Hypervalent Iodine Compounds with Tetrazole Ligands

Hypervalent iodine
compounds with two I–N bonds, containing
5-substituted tetrazoles as the ligands PhI­(N4CR)2 (R = CH3, C6H5, and 4-CH3C6H4), were synthesized from PhI­(O2CCF3)2 or PhICl2 and the corresponding
tetrazole potassium salts. Alternatively, PhIO was reacted with the
free tetrazoles, and the reactions afforded either PhI­(N4CR)2 or, in most cases, μ-oxo- or oligomeric compounds
with several I and O atoms in the backbone and two terminal tetrazole
groups. The isolated compounds were reasonably stable in the solid
state as well as in solution at room temperature but explosive at
elevated temperatures (135–180 °C depending on the structure).
The crystal structure of one representative compound (an oligomer
with three I atoms in the backbone and 5-phenyltetrazole end groups)
was solved and refined from synchrotron powder X-ray diffraction.
The novel compounds were characterized by cyclic voltammetry and were
found to be strong oxidants. In addition, they proved to be useful
reagents for the iodotetrazolylation of unsaturated compounds such
as styrene and cyclohexene and for the transfer of tetrazole groups
to N,N-dimethylaniline.