Synthesis and reactivity of the 2-phosphaethynolate anion and phosphinecarboxamide

This thesis describes a novel synthesis of the 2-phosphaethynolate anion, [PCO]â, via reaction of the [P7]3â Zintl cluster with carbon monoxide. The ligand properties of this fundamental molecule have been probed and compared to common isoelectronic pseudohalides: cyanate and isocyanate. The first ambient-temperature synthesis of the heavier congener, [PCS]â, is also reported, and studies show that this anion can act as an ambidentate ligand. The cycloaddition chemistry of [PCO]â with heteroallenes afforded a range of novel anionic phosphorus-containing heterocycles. A collaborative study has shown that [PCO]â can act as a catalyst for the trimerisation of isocyanates, and potential intermediates in this catalytic cycle have been isolated. By analogy with Wöhler's historic synthesis of urea, the reaction of [PCO]â with ammonium salts yields phosphinecarboxamide. This unprecedented molecule is a rare example of an air-stable "user-friendly" primary phosphine, and its structure and ability to coordinate to metal centres were explored. It was found that this species has similar σ donor and π acceptor properties to phosphine, PH3. This reactivity has been extended to incorporate N-functionalised phosphinecarboxamides with a range of different functional groups. The Brønsted acidity, P-functionalisation and oxidation chemistry of these species was subsequently investigated to afford a diverse family of carbamoyl-bearing phosphides, phosphines and phosphine oxides. Some of these species have great potential to become industrially relevant molecules in the future. Preliminary results showing the generality of the reaction of [PCO]â with other protic nucleophiles are additionally presented.