Synthesis and reactivity of divalent complexes of thulium, dysprosium, and neodymium

This dissertation describes research into the solution chemistry of divalent thulium, dysprosium, and neodymium. The area has been hindered by the lack of convenient starting materials and difficulties in handling these highly reactive divalent states. Ethereal solutions are light, temperature, oxygen and moisture sensitive. As a result, new methodology was created to synthesize lanthanide diiodides and procedures for handling the solutions were created and applied to survey the reaction chemistry in this area.; Initially, an investigation into the reactivity of thulium diiodide in organic synthesis was conducted. A novel in situ synthesis of TmI₂ was developed and used to study the coupling of alkyl iodides, bromides, and chlorides to ketones. Subsequently, the existence of the first molecular complex of Dy(II), DyI₂(DME)₃, was confirmed by X-ray crystallography and EDAX (Energy Dispersive Absorbance Spectroscopy) spectroscopy. The preliminary reactions demonstrate the power and scope of DyI₂ chemistry. Next, neodymium diiodide as a reagent in organic synthesis was explored. Neodymium is much cheaper than thulium, dysprosium and samarium, and is a stronger reducing agent. The utility of DyI₂ as a single component catalyst for the polymerization of isoprene to >98% cis-1,4-polyisoprene, an industrially important component of synthetic rubber was also described.; Reasons why it was initially so difficult to isolate any other Tm(II) complex were identified. TmI₂ in the presence of several organometallic ligands including pentamethylcyclopentadienyl, trimethylsilylcyclopentadienyl, and bis(trimethylsilyl)cyclopentadienyl, was found to react with the “inert” dinitrogen atmosphere.; In situ organodysprosium chemistry, the reaction of potassium bis(trimethylsilyl)cyclopentadienide with solvent-free DyI₂ in diethyl ether under an atmosphere of dinitrogen, also forms a reduced dinitrogen product. Organometallic Tm(II) complexes will also cleave diethyl ether.; Despite all these problems, it was possible to isolate of the first divalent organothulium complex, [C₅H₄(SiMe₃)] ₂Tm(THF). Crystallographic data show it to be isomorphous with the analogous ytterbium metallocene. This complex is believed to be the active species in the reduction of dinitrogen seen in Chapter 5, and constitutes the first fully characterized organothulium(II) species. The details for the solid-state synthesis of the solvent-free lanthanide diiodides are also described. The new methodology allows for the rapid production of multi-gram quantities of solvent-free lanthanide diiodides of Tm, Dy and Nd.