Utilizing Sulfoxide···Iodine Halogen Bonding for Cocrystallization

The propensity of a range of different sulfoxides and
sulfones
to cocrystallize with either 1,2- or 1,4-diiodotetrafluorobenzene,
via I···O=S
halogen bonding, was investigated. Cocrystallization occurred exclusively
with 1,4-diiodotetrafluorobenzene in either a 1:1 or 1:2 stoichiometry
of the organohalide and the sulfoxide, respectively, depending on
the sulfoxide used. It was found that the stoichiometry observed was
not necessarily related to whether the oxygen acts as a single halogen
bond acceptor or if it is bifurcated; with I···π
interactions observed in two of the cocrystals synthesized. Only those
cocrystals with a 1:2 stoichiometry exhibit C–H···O
hydrogen bonding in addition to I···O=S halogen bonding.
Examination of the Cambridge Structural Database shows that (i) the
I···O=S interaction is similar to other I···O
interactions, and (ii) the I···π interaction
is significant, with the distances in the two cocrystals among the
shortest known.