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Auto-ionization in Lutetium Iodide Complexes:  Effect of the Ionic Radius on Lanthanide−Iodide Binding

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posted on 2004-02-09, 00:00 authored by Garth R. Giesbrecht, John C. Gordon, David L. Clark, Brian L. Scott
Reaction of lutetium metal with 1.5 equiv of elemental iodine in 2-propanol leads to the isolation of LuI3(HOiPr)4 (1). An X-ray crystal structure reveals an ionic structure with well-separated [LuI2(HOiPr)4] cations and [I] anions. Dissolution of 1 in pyridine generates the unusual alkoxide species [LuI(OiPr)(py)5][I] (2) with the elimination of HI. An X-ray crystal structure of 2 confirmed the ionic nature of the compound, with the cationic portion of the complex exhibiting a seven-coordinated lutetium center with trans-disposed iodo and alkoxide ligands and five pyridine molecules equally displaced within the equatorial plane. Exposure of 2 to iodotrimethylsilane yields the expected triiodide species [LuI2(py)5][I] (3), which may also be prepared by refluxing commercially available LuI3 in THF, followed by crystallization from a THF/pyridine mixture. The solid-state structure of 3 is similar to that of 2, with the alkoxide ligand having been replaced by an iodide. The formation of ionic structures 13 as opposed to the higher-coordinated neutral species may be traced to the small lutetium center and the presence of relatively strong Lewis bases within the coordination sphere of the metal.

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