Nitrogen Pentafluoride and Related Compounds
Between nitrogen pentafluoride and related species, and the helium compounds of Chapter 5, there is is a curious link, beyond the fact that both species are experimentally unknown: the two classes appear to violate a cherished valence rule. The octet rule, which supposedly summarizes the appetite for electrons of atoms of the first full row of the periodic table (“first-row atoms” to computational chemists), decrees that the elements from lithium to neon cannot have more than eight electrons in their valence shells. Hydrogen and helium might be said to be subject to an analogous, duplet, rule, stating that their valence shells are limited to two electrons. Yet plausible computations indicate that compounds can exist which appear to defy these rules. In this chapter we examine molecules in which nitrogen and some nearby elements formally violate the octet rule, and consider whether this transgression is real.
Molecules that seem to violate the octet (or duplet) rule are hypercoordinate...
KeywordsAtomic Orbital Imaginary Frequency Valence Shell Axial Bond Octet Rule
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