Synthesis of heavy cyanide analogs for the design of novel Prussian blue analogs

This thesis describes the chemistry of metal complexes of the cyaphide ion (C≡P−) and some of its derivatives, including their syntheses, properties, and reactivity.
Chapter 1. The chemistry of the cyaphide ion is introduced, starting with a cursory overview of its morecommon lighter congener, the cyanide ion, and its application in Prussian blue analogs. Next, the use ofthe isolobal analogy in describing fragments that are related to the cyanide and cyaphide ions is outlined. Finally, reported examples of the cyaphide ion in the chemical literature are surveyed, and their syntheses and characterization are discussed.
Chapter 2. Magnesium(II) cyaphide complexes are accessed by the reductive deoxygenation of siloxyphosphaalkynes using magnesium(I) reducing agents. The synthesis of these ionic cyaphide complexes is detailed, as is their characterization by multinuclear NMR spectroscopy, infrared and Raman spectroscopy, and single crystal X-ray crystallography. Theoretical insights into the properties of these complexes and the mechanism of their formation are also discussed.
Chapter 3. By analogy with classic Grignard reagents, magnesium(II) cyaphide complexes can be used to transfer the cyaphide ion to other metal centers. The synthesis of cyaphide-containing main group and transition metal complexes by cyaphide transfer is detailed. Where possible, these compounds are characterized by multinuclear NMR spectroscopy, infrared and Raman vibrational spectroscopy, and single crystal X-ray crystallography.
Chapter 4. The ligand properties of the cyaphide ion in the terminal, end-on κC coordination mode are determined in a comparative study of gold(I) IDipp complexes and group 9 DippPDI complexes. Using this approach, the σ donor and π acceptor properties of the cyaphido ligand are deconvoluted. In order to provide illustrative points of comparison, analogous metal complexes bearing various strong-field ligands are also synthesized and analyzed using the same approach.
Chapter 5. Hetero-multimetallic complexes of the cyaphide ion are synthesized by the reaction of a gold(I) cyaphide complex with electron-rich metal centers. These reactions are driven by the low-lying C≡P π* orbitals and result in side-on bridging cyaphide complexes, though reactivity at the Au−C bond can also occur for especially nucleophilic metals. These complexes are fully characterized, and the unusual chemical bonding in these species is discussed with the aid of theoretical calculations.
Chapter 6. Metal cyaphide complexes undergo 1,3-dipolar cycloaddition reactions with organic azides to afford metallo-triazaphospholes. These reactions proceed straightforwardly and regiospecifically in high yields under mild conditions, reminiscent of the archetypal “click” reaction between alkynes and azides. The resulting metallo-triazaphospholes remain reactive and can be carbon-functionalized to give otherwise difficult to access protio- and iodo- species.
Chapter 7. Metal cyaphide complexes are susceptible to oligomerization by formal cycloaddition reactions involving the reactive cyaphide C≡P π bonds to give highly charged, conjugated organophosphorus anions. The synthesis, characterization, and bonding of the oligomers and their monomer precursors are discussed herein. The factors that favor oligomerization are elucidated, providing a framework for understanding the stabilization of metal cyaphide complexes.
Chapter 8. The synthesis of highly stable iron(II) mono- and dicyaphide complexes is described. These are used as precursors to multimetallic iron complexes containing the cyaphide ion in end-on bridging coordination modes, structurally related to fragments of Prussian blue. The properties of these complexes are investigated using NMR and vibrational spectroscopy, X-ray crystallography, and cyclic voltammetry. Theoretical calculations provide insight into their electronic structures.

Keywords: cyaphide
transition metal
organophosphorus
phosphorus
inorganic
cyanide
organometallic
aromatic compounds
x-ray crystallography
chemistry
main group
Prussian blue
density functional theory
heterocyclic compounds
Advisor: Goicoechea, J