Coordination of 2,3-diaminopyridine in the diamidopyridinium mode to the ReO3+ core

2,3-Diaminopyridine (H₂dap) reacts with (n-Bu₄N)[ReOCl₄] to form an air-stable salt of composition [ReO(Hdap)₂]Cl·2H₂O. Spectroscopic studies and X-ray crystallography show that Hdap is coordinated in the monoanionic diamidopyridinium mode to the oxorhenium(V) center. The protonation of the pyridyl nitrogens and the charge on the complex have no influence on the bond lengths and angles, with the rhenium(V)–oxo and average Re–NH bond lengths equal to 1.688(4) and 1.993(5) Å, respectively.