Bis(citrato)germanate complexes with organic cations: Crystal structure of (HNic)2[Ge(HCit)2]•3H2O

Bis(citrato)germanate complexes with organic cations—protonated nicotinic acid ((HNic)2[Ge(HCit)2]·3H2O (I)), protonated nicotinamide ((HNad)2[Ge(HCit)2]·3H2O (II)), and protonated isonicotinic acid hydrazide ((HInd)2[Ge(HCit)2] (III)) (H4Cit is citric acid)—have been synthesized for the first time. Complexes I–III were studied by chemical and X-ray powder diffraction methods, thermal analysis, and IR spectroscopy. The X-ray diffraction study of complex I was carried out. The crystals are monoclinic, a = 10.931(7) Å, b = 11.420(1) Å, c = 23.188(6) Å, β = 101.54(4)°, V = 2836(2) Å3, z = 4, space group P21/n, R = 0.0334 for 1959 reflections with I > 2σ(I). In the complex anion [Ge(HCit)2]2− of the molecule of I, the coordination polyhedron of the Ge atom is a distorted octahedron formed by six O atoms of two tridentate chelating ligands HCit3− (Ge-O, 1.806–1.957 Å). In the structure of I, anions, cations, and water molecules are linked together by an intricate system of hydrogen bonds.