Chemical Structures from the Analysis of Domain-Averaged Fermi Holes. Hypervalence and the Nature of Bonding in Isocoordinated Molecules SF6 and CLi6

The nature of bonding in isocoordinated molecules of SF 6 and CLi 6 was analyzed using the recently proposed approach based on the scrutiny of the so-called domain-averaged Fermi holes. It has been shown that although the molecule of SF 6 does not satisfy the charge criterion of hypervalence, the actual picture of bonding is consistent with the traditional hypervalent model assuming the existence of six localized albeit very polar SF bonds around the central atom. On the other hand, while the molecule of CLi 6 represents the ideal candidate for hypervalence according to charge criterion, the picture of bonding is, in this case, considerably different from what the concept of hypervalence is traditionally associated with and can be better characterized by the term hypercoordination.