Nitrogen: breaking up is hard to do.

Though humans live in a sea of nitrogen, which makes up 78 percent of Earth's atmosphere, chemists have had a hard time harnessing the inert gas for practical purposes.

Nature takes exquisite advantage of gaseous N2, "fixing" nitrogen by means of biological processes that split the tightly bound molecules before weaving individual nitrogen atoms into compounds. Yet the seemingly simple task of nitrogen fixation continues to stymie chemists seeking easier ways to use the gas in industrial processes.

In the May 12 Science, chemists Catalina E. Laplaza and Christopher C. Cummins of the Massachusetts Institute of Technology report a novel process for splitting up N2. They use an intermediate molybdenum-containing molecule to cleave the two nitrogen atoms.

Since nitrogen plays such a strong role in organic chemistry, a technique that makes the element more available for chemical synthesis offers great practical opportunities, the chemists observe. Such a method "is clearly desirable if this immense natural resource is to be utilized optimally," they say.

Not surprisingly, the feature that makes nitrogen so stable and inert -- a triple bond holding the N2 together --throws up the greatest obstacle to freeing the two atoms to react with other elements. In the new method, the molybdenum-bearing molecule cuts the triple bond and picks up both nitrogen atoms, attaching each to an intermediary chemical complex in readiness for further reactions.

The researchers designed the nitrogen-cleaving molecule with a novel structure that they thought "would display unusual reactivity, and in fact it does."

Conveniently, the reaction takes place in a cool solution of hydrocarbons at ordinary air pressure. "There are no other well- documented reactions that occur the same way, making this manner of N2 cleavage quite interesting," Cummins says.

He believes that the new method's primary contribution may be simply to spark inquiry into other, related methods of cleaving nitrogen molecules. "The work of Laplaza and Cummins has revealed many interesting prospects, most of which have been only aspirations, or paper chemistry, until present," says G.J. Leigh, a chemist at England's University of Sussex. Having long tried to mimic nature's methods of nitrogen fixation, Leigh adds, chemists may now see in the work of Laplaza and Cummins a chemical reaction "that is radically different."