Theoretical investigation on the conformational space of perfluorohydroxylamine, F2NOF

The conformational space of perfluorohydroxylamine, F2NOF, is studied using the CCSD/aug-cc-pVDZ level of theory. It is found that the lowest-energy form of F2NOF exhibits an anti conformation. This finding agrees with other theoretical studies, which indicate that the anti form is the most stable conformation upon H2NOH fluorination on oxygen and/or nitrogen takes place [L. Radom, W.J. Hehre, J.A. Pople, J. Am. Chem. Soc. 94 (1972) 2371]. On the other hand, the present result is in complete disagreement with recent theoretical studies, in which the syn form of F2NOF is proposed to be the minimum-energy conformation [P. Antoniotti, F. Grandinetti, Chem. Phys. Lett. 366 (2002) 676]. An NBO analysis at the B3LYP/aug-cc-pVDZ level of theory reveals that the interaction between the nitrogen lone pair and the OF antibond on one hand, and interactions between one oxygen lone pair and the two NF antibonds on the other hand, are responsible for the deep minimum, in which the anti conformer lies. Only those stabilizing interactions originated in the abovementioned oxygen lone pair accounts for the very flat region, in which the syn form is located.