Theoretical Evidence for Two New Intermediate Xenon Species: Xenon Azide Fluoride, FXe(N(3)), and Xenon Isocyanate Fluoride, FXe(NCO).
The reaction behavior of xenon difluoride, XeF(2), toward HN(3), NaN(3), and NaOCN was investigated in H(2)O, aHF (anhydrous HF), and SO(2)ClF solution. The analysis of the final reaction products (XeF(2) + HN(3) (NaN(3)) in H(2)O --> HF, N(2), N(2)O, Xe; XeF(2) + HN(3) in aHF --> N(2), Xe, N(2)F(2); XeF(2) + HOCN (NaOCN) in H(2)O --> HF, N(2), N(2)O, NH(3), CO(2), Xe) indicated the intermediate formation of FXe(N(3)) and FXe(NCO) and revealed different reaction mechanisms for both compounds. Both intermediates, FXe(N(3)) and FXe(NCO), were studied on the basis of ab initio computations at HF and correlated MP2 levels using a quasirelativistic LANL2DZ pseudopotential for Xe. Both were shown to possess stable minima at HF and MP2 levels (no imaginary frequencies) with the following structural parameters (MP2/LANL2DZ). FXe(N(3)): C(s)(); d(F-Xe) = 2.051, d(Xe-N1) = 2.318, d(N1-N2) = 1.241, d(N2-N3) = 1.180 Å; angle(FXeN1) = 178.1, angle(XeN1N2) = 112.2, angle(N1N2N3) = 174.7 degrees. FXe(NCO): C(s)(); d(F-Xe) = 2.024, d(Xe-N) = 2.206, d(N-C) = 1.194, d(C-N) = 1.231 Å; angle(FXeN) = 178.7, angle(XeNC) = 125.4, angle(NCO) = 174.2 degrees. The experimentally unobserved cyanate isomer, FXe(OCN), was calculated to be higher in energy than the isocyanate isomer FXe(NCO): DeltaE = 19.8 (HF), 18.3 (MP2) kcal mol(-)(1).
Schulz
Axel
A
Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K.
Klapötke
Thomas M.
TM