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Bonding or Nonbonding? Description or Explanation? “Confinement Bonding” of He@adamantane
Author(s) -
Wang ShuGuang,
Qiu YiXiang,
Schwarz W. H. Eugen
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200802596
Subject(s) - adamantane , antibonding molecular orbital , pauli exclusion principle , chemical physics , chemistry , theoretical physics , chemical bond , product (mathematics) , computational chemistry , crystallography , physics , quantum mechanics , mathematics , electron , geometry , organic chemistry , atomic orbital
Abstract Insight into bonding phenomena depends on whether one analyzes the whole bond‐formation process or just the final product. Examination of the formation of the inclusion complex He@adamantane by energy partitioning reveals that the high energy cost of “He bonding” originates in strong HeC Pauli repulsions. The postulate of attractive HeC bonds requires a very specific view.Different insights into chemical phenomena are obtained by analyzing the whole process (comparing three or more points, thereby explaining the atomistic mechanism) or only the final product (yielding an interesting fingerprint of the result). The viewpoint depends also on whether one analyzes the wavefunctions according to notions grounded in chemical experience or along physically well‐defined formal concepts. Bond energies can only be understood upon comparing both ends of the formation process from fragments to molecule. We examine the formation of the inclusion complex He@adamantane. The large antibonding energy expense is partitioned into four physical contributions according to chemical concepts. Introduction of the He atom into an undeformed adamantane cage leads to a large increase of Pauli repulsion; this is partly moderated by electrostatic overlap attraction and by electronic and nuclear relaxations. The IUPAC definition of bonding comprises this antibonding interaction, since a (meta)stable complex is formed. We call it “confinement bonding”. Single‐point analyses of the bond‐formation product can only yield one‐sided characterizations. Any analysis depends on its prescription, which should always be specified in order to avoid controversies based on a mix up of unlike concepts.