A Synthetic Molybdenum Hydroxylase Compound That Cleaves C-H Bonds by Hydride Abstraction

Molybdenum-dependent hydroxylases catalyze site-selective C-H hydroxylation reactions involving hydride abstraction pathways, yet no synthetic system has previously reproduced this reactivity. Here, we report a synthetic molybdenum hydroxylase that achieves C-H bond cleavage and hydroxylation through a bioinspired H^- abstraction pathway. A cis-dioxomolybdenum(VI) complex supported by a tetradentate [N₂S₂]^2- ligand reacts with hydridic benzimidazoline substrates to effect net C-H hydroxylation, yielding the corresponding alcohol products (observed as tautomeric amides) and a Mo^IV═O species. Mechanistic experiments and density functional theory calculations support a pathway involving hydride transfer to cis-O═Mo^VI═O to generate a O═Mo^IV-OH intermediate capable of carbocation/hydroxide rebound. The transformation is reversible and dependent on a sulfur-rich ligand environment, with a [N₂O₂]^2- analogue showing no reactivity. Notably, the reduced Mo^IV═O product undergoes biomimetic reoxidation to cis-O═Mo^VI═O using H₂O as the oxygen-atom source in the presence of a PCET acceptor (O₂ or 1,4-benzoquinone). Overall, this system establishes a bioinspired H^- abstraction paradigm for C-H activation and charts the reaction pathways needed for catalytic turnover.