The solid-state ~(19)F NMR spectrum of [N(CH_3)_4][IO_2F_2],a vibrational study of [N(CH_3)_4][IO_3] and [N(CH_3)_4][IO_3] centre dot 2H_2O,and the X-ray crystal structures of [N(CH_3)_4] [IO_2F_2] and [N(CH_3)_4][IO_3]

摘要

The salts,[N(CH_3)_4][IO_2F_2] and [N(CH_3)_4][IO_3],were characterized by single-crystal X-ray diffraction.Both salts crystallize in centrosym-metric space groups:[N(CH_3)_4][IO_3],Pnma,a=13.4330(8) A,b=7.0909(4) A,c=8.5035(5) A,V=809.98(8) A~3,Z=4,and R=0.0199 at-152 deg C;[N(CH_3)_4][IO_2F_2],C2/m,a=10.7047(5) A,b=14.6386(8) A,c=5.3082(3) A,beta=92.561(3) V=830.97(8) A~3,Z=4,and R=0.0260 at -152 deg C.The ~(19)F NMR spectrum of powdered,microcrystalline [N(CH_3)_4] [IO_2F_2] showed broad lines that arise from residual dipolar coupling and result from the large quadrupole moment of the ~(127)I nucleus.This represents the first example of quadrupolar effects from ~(127)I manifested in the NMR spectrum of a spin-1/2 nuclide.The ~(19)F lineshape was simulated using ~1J(~(127)I-~(19)F)=-1000 Hz and a ~(127)I quadrupolar coupling constant of 5000 MHz as preliminary values.Raman spectroscopic data are reported for the first time for [N(CH_3)_4] [IO_3] and [N(CH_3)_4] [IO_3] centre dot 2H_2O.The prior conflicting vibrational assignments for the IO_3~-anion have been resolved and are supported by electronic structure calculations.