Abstract:
N 2  F 3  SnF 5  is formed by reacting N 2  F 3  SbF 6  and Cs 2  SnF 6  in the presence of HF. N 2  F 3  SnF 5  is useful as a component of NF 3  -F 2  gas generating compositions.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a composition of matter which is useful in NF 3  -F 2  gas generator formulations. 
     2. Description of the Prior Art 
     In the recent past, certain new self-clinkering NF 4   +  salts have been synthesized. Among these are (NF 4 ) 2  SnF 6 , NF 4  SnF 5 , (NF 4 ) 2  TiF 6 , NF 4  TiF 9 , NF 4  Ti 3  F 13 , NF 4  Ti 6  F 25  and (NF 4 ) 2  NiF 6 . When such self-clinkering salts are utilized as oxidizers and combined with a fuel such as aluminum, NF 3  gas, F 2  gas and solids are produced when the combination is burned. The gases are useful as lasing materials. The fact that solids or &#34;clinkers&#34; are produced is important in that it overcomes a disadvantage present when, for example NF 4  BF 4  is used as the oxidizer. When NF 4  BF 4  is used, NF 3 , F 2  and another gas, BF 3 , are produced. The gaseous BF 3  is not useful as a laser material and acts to deactivate the laser. By producing a solid or &#34;clinker&#34; instead of gases other than NF 3  and F 2 , the self-clinkering salts overcome this problem. 
     Frequently, formulations containing NF 4   +  salts require burning rate modifiers. Typically, N 2  F 3   +  salts which are more reactive than NF 4   +  salts can be used. However, insofar as is known from the prior art, no self-clinkering N 2  F 3   +  salts are available. 
     SUMMARY OF THE INVENTION 
     According to this invention, a self-clinkering N 2  F 3   +  salt which is useful as a burning rate modifier has been prepared. The salt has the formula N 2  F 3  SnF 5 . Synthesis is accomplished by means of a reaction between N 2  F 3  SbF 6  and Cs 2  SnF 6  in HF. Insofar as is known by the inventors, the salt of this invention is the first self-clinkering N 2  F 3   +  salt ever produced. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The salt, N 2  F 3  SbF 6 , may be prepared according to the procedure set forth in the following example 
     EXAMPLE I 
     Synthesis of N 2  F 3  SbF 6 . A Teflon amplule, containing a Teflon coated magnetic stirring bar and equipped with a stainless steel valve, was loaded with 14.4 mmol of SbF 5  in a glovebox. The ampule was then attached to a vacuum line and 2 ml of anhydrous HF was condensed into the ampule at -78° C. while stirring and warming to ambient temperature. The system was then pressurized with N 2  F 4  (1 atm). A gradual decrease in the pressure was noted due to uptake of N 2  F 4 . Periodic cycling to below 0° C. seemed to increase the rate of N 2  F 4  uptake. After several hours the unreacted N 2  F 4  and HF solvent were pumped off at 40° C. until constant weight was achieved. The observed weight gain corresponded to the reaction of 12.1 mmol of N 2  F 4 . When the reaction was repeated on a larger scale with 8 ml HF for 3 days, it was found that 74.0 mmol of SbF 5  reacted with 73.5 mmol of N 2  F 4  to give 23.66 g of N 2  F 3  SbF 6  (weight calcd for 74.0 mmol of N 2  F 3  SbF 6  23.74 g), which was characterized by  19  F NMR and vibrational spectroscopy. 
     To produce the salt of this invention, N 2  F 3  SnF 5 , one utilizes N 2  F 3  SbF 6  obtained from Example 1 and Cs 2  SnF 6  and carries out the procedure set forth in the following example. 
     EXAMPLE II 
     Solid N 2  F 3  SbF 6  (6.43 mmol) and Cs 2  SnF 6  (3.24 mmol) were placed in a well passivated (with CIF 3 ) Monel vacuum line equipped with Teflon-FEP U traps and diaphragm values. Approximately 2 ml of anhyrous HF was added. After stirring and shaking vigorously for 30 minutes at room temperature, some of the HF was removed under vacuum and the mixture was cooled to -78° C. The solid and liquid phases were separated by pressure filtration and the volatile products were removed by pumping at 25° C. for 15 hours. The volatile material was separated by fractional consideration and consisted of the HF solvent and N 2  F 4  (3.2 mmol). The filtrate residue (0.3 g) was analyzed by means of vibrational and NMR spectroscopy and shown to be N 2  F 3  SnF 5 . 
     When N 2  F 3  SnF 5  is combined with a fuel such as aluminum and burned NF 3  gas, F 2  gas, N 2  gas and a solid are obtained. (Since N 2  is normally used as an inert diluent its formation does not degrade the performance of a laser.) Thus N 2  F 3  SnF 5  is self-clinkering. That is, a non-gaseous product (the solid or &#34;clinker&#34;) rather than a gaseous product (such as the BF 3  produced when NF 4  BF 4  is burned) results upon burning of N 2  F 3  SnF 5 . In addition, the useful gases NF 3  and F 2  (and N 2 ) are produced. Insofar as is known by the inventors, N 2  F 3  SnF 5  is the only self-clinkering N 2  F 3   +  salt that has ever been produced to date.