M. E. Grice

Energetics of HF Elimination and N-F Bond Cleavage in Some Difluoramines and Gem-Nitro/Difluoramines.

Abstract We have shown, through density functional calculations (Becke exchange/Lee, Yang and Parr correlation functional, 6-31G ∗∗ basis set) that the elimination of HF from H 3 CNF 2 is thermodynamically favored, ΔG (298.15 K ) = −29kcal mol −1 , but has a relatively high activation barrier, ΔG‡(298.15 K) = 38 kcal mol −1 . The NF dissociation energy, ΔE N  F , is found to be 69 kcal mol −1 . Introduction of a nitro group, giving H 2 C(NO 2 )NF 2 , produces only small changes in these values: ΔG (298.15 K ) = −28 kcal mol −1 ; ΔG‡(298.15 K) = 36 kcal mol −1 ; ΔE N  F = 66 kcal mol −1 . Replacement of all alpha hydrogens by methyl groups increases the NF dissociation energies slightly ( −1 ). These substituent effects are interpreted in terms of geminal interactions.