Synthesis and Reactivity of a Bioinspired Molybdenum(IV) Acetylene Complex

[Image: see text] The isolation of a molybdenum(IV) acetylene (C(2)H(2)) complex containing two bioinspired 6-methylpyridine-2-thiolate ligands is reported. The synthesis can be performed either by oxidation of a molybdenum(II) C(2)H(2) complex or by substitution of a coordinated PMe(3) by C(2)H(2) on a molybdenum(IV) center. Both C(2)H(2) complexes were characterized by spectroscopic means as well as by single-crystal X-ray diffraction. Furthermore, the reactivity of the coordinated C(2)H(2) was investigated with regard to acetylene hydratase, one of two enzymes that accept C(2)H(2) as a substrate. While the reaction with water resulted in the vinylation of the pyridine-2-thiolate ligands, an intermolecular nucleophilic attack on the coordinated C(2)H(2) with the soft nucleophile PMe(3) was observed to give a cationic ethenyl complex. A comparison with the tungsten analogues revealed less tightly bound C(2)H(2) in the molybdenum variant, which, however, shows a higher reactivity toward nucleophiles.