NEWS OF THE WEEK
NEW N2 RADICAL ISOLATED NITROGEN CHEMISTRY: New complexes protect normally highly unstable anion
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ITHIN THE PROTECTIVE framework of exot-
ic metal complexes, scientists have now isolated the reactive, triply reduced N23– radical. In addition to broadening the field of dinitrogen chemistry, the work adds to efforts to develop reactions that could be used in fertilizer-making processes—methods that are milder than the ubiquitous Haber-Bosch method, which reduces N2 under high temperatures and pressures to form ammonia. The work culminates years of effort from the lab of William J. Evans, chemistry professor at the University of California, Irvine, and colleagues there and at UCLA. In their complexes, the N23– anion is bonded to a complex containing potassium as well as a pair of complexes containing either dyspropsium or yttrium (J. Am. Chem. Soc., DOI: 10.1021/ja9036753). “It is always exciting when new types of N2 compounds are discovered, and the identification of compounds with N23– radicals may open unique pathways for dinitrogen functionalization,” notes Paul J. Chirik, a chemistry professor at Cornell University. The yttrium compounds are “particularly striking additions to the library of known N2 compounds,” he adds. Michael D. Fryzuk, a chemistry professor at the University of British Columbia, Vancouver, calls the work “remarkable chemistry. It is rare that such a completely new form of a small molecule, N23–, is uncovered and completely characterized.” Although dinitrogen complexes obtained by 1-, 2-, and 4-electron reductions have been studied, the N23–
anion’s radical nature has made TRAPPED RADICAL A complex it a slippery target. Evans tells containing yttrium (pink)-based C&EN that the unusual metals in ligands allows the normally unstable the complexes—dysprosium and N23– ion to exist. (Blue = nitrogen, yttrium, which tend to form ionic green = silicon, red = oxygen, bonds, which don’t share their yellow = potassium, gray = carbon.) electrons and thus don’t interact very much—made it possible to isolate the ion. In metals that tend to form covalent bonds, the charge density is smeared between two bound atoms, and “the unpaired electron on this ion might communicate better with the surroundings and find another electron with which to pair,” he explains. Through an exhaustive analysis that included electron spin resonance spectroscopy and Raman spectroscopy, as well as computational validation with density functional theory, Evans says they’ve discovered that the anion’s unpaired electron appears to be in an orbital that is isolated from and protected by the metal-ligand framework. “This may mimic how nature protects very reactive intermediates,” he says. N23– is electronically analogous to the radical superoxide, O2–, an ion that plays important roles in immune system biochemistry, as well as acting as a source of oxygen on spacecraft and submarines. The electronic resemblance raises a quandary in naming the new ion. The N23– anion isn’t listed in the 2005 IUPAC Nomenclature of Inorganic Chemistry, “presumably because no one thought this species could exist,” Evans says. The group is anticipating how IUPAC will weigh in: Calling it a dinitride? Or, in keeping with the superoxide analogy, perhaps supernitride?—ELIZABETH WILSON WITH REPORTING BY JYLLIAN KEMSLEY
EUROPE European Commission suspends chemical trade association from lobbying register The European Commission has suspended the European Chemical Industry Council (CEFIC) from a voluntary lobbying register for eight weeks. The suspension follows a complaint by the environmental group Friends of the Earth Europe (FOEE) claiming that lobbying cost figures submitted by the trade association for 2007 are unrealistically low. In its complaint, FOEE noted that CEFIC, with a staff of 170 and an annual budget of $54 million, reported that its costs directly related to representing interests to European Union institutions amounted to $71,000. FOEE alleges that
a budget figure taking into account staff, publications, and events would be considerably higher. The commission concurred. “The Secretariat General has received some information from CEFIC that led it to consider that the declaration of CEFIC may indeed raise problems as regards its estimate of expenditures,” it says in a statement. CEFIC has been given a chance to restate its lobbying budget. “CEFIC is not at all transparent about its lobbying work,” says Paul de Clerck, corporates campaigner at FOEE. “They make a joke of the commission’s lobby
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register by reporting a completely false lobby budget.” CEFIC has issued a response expressing support for the European Transparency Initiative, a voluntary program under which the EC registers lobbying groups. The trade association claims, however, that arriving at a specific figure for lobbying of EU institutions is difficult given its scope and its interactions with members and other associations. “CEFIC will reconsider its current position once the official statement of the commission and clearer guidance will have been received,” it says.—RICK MULLIN
