Chemistry of Re with N,N‘-Bis(2-pyridylmethyl)ethylenediamine (H₂pmen):  Hydrolysis, Dehydrogenation, and Ternary Complexes

A number of Re complexes with N,N‘-bis(2-pyridylmethyl)ethylenediamine (H₂pmen) have been made from [NH₄][ReO₄]. [ReOCl₂(H₂pmen)]Cl, [ReOCl(Hpmen)][ReO₄], and [ReO₂(H₂pmen)][ReO₄] are related by hydrolysis/HCl substitution. [ReOCl(Hpmen)][ReO₄] was structurally characterized and found to contain a water-stable amido−Re bond. Dehydrogenation of the N-donor ligand from each amine to imine with concomitant two-electron reduction of the Re center occurs readily in these systems. With suitable 3-hydroxy-4-pyrones, ternary complexes such as [Re^IIICl(ma)(C₁₄H₁₄N₄)][ReO₄]·CH₃OH, 5, were made from [NH₄][ReO₄], H₂pmen·4HCl and pyrones in one-pot syntheses. 5, a seven-coordinate Re^III complex, was structurally characterized.