Syntheses and structural determination of mononuclear nine-coordinate (MnH)[GdIII(EDTA)(H2O)3] · 4H2O and 2D ladder-like binuclear nine-coordinate (MnH)2[Gd 2 III (H2TTHA)2] · 4H2O

Abstract

Two title rare earth metal coordination compounds, (MnH)[GdIII(Edta)(H2O)3] · 4H2O (I) and (MnH)2[Gd2III(H2Ttha)2] · 4H2O (II), where Mn = methylamine, H4Edta = ethylenediamine-N,N,N′,N′-tetraacetic acid, H6Ttha = triethylenetetramine-N,N,N′,N″,N′″,N′″-hexaacetic acid), have been successfully synthesized through direct heating reflux and characterized by FT-IR spectroscopy, thermal analysis and single-crystal X-ray diffraction techniques. In complex I, the Gd3+ ion is nine-coordinated by an Edta ligand and three water molecules, yielding a pseudo-monocapped square antiprismatic (MC-SAP) conformation. Complex I crystallizes in the orthorhombic crystal system with space group Fdd2. The cell dimensions are as follows: a = 19.5207(17), b = 35.387(3), c = 12.5118(11) A, and V = 8642.8(13) A3. The central Gd3+ ion of II is also ninecoordinate, forming tricapped trigonal prismatic (TC-TP) conformation with three amine nitrogen atoms and six oxygen atoms. Complex II crystallizes in the monoclinic crystal system with P2/c space group. The crystal data are as follows: a = 14.4301(13), b = 11.2400(11), c = 17.7102(16) A, β = 112.606(2)°, and V = 2651.8(4) A3. There retain outer-protonated and inner-protonated carboxyl oxygen atoms in the [Gd2III(H2Ttha)2]2− complex anion. In II, there are only one type of methylamine cation (MnH+) as the counter ion, which connects [Gd2III(H2Ttha)2]2− complex anions and lattice water molecules through hydrogen bonds, leading to the formation of 2D ladder-like layer structure.