Synthesis and Characteristics of the Dioxonium Salt Based on Tartratogermanate Acid. Crystal and Molecular Structure of (H_5O_2)[(H_2O)_2Ge(ì-Tart)_2Ge(OH)] ? 4H_2O

摘要

Tartratogermanate acid was obtained for the first time as the dioxonium complex (H_5O_2)[(H_2O)_2Ge(ì-Tart)_2Ge(OH)] ? 4H_2O (I) by the reaction of germanium tetrachloride with D-tartaric acid (H_4Tart) in 85% acetic acid. The complex was characterized by elemental analysis data, thermogravim-etry, and IR spectroscopy. X-ray diffraction analysis for I was performed. The crystals are orthorhombic, a = 15.862(3) A, b = 13.401(3) A, c = 8.6800(17) A, V= 1845.1(6) A~3, Z= 4, space group P2_I2_I2, R1= 0.0520 for 5152 reflections with /> 2a(7). Compound I is composed of the dimeric complex anions [(H_2O)_2Ge(ì-Tart)_2Ge(OH)]~-, dioxonium cations, and water molecules of crystallization. In the anion, the Ge(1) (CN = 6) and Ge(2) (CN = 5) atoms are linked by two chelating bridging fully deprotonated tartaric acid ligands through two carboxyl (average Ge-0,1.883(4) and 1.893(4) A, respectively) and two alcohol (average Ge-O, 1.859(4) and 1.779(4) A, respectively) oxygen atoms. The coordination polyhedron of Ge(1) is completed to a distorted octahedron by the oxygen atoms of two water molecules (Ge(l)-O(H_2O), 1.933(4) and 1.854(3) A). The Ge(2) coordination polyhedron is trigonal bipyramid. Its base is formed by two alcohol oxygen atoms of two bridging Tart~(4-) ligands and the oxygen atom of the terminal hydroxy group (Ge-O, 1.764(4) A). The axial positions are occupied by the carboxyl oxygen atoms of the Tart~(4-) ligands (the O(5)Ge(2)O(11), 176.84( 16)°). In the crystal, the structural units are combined by hydrogen bonds to a three-dimensional framework.