[Hg(9-methyl-1-deazapurine)2](NO3)2 · H2O: a complex with a distorted hexagonal bipyramidal metal ion coordination sphere

Reaction of 9-methyl-1-deazapurine (9-MeDP) with Hg(CF3COO)2 in the presence of NaNO3 yields the title compound [Hg(9-MeDP)2](NO3)2 · H2O with the two 9-MeDP ligands bound to the metal ion via their N7 positions. The X-ray structure is reported: monoclinic, P21/c (no. 14), a = 5.4015(11), b = 20.467(4), c = 17.775(4) Å, β = 97.00(3)°, V = 1950.4(7) Å3, Z = 4. Hg is eight-coordinate with two trans-oriented Hg–N bonds (2.073(3) and 2.075(3) Å) and three nearly coplanar, bidentate nitrate moieties (Hg–O: 2.716(3)–2.985(4) Å), leading to a distorted hexagonal bipyramidal environment of the metal ion. Within this structure, the nitrate ions form a honeycomb-like chain structure with HgII being positioned inside the combs. This work represents the first report of such geometry for a transition metal ion surrounded by symmetrically bidentate nitrate ions. The corresponding nucleoside, 1-deazapurine 2′-deoxyribonucleoside, also forms a stable 2:1 complex with HgII, as was shown by 1H NMR spectroscopy, making it a potential candidate for incorporation into nucleic acids based on metal-mediated base pairs.