A synthetic molybdenum hydroxylase compound that cleaves C-H bonds by hydride abstraction

Le résumé fourni par la source

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 bio-inspired H⁻ abstraction pathway. A cis -dioxomolybdenum(VI) complex supported by a tetradentate [N 2 S 2 ] 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 [N 2 O 2 ] 2- analogue showing no reactivity. Notably, the reduced Mo IV =O product undergoes biomimetic re-oxidation to cis -O=Mo VI =O using H₂O as the oxygen-atom source in the presence of a PCET acceptor (O 2 or 1,4-benzoquinone). Overall, this system establishes a bio-inspired H⁻ abstraction paradigm for C–H activation and charts the reaction pathways needed for catalytic turnover.

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