H2S Generation from CS2 Hydrolysis at a Dinuclear Zinc(II) Site

The controlled generation of hydrogen sulfide (H 2 S) under biologically relevant conditions is of paramount importance due to therapeutic interests. Via exploring the reactivity of a structurally characterized phenolate-bridged dinuclear zinc(II)-aqua complex { L Zn II (OH 2 )} 2 (ClO 4 ) 2 ( 1a ) as a hydrolase model, we illustrate in this report that complex 1a readily hydrolyses CS 2 in the presence of Et 3 N to afford H 2 S. In contrast, penta-coordinated [Zn II ] sites in dinuclear {( L Zn II ) 2 (μ–X)}(ClO 4 ) complexes ( 7, X = OAc; 8, X = dimethylpyrazolyl) do not mediate CS 2 hydrolysis in the presence of externally added water and Et 3 N presumably due to the unavailability of a coordination site for water at the [Zn II ] centers. Moreover, [Zn II ]–OH sites present in the isolated tetranuclear zinc(II) complex {( L Zn II ) 2 (μ–OH)} 2 (ClO 4 ) 2 ( 4 ) react with CS 2, thereby suggesting that the [Zn II ]–OH site serves as the active nucleophile. Furthermore, mass spectrometric analyses on the reaction mixture consisting of 1a /Et 3 N and CS 2 suggest the involvement of zinc(II)–thiocarbonate ( 3a ) and COS species, thereby providing mechanistic insights into CS 2 hydrolysis mediated by the dinuclear [Zn II ] hydrolase model complex 1a .