The First Oxygen-Bonded Sulfenate Ion: Crystal and Molecular Structures of Bis(ethylenediamine)(2-pyridinesulfenato-<i>O</i>)cobalt(III) and Bis(ethylenediamine)(2-pyridinesulfinato-<i>O</i>)cobalt(III)

The first O-bonded sulfenate species [Co(en)2(py-SO-O)]2+ has been synthesized by isomerization of its S-bonded linkage isomer, [Co(en)2(pyridine-2-sulfenate-S]2+. The sulfenate ion in both forms is stabilized by coordination to the electropositive cobalt(III) ion. The driving force for the formation of the O-bonded sulfenate linkage isomer comes from the four to five membered ring expansion which accompanies the rearrangement. Crystal structures of the green O-sulfenate confirm the formulation and reveal varying amounts of a cocrystallized O-bonded sulfinate diastereomer. The cations have essentially identical structures except for the extra oxygen in the O-sulfinate. Differences in packing of cations and perchlorates give rise to two different structural types for the salts, corresponding to sulfenate-rich and sulfinate-rich phases.