Synthesis and structure of a mixed-valence tetramolybdate containing a binucleating diazene ligand

Reaction of MoO2Cl2(dmf)2(dmf = dimethylformamide) with 1,4-dihydrazinophthalazine (dhphH6) gives [Et3NH]2[Mo4O11dhphH2], which is shown by an X-ray crystal structure analysis to be a binuclear, oxo-bridged, formally MoIV, diazene complex with bridging molybdate groups; upon acidification the complex reversibly converts into a MoVI derivative of the fully protonated, parent hydrazine.