NEWS OF THE WEEK EDUCATION
STATE DEPARTMENT EXTENDS MANTIS New clearance period announced for foreign students and researchers
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Boehlert
NTERNATIONAL STUDENTS WHO
pass therigoroussecurity check known as Visas Mantis will now be cleared for the length of their academic program for a maximum of four years, following changes to the program announced by the State Department on Feb. 11. Similarly, temporary workers, exchange visitors, and intracompany transfers can be cleared for the duration of their programs for up to two years. Previously the clearance lasted for only one year. The Mantis process was repeated each time
INORGANIC
an individual had to renew his or her visa. Under the new system, students and scientists returning to the same program within the set time frame can renew their visas without another Mantis check. "The extension of the validity of Mantis is a commonsense reform that reextends the hand of welcome to the world's best and brightest and refocuses the attention of visa officials on applicants who are far more likely to present a threat to U.S. security," says Rep. Sherwood L. Boehlert (R-N. Y), chairman of
CHEMISTRY
AMMONIA IS READY FOR A TRANSFER Iridium insertion into N - H bond opens door to catalytic amination reactions
N-H ACTIVATE Iridium complex quickly inserts into NH3at room temperature.
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Hartwig 12
C&EN
/ FEBRUARY
HE DESIGN AND SYNTHESIS
of an iridium complex that undergoes oxidative addition of ammonia to form an amido hydride derivative appears to have solved one of chemistry's long-standing research challenges: how to activate N - H bonds under mild conditions. This fundamental breakthrough could lead to industrially important catalytic ammonia-transfer processes. Chemists have known for a century that ammonia forms simple M - N H 3 coordination complexes with most transition metals. Transition-metal complexes also are known to insert into gen-
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2005
erally unreactive X-H bonds ofhydrogen, silanes, boranes, and alkanes (where X = H, Si, B, or C). But no one, until now, had designed a metal-ligand system that is thermodynamically favored to insert into an N - H bond of ammonia. Graduate student Jing Zhao and chemistry professor John F. Hartwig at Yde University along with chemistry professor Alan S. Goldman at Rutgers University, Piscataway N.J., have accomplished the feat with an iridium complex that contains a tridentate pincer-type ligand [Science, 307, 1080 (2005)1. The key to their success was increasing the
the House Committee on Science. The State Department implemented the Visas Mantis program in 1998 to control illegal technology transfer in sensitive scientific areas. The number of applications sent for screening dramatically increased after the Sept. 11, 2001, terrorist attacks, creating a backlog of pending visas. Representatives from higher education and research communities challenged the system, blaming long visa delays for discouraging foreign scientists from studying and working in the U.S. Last February, the Government Accountability Office released a study showing that applicants identified as needing a Visas Mantis clearance were waiting an average of 67 days to be notified of their status. The State Department is claiming that improvements to the process since then have decreased the wait to an average of 14 days.-VICTORIA GILMAN
electron density on the already electron-rich iridium atom. Their starting point was a known complex having an aromatic tridentate ligand that can insert into C-H bonds and aniline N - H bonds but reacts with ammonia to give the classical coordination complex By replacing the aromatic tridentate ligand with an aliphatic version, they boosted electron density on the metal enough to enable it to insert into an N - H bond of ammonia. The researchers treated the new complex with olefins to form intermediates that dissociate when ammonia is added at room temperature, quickly forming the amido hydride complex The next step will be to develop procedures to transfer the amido group to substrates. Possibilities include coupling the complex with alkyl or aryl groups to incorporate nitrogen into pharmaceuticals and olefin amination to make nitrogen-containing monomers, the researchers note.-STEVE RITTER HTTP://WWW.CEN-ONLINE.ORG
