Synthesis, properties, and crystal structure of diphenylguanidinium bis(citrato)germanate hydrate (HDphg)2[Ge(HCit)2] · 1.08H2O

Diphenylguanidinium bis(citrato)germanate hydrate (HDphg)2[Ge(HCit)2] · 1.08H2O (I) was prepared for the first time (H4Cit is citric acid, Dphg is diphenylguanidine). The composition of I was determined using elemental analysis and thermogravimetry; the coordination sites of H4Cit and the protonation sites of Dphg were identified by IR spectroscopy. Compound I was studied by X-ray diffraction. The crystals are monoclinic, a = 11.179(2) Å, b = 7.6081(15) Å, c = 23.529(5) Å, β = 95.38(3)°, V = 1992.3(7) Å3, Z = 2, space group P21/c, R = 0.0339 for 2498 reflections with I>2σ(I). In the [Ge(HCit)2]2− complex anion, the Ge atom is bond to a distorted octahedral array of six O atoms of the two tridentate chelating HCit3− ligands (Ge-O, 1.8045–1.9555 Å). In the crystal of I, the anions and cations are combined into layers by a system of hydrogen bonds.