Synthesis, properties, and molecular and crystal structure of hexaaquacopper(IV) bis(diaquacuprato-μ3-trihydroxyglutarato)germanate(IV) dihydrate [Cu(H2O)6][Ge(μ3-Thgl)2{Cu(H2O)2}2] · 2H2O

A procedure for the synthesis of the heteropolymetallic germanium(IV) and copper(II) complex with trihydroxyglutaric acid (H₅Thgl) Cu(H₂O)₆]Ge(μ₃-Thgl)₂{Cu(H₂O)₂}₂] · 2H₂O (I) was developed and the complex was isolated for the first time in the solid state. The product was characterized by elemental analysis, powder X-ray diffraction, thermogravimetry, and IR spectroscopy. Compound I was studied by X-ray crystallography. The crystals are monoclinic, a = 10.216(2)?, b = 12.272(3)?, c = 10.679(2)?, β = 93.13(3)°, V = 1336.9(5)?³, Z = 2, space group P2₁/n, R1 = 0.0261 for 3616 reflections with I > 2σ(I). Compound I is composed of bimetallic Ge(μ₃-Thgl)₂{Cu(H₂O)₂}₂]²⁻ anions, Cu(H₂O)₆]²⁺ cations, and water molecules of crystallization. In the centrosymmetric trinuclear complex anion, the Ge(1) atom is bound by two fully deprotonated bridging ligands to two Cu atoms. The Ge(1) atom is coordinated at distorted octahedron vertices by six hydroxyl oxygen atoms of two Thgl⁵⁻ ligands (average Ge(1)-O distance is 1.8874(13)?). The Cu coordination polyhedron in the anion is an extended square pyramid (4 + 1) formed by the bridging hydroxyl oxygen atom (Cu(1)-O(3), 2.0039(12) ?), two carboxyl oxygen atoms (average CU(1)-O distance is 1.9674(14)?) of two Thgl⁵⁻ ligands, and two water oxygen atoms in equatorial and axial positions (Cu(1)-O, 1.9761(13) and 2.3643(14)?, respectively). In the centrosymmetric cation, the Cu coordination polyhedron is an extended square bipyramid (4 + 2). The equatorial Cu-O bond length is 1.9428(14) ? (average), the axial Cu-O bond is elongated to 2.5151(14)?. The cations and anions are combined by H-bonds.