Date of Award

2017

Publication Type

Doctoral Thesis

Degree Name

Ph.D.

Department

Chemistry and Biochemistry

Keywords

Ligand; Low oxidation state; Low valent; Main Group Chemistry; Phosphorus; Triphosphenium

Supervisor

Macdonald, Charles

Rights

info:eu-repo/semantics/openAccess

Abstract

P+ transfer was achieved through ligand metathesis and oxidative addition reactions from an air- and moisture- stable triphosphenium cation, [dppeP][Br], to generate new molecules containing low valent phosphorus. This protocol, involving the transfer of P+, allows for the generation of these molecules without the use of harsh reagents, in high yields, and is often achieved in few synthetic steps. This protocol has allowed for the synthesis of new phosphorus containing oligomers, including a phosphorus-rich analogue to polyphosphazenes, which can act as a bidentate donor to late transition metals. Further, neutral triphosphenium analogues can be synthesized through ligand exchange reactions, leading to the production of two different multidentate donors. These molecules, which feature a low oxidation state phosphorus center have the ability to act as multidentate donors. The molecule [Cp(PPh2)3P] selectively generates complexes at the phosphine fragment on the backbone of the ligand, and this reactivity is rationalized based on computational studies. In contrast, the molecule [tBuCp(PPh2)2P] generates multimetallic complexes with metal carbonyls through either the PI fragment or the Cp and P(I) fragments simultaneously. The reactivity of this ligand changes dramatically with mid- and late- transition metals, which insert into the P-P bond of the triphosphenium fragment. Finally, the addition of disulfide based ligands to [dppeP][Br] result in the oxidative transfer of the P(I) moiety, generating trithiophosphines in one step. We postulate that the formation of these molecules proceeds through a P(II) dimer, to which an additional fragment of disulfide adds, to generate the final thiophosphines.

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