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Updated: Feb 18, 2026

Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging
Published on: July 21, 2011
A new lanthanum(III) complex containing acetyl-acetone and 1H-imidazole
Atsuya Koizumi1, Takuya Hasegawa2,3, Atsushi Itadani4
1Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-nocho, Niigata 950-2181, Japan.
Abstract:
In the title complex, di-aqua-(1H-imidazole-κN3)(nitrato-κ2O,O')bis-(4-oxo-pent-2-en-2-olato-κ2O,O')lanthanum(III), [La(C5H7O2)2(NO3)(C3H4N2)(H2O)2], the La atom is coordinated by eight O atoms of two acetyl-acetonate (acac) anions acting as bidentate ligands, two water mol-ecule as monodentate ligands, one nitrate anions as a bidentate ligand and one N atom of an imidazolate (ImH) molecule as a monodentate ligand. Thus, the coordination number of the La atom is nine in a monocapped square anti-prismatic polyhedron. There are three types of inter-molecular hydrogen bonds between ligands, the first involving nitrate-water O⋯H-O inter-actions running along the [001] direction, the second involving acac-water O⋯H-O inter-actions along the [010] direction and the third involving an Im-nitrate N-H⋯O inter-action along the [100] direction (five inter-actions of this type). Thus, an overall one-dimensional network structure is generated. The mol-ecular plane of an ImH molecule is almost parallel to that of a nitrate ligand, making an angle of only 6.04 (12)°. Inter-estingly, the ImH plane is nearly perpendicular to the planes of two neighbouring acac ligands.
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