Towards Structural-Functional Mimics of Acetylene Hydratase: Reversible Activation of Acetylene using a Biomimetic Tungsten Complex

The synthesis and characterization of a biomimetic system that can reversibly bind acetylene (ethyne) is reported. The system has been designed to mimic catalytic intermediates of the tungstoenzyme acetylene hydratase. The thiophenyloxazoline ligand S‐Phoz (2‐(4′,4′‐dimethyloxazolin‐2′‐yl)thiophenolate) is used to generate a bioinspired donor environment around the W center, facilitating the stabilization of W–acetylene adducts. The featured complexes [W(C2H2)(CO)(S‐Phoz)2] (2) and [WO(C2H2)(S‐Phoz)2] (3) are extremely rare from a synthetic and structural point of view as very little is known about W–C2H2 adducts. Upon exposure to visible light, 3 can release C2H2 from its coordination sphere to yield the 14‐electron species [WO(S‐Phoz)2] (4). Under light‐exclusion 4 re‐activates C2H2 making this the first fully characterized system for the reversible activation of acetylene. On and off relationship: A structural‐functional model has been designed to mimic the tungstoenzyme acetylene hydratase. The S‐Phoz ligand (2‐(4′,4′‐dimethyloxazolin‐2′‐yl)thiophenolate) is used to generate a bioinspired environment around the W center, which can stabilize W–C2H2 adducts and can also reversibly activate ethyne.