Charles B. Colburn

Analysis of the NMR and Double‐Resonance Spectra of the Isomers of N2F2

The assignment of F19 NMR spectra of the two isomers of N2F2 is consistent with the assumption of trans and cis 1,2‐difluorodiazine structures for these molecules. The qualitative features of the F19—{N14} double‐resonance spectra, and a comparison of the F19 NMR spectra at 56.4 and 40.0 Mc/sec strongly favor a cis structure over a 1,1‐difluorodiazine structure for the more reactive isomer. A comparison of the indirect N–F coupling constants for the two isomers indicates that the FNN angles are probably quite different for cis and trans N2F2.

An EPR Study of the Tetrafluorohydrazine‐Difluoramino Equilibrium

The EPR spectrum of the difluoramino radical (NF2) was observed to be a single broad line at a pressure of 20–40 mm of N2F4 and a temperature of 340–435°K. The peak‐to‐peak linewidth was observed to be 104 gauss with a g value of 2.010. From the temperature dependence of the line amplitude, the ΔH of dissociation of N2F4 was calculated to be 19.3±1.0.

Strength of the N–F Bonds in NF3 and of N–F and N–N Bonds in N2F4

The heat of formation of the difluoroamino free radical is found to be 8.9±2.5 kcal/mole. The NF2–F bond in NF3 is the weakest bond in NF3 in contrast to ammonia where the NH2–H bond is the strongest bond. The strength of the NF2–F bond is 57.1±2.5 kcal/mole while the average NF bond strength in NF2 and N2F4 is 71 kcal/mole. The strength of the N–N bond in tetrafluorohydrazine, as determined from appearance potential data, is 20.7 kcal in excellent agreement with the value 19.8 kcal found by thermal measurements.

NMR of “trans” and “gauche” rotamers of tetrafluorohydrazine

Abstract The F 19 NMR spectrum of the “ trans ” and “ gauche ” rotamers of N 2 F 4 has been analyzed and the “ gauche ” form found to best be represented by the AA′ BB′ system. The parameters of “ gauche ” N 2 F 4 are: δ = 688.6 cps, J AB ± 489.6 cps, J AB ′ = ±13.4 cps, J AA ′ = ±58.8 cps and J BB ′ = ±109.0 cps.