Supramolecular salts containing the anionic [Ge(C(2)O(4))(3)](2-) complex and heteroaromatic amines

Abstract

The crystalline compounds (Hbipy)2[Ge(C2O4)3] (1) and (Hphen)2[Ge(C2O4)3] 2(H2O) (2) [Hbipy+ is the 2,20-bipyridinium cation (C10H9N2), and Hphen+ is the 1,100-phenathrolinium cation (C12H9N2)] were isolated from mild hydrothermal syntheses and their structures were elucidated from single-crystal X-ray diffraction. The two compounds were further characterised by vibrational spectroscopy (FT-IR and FT-Raman), thermogravimetric analysis (TGA) and CHN elemental composition. Compounds 1 and 2 comprise the tris(oxalato-O,O0)germanate dianion complex, [Ge(C2O4)3]2 , which co-crystallises with Hbipy+ (in 1), or Hphen+ and water molecules (in 2). In 1, the germanium oxalate anionic complex, [Ge(C2O4)3]2 , and the Hbipy+ organic residues interact mutually via N–H O hydrogen bonding interactions, leading to supramolecular discrete hydrogen-bonded units which are further interconnected via p–p stacking. Compound 2, on the other hand, exhibits a more complex hydrogen bonding network due to the presence of the water molecules of crystallisation which, along with p–p stacking between neighbouring Hphen+ residues, mediate the crystal packing.