Ammonium and potassium citratogermanates(IV): Synthesis, chemical compositions, and structures. the crystal structures of (NH4)[Ge(OH) (H2Cit)2] · H2O and K 4[Ge(HCit)2(H2Cit)] · 3H2O

Methods for the synthesis of ammonium citratogermanate (NH4)[Ge(OH)(H2Cit)2] · H2O (I) and potassium citratogermanate (K4[Ge(HCit)2(H2Cit)] · 3H2O (II), where H4Cit is citric acid) in aqueous MeCN were developed. The individuality, chemical composition, and thermal stability of complexes I and II were proved by elemental analysis, thermogravimetry, and IR spectroscopy. According to X-ray diffraction data, the coordination numbers of the Ge atoms are 5 and 6 and their coordination polyhedra are a square pyramid and an octahedron in complexes I and II, respectively. In both complexes, the Ge atom coordinates the deprotonated OH group and the α-carboxyl group of the ligands HnCit4−n to form five-membered chelate rings. Hydrogen bonds in I as well as potassium cations in II serve to unite these complexes into frameworks.