K. O. Christe

Thermochemistry of NF4+ salts

Abstract The decomposition, solid phase change, and the formation enthalpies were determined for NF 4 BF 4 , NF 4 PF 6 , NF 4 AsF 6 , NF 4 SbF 6 , NF 4 GeF 5 and (NF 4 ) 2 GeF 6 by differential scanning calorimetry. It is shown that (NF 4 ) 2 GeF 6 is an intermediate in the decomposition of NF 4 GeF 5 . The enthalpies of reaction in water of NF 4 BF 4 , NF 4 PF 6 , NF 4 AsF 6 and NF 4 SbF 6 were measured and used to obtain an alternate set of formation enthalpies for these compounds. Recommended values for H f ∘(NF 4 XF) (s) are: NF 4 BF 4 = −1410±5, NF 4 SbF 6 = −1669±12, NF 4 AsF 6 = −1538±11, NF 4 PF 6 = −1841±7, NF 4 GeF 5 = −1473±1, and (NF 4 ) 2 GeF 6 = −1606±5 kJ mol −1 . The formation enthalpies of the NF 4 + salts were used to estimate the F + ion affinity of NF 3 and the enthalpy of formation of gaseous NF 4 + . The reaction enthalpy of the process NF 3 (g) + F 2(g) → NF 4 + F − (s) was estimated.

Syntheses and vibrational spectra of chlorofluoramines

Abstract The chlorofluoramines NFCl 2 and NF 2 Cl were prepared by fluorination of an NH 4 Cl-NaCl mixture and characterized by vibrational spectroscopy. For NF 2 Cl, two fundamental vibrations were reassigned.

Thermochemistry of NF4+ salts. On the enthalpy of formation of NF4XeF7 and the NF4SbF6-BrF3 system

Abstract The thermal decomposition of NF 4 XeF 7 was studied by differential scanning calorimetry. From the observed enthalpy of decomposition, a value of −491 kJ mol −1 was calculated for ΔH f o (NF 4 XeF 7(s) ). The reaction of NF 4 + salts with BrF 3 , previously suggested [1] for the determination of more precise thermochemical values for NF 4 + salts by solution calorimetry, was shown to be infeasible.

New synthesis of IF5O

Abstract Phosphorus trifluoride oxide readily replaces two fluorine ligands in IF 7 for a doubly bonded oxygen atom, thereby providing a new and convenient synthesis for IF 5 O. Attempts to extend this method to the syntheses of either IF 3 O 2 or IFO 3 were unsuccessful due to competing deoxygenation reactions of the iodine oxyfluoride precursors. Furthermore, PF 3 O does not undergo fluorine-oxygen exchange with the NF 4 + cation.

On the synthesis of the N2F+5 cation. A critical comment on the paper by Toy and Stringham.

Abstract Toy and Stringham recently reported [1] the synthesis of N 2 F + 5 (CF 3 ) 3 CO - , a salt containing the novel pentafluorohydrazinium cation. This cation would be of significant academic and practical interest [2] since it would constitute the first known example of a substituted NF + 4 cation, i.e. an NF + 4 cation in which a fluorine ligand is replaced by an NF 2 group. According to the authors of [1], N 2 F + 5 (CF 3 ) 3 CO - was formed in a very unusual reaction involving the transfer of a fluorine cation from (CF 3 ) 3 COF to N 2 F 4 according to: