Nitrogen is a common element that comprises seventy-five percent of the air that surrounds us. It is well documented and generally accepted that nitrogen makes maximum of 4 bonds. Recently, however, researchers at the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw used computer simulation to predict nitrogen bond with six fluorine atoms, contrary to century old convention.
Dr. Patryk Zaleski-Ejgierd (IPC PAS), principal investigator behind the simulation states, “We analyzed thousands of crystal structures of nitrogen compounds with fluorine arising at high pressures. We were hoping to see some structures containing nitrogen pentafluoride NF5 particles. We were completely unprepared for the fact that in one of the crystals we ran into ions with the formula NF6- in which the nitrogen atom bonds with as many as six fluorine atoms.” Despite his anticipation to see structures of nitrogen with five bonds, Ejgierd discovered a novel method to predict the formation of NF6.
The simulation indicates that the crystals will only occur at incredibly high temperatures–400 to 500 thousand atmospheres.
Although only a simulation, the results are encouraging and exciting because the conditions set forth are attainable with current technology. According to Ejgierd, “A reorganization takes place during which the molecular crystal, originally formed of a mixture of gases NF3 and F2, transforms into a complex ionic crystal constructed of NF4-, NF2+ and NF6- ions.”
Ejgierd is the first chemist to discover a stable crystal in which nitrogen breaks the octet rule-the requirement to possess eight valence electrons-and forms bonds involving a total twelve electrons. Compounds in which an element breaks the octet rule octet are called hypervalent. Many elements are known to form hypervalent compounds such as sulphur and phosphorous. This phenomenon is valued by chemists because it may allow for the formation of many novel compounds. For example, the hypervalent nature of sulfur forms sulphuric acid and, similarly, the hypervalency of phosphorus allows it to be one of the building blocks of DNA. In relation to the importance of the hypervalency of sulfur and phosphorous, the hypervalency of nitrogen indicates a wide range of new and exciting compounds.
Mr. Lin, a chemistry teacher at Brooklyn Technical High School, notes, “The idea behind nitrogen being able to form six chemical bonds is very interesting.” He suggests that with today’s technology, man-made experiments are able to alter the properties of elements and hopes to see the future of what this abundant, yet complex element can offer.