Karl O. Christe

Karl Otto Christe (born July 24, 1936) is an inorganic chemist. He is known for developing safe methods of studying highly reactive and dangerous chemicals, while his extensive experience in fluorine chemistry has earned him the title of 'The Fluorine God'. His research covers fluorine chemistry of nitrogen and halogens and the synthesis of new energetic materials.

Karl Otto Christe
Born	Karl Otto Christe (1936-07-24) July 24, 1936 (age 89) Ulm, Germany
Alma mater	University of Stuttgart
Known for	Fluorine Chemistry and homoleptic nitrogen compounds
Awards	Tolman Award (2011)
Scientific career
Fields	Chemistry
Institutions	Loker Hydrocarbon Research Institute University of Southern California
Doctoral advisor	Josef Goubeau

Life

In 1957 Christe began his chemistry studies at the University of Stuttgart. He prepared both his diploma- (1960) and PhD theses (1961) under the supervision of Josef Goubeau. In 1962, Christe immigrated to the US and settled in California. He started working as a senior research chemist with Stauffer Chemical Co in Richmond/CA. In 1967 he joined Rocketdyne Division Rockwell International in Canoga Park where he became the manager of research in 1978. In 1994 he accepted split positions between the Air Force Research Laboratory at Edwards Air Force Base and the Loker Hydrocarbon Research Institute of USC. In 2005, he moved full-time to USC where he is working as a research professor.^[1][2][3]

Work

Since the 1960s, Christe has been investigating the synthesis of new fluorides of nitrogen, halogen, and the halogen oxides, as well as their ions. Notable examples are the syntheses of both NF₄⁺ and ClF₆⁺. On the occasion of the 100th anniversary of Henri Moissan's first production of fluorine, Christe in 1986 reported about the first truly chemical synthesis of fluorine. Another important field of his work covers the research on homoleptic nitrogen compounds for use in energetic materials. In this context, he synthesized the bent pentazenium cation, N₅⁺, and was the first to experimentally detect the cyclic pentazolate anion, N₅⁻ and to prepare stable high nitrogen pentazolates.^[4][5] Both compounds are considered important milestones on the way to even heavier polynitrogen compounds. In 1996, Christe was the first to propose the use of ionic liquids as energetic materials in propulsion systems. He is currently working on the development of oxidizers to replace the dangerous ammonium perchlorate. Christe has authored over 400 peer-review publications, and has more than 60 patents.

In 2025, remarking on the discovery of the hexanitrogen molecule, the most energetic molecule yet made, Christe wrote: "This work is spectacular and, in my opinion, is worthy of a Nobel prize." He continued: "Compared to carbon chemistry, where two Nobel prizes were awarded for the discovery of two new carbon allotropes (buckyballs and graphene), the experimental observation of a neutral molecular nitrogen allotrope is orders of magnitude more difficult." ^[6]

Awards

• 1969: Apollo Achievement Award, NASA
• 1986: ACS National Award in Fluorine Chemistry, American Chemical Society (ACS)
• 1999: Star Team Award, US Air Force
• 2000: Henri Moissan Award, Institution du Prix Moissan, Paris
• 2003: ACS National Award in Inorganic Chemistry Award, ACS
• 2006: Alfred Stock Memorial Prize, Gesellschaft Deutscher Chemiker
• 2010: European Academy of Sciences and Arts, Salzburg
• 2011: Richard C. Tolman Award, ACS
• 2015: ACS National Award for Creative Research and Applications of Iodine Chemistry
• 2017: Fellow of the American Association for the Advancement of Science
• 2021: ACS National Award M. Frederick Hawthorne Award in Main Group Inorganic Chemistry^[7]

Publications (selection)

• Guertin, Jacques P.; Christe, Karl O.; Pavlath, Attila E. (1966). "Complex Fluoro Cations. II. Tetrafluoronitrogen(V) Cation, NF₄⁺. Synthesis and Properties of NH₄⁺AsF₆⁻". Inorganic Chemistry. 5 (11): 1921–1924. doi:10.1021/ic50045a018.
• Christe, Karl O. (July 1, 1973). "Hexafluorochlorine(VII) cation, CIF6+. Synthesis and vibrational spectrum". Inorganic Chemistry. 12 (7). American Chemical Society (ACS): 1580–1587. doi:10.1021/ic50125a021. ISSN 0020-1669.
• Christe, Karl O. (1973). "Hexafluorochlorine(VII) cation, CIF₆⁺. Synthesis and vibrational spectrum". Inorganic Chemistry. 12 (7): 1580–1587. doi:10.1021/ic50125a021.
• Christe, Karl O. (1986). "Chemical synthesis of elemental fluorine". Inorganic Chemistry. 25 (21): 3721–3722. doi:10.1021/ic00241a001.
• Christe, Karl O.; Wilson, William W.; Sheehy, Jeffrey A.; Boatz, Jerry A. (1999). "N₅⁺: A Novel Homoleptic Polynitrogen Ion as a High Energy Density Material". Angewandte Chemie International Edition. 38 (13–14): 2004–2009. doi:10.1002/(SICI)1521-3773(19990712)38:13/14<2004::AID-ANIE2004>3.0.CO;2-7. PMID 34182671.
• Vij, Ashwani; Pavlovich, James G.; Wilson, William W.; Vij, Vandana; Christe, Karl O. (2002). "Experimental Detection of the Pentaazacyclopentadienide (Pentazolate) Anion, cyclo-N₅⁻". Angewandte Chemie. 114 (16): 3177. doi:10.1002/1521-3757(20020816)114:16<3177::AID-ANGE3177>3.0.CO;2-I.
• Jones, C. Bigler; Haiges, Ralf; Schroer, Thorsten; Christe, Karl O. (2006). "Oxygen-Balanced Energetic Ionic Liquid". Angewandte Chemie International Edition. 45 (30): 4981–4984. doi:10.1002/anie.200600735. PMID 16819744.
• Christe, Karl O. (2007). "Recent Advances in the Chemistry of N₅⁺, N₅⁻ and High-Oxygen Compounds". Propellants, Explosives, Pyrotechnics. 32 (3): 194–204. doi:10.1002/prep.200700020.