Invited Talk 21st International Conference on Biological Inorganic Chemistry 2025

Tungsten-dependent acetylene hydratase (AH) catalyzes the net-hydration reaction of acetylene to acetaldehyde. As the mechanism of this transformation is unclear, we develop biomimetic model chemistry as a useful tool for a better understanding.

In recent years we have developed strategies to selectively prepare tungsten acetylene compounds. A series of bidentate nitrogen sulfur donor ligands have been investigated allowing the elucidation of factors leading to selective acetylene coordination. The reactivity towards extra- and intramolecular nucleophilic attack is presented. Our studies reveal that tungsten(IV)-acetylene adducts readily react with nucleophiles to yield η¹-vinyl complexes, consistent with the expected behavior of two-electron donor alkyne ligands. By contrast, tungsten(II)-acetylene adducts exhibit unexpected reactivity, leading to the formation of stable carbyne complexes. This surprising outcome, which arises from a challenging 1,2-H shift, required detailed spectroscopic and computational studies.[1,2] Depending on the nucleophile, the intermediate vinyl species undergoes hydrolysis under formation of acetaldehyde (Figure 1).[3] The latter represents the first early transition metal compound known to facilitate acetylene hydration, making it a functional model of acetylene hydratase (AH). With our studies a new perspective on the AH mechanism arises including vinylation of a neighboring amino acid in the active site by acetylene insertion into a W−S or W−O bond before hydrolysis to acetaldehyde.

Figure 1.