title: Detection of Cyclo-N5-in THF Solution.
abstract: Compelling evidence has been found for the formation and direct detection of the cyclopentazole anion (cyclo-N5-) in solution. The anion was prepared from phenylpentazole in two steps: reduction by an alkali metal to form the phenylpentazole radical anion, followed by thermal dissociation to yield cyclo-N5-. The reaction solution was analyzed by HPLC coupled with negative mode mass spectrometry. A signal with m/z 70 was eluted about 2.1 min after injection of the sample. Its identification as N5was supported by single and double labeling with15N, which yielded signals at m/z=71 and 72, respectively, with identical retention times in the HPLC column. MS/MS analysis of the m/z=70 signal revealed a dissociation product with m/z=42, which can be assigned to N3-. To our knowledge this is the first preparation of cyclo-N5-in the bulk. The compound is indefinitely stable at temperatures below -40 °C, and has a half-life of a few minutes at room temperature.
authors.affiliation: Institute of Chemistry, Safra Campus, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel.
authors.forename: Boris
authors.initials: B
authors.lastname: Bazanov
authors.affiliation: Institute of Chemistry, Safra Campus, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel.
authors.forename: Uzi
authors.initials: U
authors.lastname: Geiger
authors.affiliation: Head of the EPR lab, Department of Chemical Research Support, Weizmann Institute of Science, 76100, Rehovot, Israel.
authors.forename: Raanan
authors.initials: R
authors.lastname: Carmieli
authors.affiliation: Institute of Chemistry, Safra Campus, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel.
authors.forename: Dan
authors.initials: D
authors.lastname: Grinstein
authors.affiliation: Institute of Chemistry, Safra Campus, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel.
authors.forename: Shmuel
authors.initials: S
authors.lastname: Welner
authors.affiliation: Institute of Chemistry, Safra Campus, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel. yehuda.haas@mail.huji.ac.il.
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Haas
keywords: cyclopentazolate anion; high energy density materials; nitrogen heterocycles; phenylpentazole; radical anions