iodine heptafluoride

Other names: iodine(VII) fluoride, heptafluoroiodine

IF₇

38/50 uncommon

Iodine heptafluoride is a remarkable hypervalent compound that pushes the boundaries of conventional bonding theory. First synthesized in 1954, this colorless crystalline solid features a central iodine atom surrounded by seven fluorine atoms in a pentagonal bipyramidal geometry. This unusual molecular arrangement consists of five fluorine atoms forming a pentagonal ring around the equator of the molecule, with the remaining two fluorine atoms positioned at the axial poles. The structure represents one of the few examples of the obscure D_5h pentagonal bipyramidal geometry in stable molecules, making it valuable for studying molecular orbital theory and demonstrating how iodine can expand its octet to accommodate seven bonds. IF₇ exhibits powerful oxidizing and fluorinating properties, reacting vigorously with organic materials and many metals. It decomposes rapidly in moisture, releasing corrosive hydrogen fluoride. Despite its high reactivity, it is relatively stable when properly stored, with a melting point of 4.5°C and a boiling point of 104.5°C. Iodine heptafluoride serves as an important reagent in specialized fluorination reactions and has been studied for potential applications in nuclear fuel processing.