Hypervalent Bonding in the OF(a⁴Σ^-), SF(a⁴Σ^-), SF₅/SF₆, and OSF₄ Species

Hypervalency has struggled the conventional wisdom of too many chemists for so many years. Numerous theories and bonding models have been introduced but the so-called "hypervalency" mystery remains. We offer a simple and appealing explanation for the bonding mechanism of OF(a⁴Σ^-), SF(a⁴Σ^-), SF₅/SF₆, and OSF₄ based solely on the fact that excited and/or ionic states of the constituent fragments may and actually do occur in the ground states of so many "every day" molecules. In particular, and through multireference methods, we have found that the bonding in all the studied species is ionic in nature, perhaps contrary to the present status of our chemical beliefs. Although the "atoms in molecules" hypothesis is certainly not the only way to explain the formation of the chemical bond, we strongly believe that it is the simplest and most economical conceptual principle that should guide our chemical thinking.