This book reviews research on the thermodynamic, magnetic susceptibility, solid-state 19F NMR and structural data for molecular hexafluorides and hexafluoro complexes related to interpretation of intermolecular interactions and structural properties. Along with conceptual problems associated with the application of methods theoretical and quantum chemistry, this work addresses the relationships between some fundamental properties of co-ordinate bonding and correlation effects, the electron-density transfer, and corrections for relativistic s-orbital contraction, d- and f-orbital expansion and destabilisation and spin-orbit coupling.