The active site of nitrile hydratase contains a low-spin Fe(III) or non-corrin Co(III) with S-oxygenated cysteine donors resulting in a facial sulfenate (RSO-), sulfinate (RSO2-), substrate coordination environment. In our pursuit of bio-inspired functional mimics, we prepared a low-spin (N2S3)RuIIPPh3 dithiolate complex capable of reproducing the facial arrangement of the S2X donors. By fixing the O2 quantity and the reaction time, conditions were optimized to reproducibly obtain high yields of the mono-sulfinate (RS-/RSO2-), sulfenate/sulfinate (RSO-/RSO2-), and bis-sulfinate (RSO2-/RSO2-) derivatives without the need for O-atom transfer reagents or column chromatography. The complexes display a systematic increase in the Ru-PPh3 bond distance upon S-oxygenation suggesting enhanced lability of the PPh3 donor, which was confirmed through phosphine exchange studies. The dissociation of PPh3 in hot solvent also provides a coordination site for substrate binding allowing the complexes to effectively catalyze the hydrolysis of benzonitrile to benzamide in water.

Controlled sulfur oxygenation of a nitrile hydratase mimic: Enhanced ligand lability and hydrolysis activity

244th National Meeting (2012)

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