The molecular structure of N-fluorobis(trifluoromethanesulfonyl)imide, NF(SO(2)CF(3))(2), as studied in the gas phase by electron diffraction restrained by ab initio calculations.

The structure of N-fluorobis(trifluoromethylsulfonyl)imide, prepared by a relatively safe and easy method, has been determined by gas-phase electron diffraction (GED), employing the SARACEN method, with flexible restraints based on the MP2/6-311G* structure, and by X-ray crystallography at 150 K. The strongly electron-withdrawing CF(3) and SO(2)CF(3) groups make the C-S and N-S distances long, averaging 187.7(3) and 171.7(3) pm, respectively, in the gas phase. The gas consists of two conformers, one (75%) with a CF(3) group on each side of the SNS plane, one anti-periplanar and one syn-periplanar to the further N-S bond (ap, sp), and the other with both CF(3) groups on the same side, i.e. denoted ap, ap. These conformers have very different SNS angles, 126.9(9) degrees and 117.1(17) degrees respectively. In the crystal all molecules have the ap, sp conformation, with parameters similar to those found for this conformer in the gas phase.