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Updated: Apr 2, 2026
Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging
Published on: July 21, 2011
Amidophenolate Lanthanide Complexes and Their Multielectron Reactivity
Landon O King1, Kelly L Gullett1, Andrew W Mitchell1
1H. C. Brown Laboratory, James Tarpo, Jr and Margaret Tarpo Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States.
None:
A general approach to achieving multielectron reactivity with redox-restricted lanthanide complexes is to utilize redox-active ligands, which allow for facile electron transfer at the ligand throughout a reaction. Our group has successfully utilized an iminoquinone (iq) ligand capable of undergoing two-electron reduction events to form an iminosemiquinone (isq) and an amidophenolate (ap), respectively, on a variety of metals to achieve multielectron reactivity. Here, we report the synthesis and characterization of two tris-ligated lanthanide complexes, [Nd(ap)3]K3 (Nd-L3) and [Yb(ap)3]K3 (Yb-L3), and a bis-ligated complex, [Yb(ap)2]K (Yb-L2). Compounds Nd-L3 and Yb-L3 were treated with elemental sulfur. In the presence of S8, rapid ligand oxidation was observed, leading to the dissociation of a potassium iminosemiquinone ligand and the formation of a S72- chain. Alternatively, when S8 was added to Yb-L2, ligand oxidation was noted with the formation of a twist-boat metallocycle, [Yb(S5)(isq)2](K18c6) (Yb-S5). All complexes were fully characterized by using 1H NMR spectroscopy, electronic absorption spectroscopy, and X-ray crystallography to fully assign ligand oxidation states.
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