The present volume, "Fluorine" Suppt. Vol. 4, covers the oxygen compounds of fluorine and the binary fluorine-nitrogen compounds. In the first part "Fluorine and Oxygen", oxygen fluorides OnF m are described in the order of decreasing F: 0 ratio. It finishes with a description of hyperfluorous acid HOF. The second part "Fluorine and Nitrogen" deals with the binary fluorine-nitrogen com pounds. They are subdivided on the basis of the number of nitrogen atoms per molecule. Thus, species such as NFt, NF , NF , and NF are considered first followed by the dinitrogen and 3 2 trinitrogen fluorides NF, NF, and NF and related ions. 2 4 2 2 3 The other compounds under the heading "Fluorine and Nitrogen", the fluorine-nitrogen hydrogen and the fluorine-nitrogen-oxygen(-hydrogen) compounds, will be covered in "Fluorine" Suppt. Vol. 5. Intense development in the field of inorganic fluorine-oxygen and fluorine"nitrogen chem istry began in the middle of the 1950s when in less than a decade numerous previously unknown compounds and a great deal of new information were produced. Research in this field was strongly stimulated by interest in these compounds as potential high-energy oxi dizers for rocket fuels. That is also the reason why much of the pertinent chemical information is found in patent Iiterature and U.S. Government contractor reports.

"Nitrogen" Suppt. Vol. B 1 describes the compounds of nitrogen with noble gases and, in the major part, binary compounds composed of one nitrogen atom and hydrogen. Nitrogen hydrogen compounds with two and more nitrogen atoms are covered in "Nitrogen" Suppt. Vol. 82. There is some information on various nitrogen-noble gas species, to a large extent because of the interest in their bonding behavior. Experimental data have been obtained chiefly for some singly charged cations, particularly those formed by argon Like ArN + and ArNi. The existence of others has only been established by mass spectrometry. The binary compounds of nitrogen and hydrogen comprise NH, NH , NH , NH , the corre 2 4 5 sponding ions, and some adducts. NH and NH1 are not treated. The predominant part 3 of the volume covers the description of the molecules NH and NH . 8oth species are present 2 in photolytic processes in the atmosphere. They play an essential role in combustion systems regardless of whether the nitrogen stems from the nitrogen-containing fuel or from the air. Thus, much work has been devoted to the understanding of the nitrogen chemistry in combustion and in the atmosphere. The production and detection methods as weiL as the reactions have been comprehensively described. ln addition detailed information is given on the spectral behavior, the knowledge of which is important for detecting the mole cules and for studying their kinetics.

"Nitrogen" SuppL. Vol. 82 continues the description of binary compounds composed of nitrogen and hydrogen (nitrogen hydrides). While" Nitrogen" SuppL. Vol. 81 covers mono- nitrogen compounds, the present volume comprises compounds having two, three, four, or more nitrogen atoms. Hydrazine, N H , and its ions N2Ht and N2H~+ were not included. 2 4 (Reference is made to a voluminous monograph: E.W. Schmidt, Hydrazine and its Deriva- tives: Preparation, Properties, Applications, Chichester 1984, 1088 pages.) Among the dinitrogen compounds, the diazenyl cation, N H+, has been extensively inves- 2 tigated, especially in regards to spectroscopic and kinetic properties, because of its occur- rence in interstellar space. Chemically well-characterized are diazene, N H , the simplest 2 2 unsaturated nitrogen hydride which is used as a hydrogenation reagent, and the hydrazyl radical, N H , which is frequently present as an intermediate during the formation and 2 3 decay of nitrogen-hydrogen compounds. The major portion of this volume is taken up by hydrogen azide or hydrazoic acid, HN , the first member in the series of trinitrogen compounds. Known to be highly explosive 3 in pure form, it can be safely handled when diluted. Thus, a great deal of information is available mainly on its properties as a chemical reagent and its decomposition processes.