energy-partitioning approach and the topological electron-density analysis. The meaning of bonding within these two approaches, and unsolved aspects of the latter tool are clarified.