First complex of the monoprotonated trioxodinitrate anion: synthesis and characterization of [Hg2(HN2O3)2(NO3)(Ph2PNHPPh2)2]

The reaction of Hg(NO3)2PH2Owith bis(diphenylphosphino)amine, Ph2PNHPPh2 (dppam), produces [Hg2(HN2O3)2(NO3)2(dppam)2] (1), which is the first complex containing the monoprotonated trioxodinitrate anion. 1 has been fully characterized by an X-ray structure analysis, NMR spectroscopy (199Hg{1H}, 31P{1H}, 1H), FAB mass spectrometry, IR spectroscopy, elemental analysis and melting point. 1 is the unique example of a face-to-face complex of five-coordinate Hg(II) centres with dppam including the first structural characterization of a rare tautomer of the monoprotonated trioxodinitrate anion.