[(TpMe,Ph)2Zn2(H3O2)]ClO4: a new H3O2 species relevant to zinc proteinases

A dinuclear zinc(II) complex has been isolated from the reaction of Zn(ClO4)2 with TpMe,Ph (TpMe,Ph=hydrotris(5,3-methylphenylpyrazolyl)borate). We have characterized this species by a high quality X-ray crystal structure (R1=3.83%), and found it to contain a H3O2 bridge. We discuss the relevance of this structure in terms of hydrolytic zinc enzymes that utilize hydrogen-bond stabilized water nucleophiles to perform peptide bond cleavage.