Experimental Detection of the Pentaazacyclopentadienide (Pentazolate) Anion, cyclo-N5â This work was funded predominantly by the Defense Advanced Research Projects Agency, with additional support from the Air Force Office of Scientific Research and the National Science Foundation. The mass spectrometer instrumentation at UCSB was supported under the Army Research Office Award no. DAAD19-00-1-0026. We thank Dr. Robert Corley, Dr. Arthur Morrish, Dr. Don Woodbury, Dr. Michael Berman, and Prof. W. Kaska for their support, and Dr. Michael Gerken, Dr. Thorsten Schroer, Dr. Stefan Schneider, Dr. Ralf Haiges, Dr. Ross Wagner, and Dr. Suresh Suri for their collaboration and stimulating discussions.

Abstract

The long-sought pentazolate anion, cyclo-N5−, the isoelectronic polynitrogen counterpart of the cyclopentadienide anion, has been experimentally detected for the first time. Using electrospray ionization mass spectrometry and carefully selected collision voltages, the aryl substituent in the para-pentazolylphenolate anion can be removed selectively without breaking the nitrogen–nitrogen bonds of the pentazolate anion (see scheme), thus delineating a synthetic method for the bulk synthesis of N5−.