MOLECULAR-STRUCTURE OF FLUORINE NITRATE - DANGEROUS FOR EXPERIMENT AND THEORY

A general valence force field for FONO2 is deriverd from Ne-matrix inf rared spectra together with N-15 and O-18 isotopic shifts. A gas elect ron diffraction study results in a planar structure with the following geometric parameters (r(a) distances and L(a) angles with 3 sigma unc ertainties): N=O = 1.184(2) Angstrom, N-O = 1.507(4) Angstrom, O-F = 1 .409(5) Angstrom, O-N=O-c = 117.1(9)degrees, O-N=O-t = 108.4(18)degree s, O-c=N=O-t = 134.5(21)degrees, and N-O-F = 106.0(11)degrees. O(c)and O-t, are the oxygen atoms cis and trans to the O-F bond. The N-O sing le bond in fluorine nitrate is ca. 0.1 Angstrom longer than those in n itric acid and methyl nitrate. Various ab initio calculations predict rather different N-O bond distances between 1.384 and 1.609 Angstrom, depending on the level of theory (HF, MP, CC, or CI) Local density fun ctional theory reproduces the experimental geometry perfectly. Nonloca l corrections, however,make the results drastically worse.