Tetranitratoborate

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Tetranitratoborate is an anion composed of boron with four nitrate groups. It can form salts with large cations such as tetramethyl ammonium nitratoborate,[1] or tetraethyl ammonium tetranitratoborate.[2]

The ion was first discovered by C. R. Guibert , M. D. Marshall in 1966 after failed attempts to make boron nitrate.[1]

The related molecule, boron nitrate B(NO3)3, has resisted attempts to make it, and if it exists it is unstable above -78°C.[2] Despite this non-existence it has a CAS number of 71816-39-2 and ChemSpider number of 25934735.

Other related ions are the slightly more stable tetraperchloratoborates, with perchlorate groups instead of nitrate, and tetranitratoaluminate[3] with the next atom down the periodic table, aluminium instead of boron ([Al(NO)4]-).

Formation[edit]

Tetramethyl ammonium chloride reacts with BCl3 to make (CH3)4NBCl4. Then the tetrachloroborate is reacted with N2O4 at around -20° to form tetramethyl ammonium nitratoborate, and other gases such as NO2Cl and Cl2.[2]

Another mechanism to make tetranitratoborate salts is to shake a metal nitrate with BCl3 in chloroform at 20°C for several days. Chloronitratoborate [Cl3BNO3]- is an unstable intermediate.

MNO3 + BCl3 M[Cl3BNO3]
4M[Cl3BNO3] 3M[BCl4] + MB(NO3)4][4]

Properties[edit]

The infrared spectrum of tetramethyl ammonium nitratoborate includes a prominent line at 1612 cm-1 with shoulders at 1582 and 1626 cm-1 attributed to v4. Also prominent is 1297 and 1311 cm-1 attributed to v1, with these vibrations due to the nitrate bonded via one oxygen.[1]

The density of tetramethyl ammonium nitratoborate is 1.555. It is colourless and crystalline. As tetramethyl ammonium nitratoborate is heated it has some sort of transition between 51°C and 62°. It decomposes above 75°C producing gas. Above 112° it is exothermic, and a solid is left if it is heated to 160°C.[2]

Tetramethyl ammonium nitratoborate is insoluble in cold water but slightly soluble in hot water. It does not react with water. I also disolves in liquid ammonia, acetonitrile, methanol, and dimethylformamide.[1] It reacts with liquid sulfur dioxide.[1][5]

At room temperature tetramethyl ammonium nitratoborate is stable for months. It does not explode with impact.[1]

Alkali metal tetranitratoborates are unstable at room temperature and decompose.[4]

1-Ethyl-3-methyl-imidazolimium tetranitratoborate was discovered in 2002. It is an ionic liquid that turns solid at -25°C.[6]

References[edit]

  1. ^ a b c d e f Guibert, C. R.; M. D. Marshall (1966). "Synthesis of the Tetranitratoborate Anion". Journal of the American Chemical Society 88 (1): 189–190. doi:10.1021/ja00953a051. ISSN 0002-7863. 
  2. ^ a b c d Titova, K. V.; V. Ya. Rosolovskii (1970). "Tetraalkylammonium nitratoborates". Bulletin of the Academy of Sciences of the USSR Division of Chemical Science 19 (12): 2515–2519. doi:10.1007/BF00854900. ISSN 0568-5230. 
  3. ^ Jones, CJ Bigler (2007). Transition and Main Group Metals Applied to Oxidative Functionalization of Methane and Use as High Oxygen Carriers for Rocket Propellants. ProQuest. p. 139. ISBN 9780549231066. Retrieved 3 February 2014. 
  4. ^ a b Titova, K. V.; V. Ya. Rosolovskii (1975). "Reaction of nitrates of monovalent cations with BCl3". Bulletin of the Academy of Sciences of the USSR Division of Chemical Science 24 (10): 2246–2248. doi:10.1007/BF00929774. ISSN 0568-5230. 
  5. ^ C.C. Addison and D. Sutton. Progress in Inorganic Chemistry 8. p. 216. 
  6. ^ Jones, C. Bigler; Ralf Haiges, Thorsten Schroer, Karl O. Christe (2006). "Oxygen-Balanced Energetic Ionic Liquid". Angewandte Chemie International Edition 45 (30): 4981–4984. doi:10.1002/anie.200600735. ISSN 1433-7851.