Doctor of Philosophy
Joe B. Gilroy
This thesis describes the investigation of a novel strategy for the synthesis of metal-containing small molecules, polymers, and nanomaterials. In this context, a new family of air-stable, homo- and heterometallic primary, secondary, and tertiary phosphines were prepared via the radical-initiated hydrophosphination reaction of PH3 with vinylferrocene and/or vinylruthenocene. The full characterization of the phosphines confirmed their targeted structures and proved that the properties of the starting metallocenes are reflected in those of the resulting phosphines.
To study the coordination behavior of this family of phosphines, primary, secondary, and tertiary ethylferrocene phosphines were reacted with Group 6 metal carbonyl adducts [M(CO)5•THF; where M: Cr, Mo, and W] to generate the corresponding metal complexes. The successful coordination of all three phosphines to M(CO)5 and their purity were confirmed by several characterization methods, such as multinuclear NMR, FT-IR, and UV-vis absorption spectroscopy, cyclic voltammetry (CV), and elemental analysis. FT-IR spectroscopy studies revealed that ethylferrocene substituents act as electron-donating groups and that the σ donating ability of the phosphines were lower than that of PEt3 and higher than that of PPh3.
To realize highly metallized polymers, two phosphorous-containing frameworks were targeted: quaternary phosphonium polyelectrolytes and tertiary phosphine polymers. The first iron-containing phosphonium monomer was synthesized by the quaternization reaction of tertiary ethylferrocene phosphine with 3-chloro-1-propanol followed by an esterification reaction with methacryloyl chloride and a salt metathesis reaction with NaOTf. In addition, four styrenic phosphonium monomers were synthesized by the quaternization reaction of 4-vinylbenzyl chloride with the tertiary ethylmetallocene phosphines (where Fe/Ru: 3/0, 2/1, 1/2, 0/3) before their counter-anion was exchanged with triflate. All five monomers were polymerized in the presence of azobisisobutyronitrile (AIBN) and carefully purified. Analysis of the polymers with methods including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC) confirmed their macromolecular nature. The pyrolysis of thin films of the phosphonium polymers, under an inert atmosphere, afforded highly metallized crystalline nanomaterials that were characterized with techniques such as scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX).
Finally, the hydrophosphination reaction of 3-buten-1-ol with a secondary ferrocene- and ruthenocene-containing phosphine followed by a N,N'-dicyclohexylcarbodiimide (DCC) coupling reaction with 4-vinyl benzoic acid afforded a tertiary phosphine monomer which was polymerized, in the presence of AIBN, and yielded a heterobimetallic tertiary phosphine polymer. The phosphine polymer was reacted with photogenerated W(CO)5•THF to produce the first example of a heterotrimetallic polymer. The proposed structure of the resulting polymers and their purity were confirmed by methods such as multinuclear NMR, FT-IR, and UV-vis absorption spectroscopy, CV, DSC, TGA, and GPC. The complete coordination of all phosphorous centres in the tertiary phosphine polymer to W(CO)5 was confirmed by 31P NMR spectroscopy and FT-IR studies, where the coordinated-tertiary phosphine polymer gave rise to three diagnostic absorption bands due to CO stretching modes from W(CO)5 moieties.
Rabiee Kenaree, Amir, "Synthesis of Metal-Containing Phosphines and Their Use in Coordination, Polymer, and Materials Chemistry" (2016). Electronic Thesis and Dissertation Repository. 4302.