Low Coordinate Metal Complexes Supported by Bulky Bis(silyl)amides

Abstract

Low Coordinate Metal Complexes Supported by Bulky Bis(silyl)amides. A thesis submitted to The University of Manchester for the degree of Doctor of Philosophy in the Faculty of Science and Engineering. Silylamide chemistry is well developed throughout the entire Periodic Table due to the parent silylamines being commercially available, cheap and facile to synthesise. They have provided landmark complexes across the Periodic Table, including the first three-coordinate f- element complexes and the first near-linear f-element complexes. Herein, this work utilises bulky bis(silyl)amide ligands, in particular N†† {N(SiiPr3)2}, to prepare novel metal complexes with low coordination numbers. Chapter 1 reviews the literature on silylamide ligands as used on alkali metals, alkaline earth metals, transition metals and lanthanide metals, which sets the context of the thesis. In addition, chapter 1 also reviews bulky, monodentate ligands that have stabilised low coordination numbers for transition metals and lanthanide metals. In Chapter 2, group 1 complexes of several bulky silylamides including {N(SiiPr3)2}, {N(SitBuMe2)2}, {N(SiiPr3)(SitBuMe2)}, {N(SiiPr3)(SiMe3)} and {N(SitBuMe2)(SiMe3)} have been synthesised and structurally characterized, revealing variable bonding motifs based on the steric demands of the silylamide ligand. In Chapter 3, the N†† ligand was employed to stabilise the first two-coordinate Ln(III) complexes [Ln(N††)2][B(C6F5)4] (Ln = Sm, Tm, Yb), which were synthesized by halide abstraction of the heteroleptic three-coordinate precursors [Ln(N††)2(X)], (X = Cl, Ln = Sm, Tm; X = F, Ln = Yb) using [H(SiEt3)2][B(C6F5)4]. In Chapter 4, the three-coordinate heteroleptic Ln(III) complexes [Ln{N(SiiPr3)2}2(TEMPO)] (Ln = Tm, Yb) and [Ln(N††)2(TEMPO)][B(C6F5)4] (Ln = Sm, Tm, Yb) were synthesized. In Chapter 5, a series of homoleptic, two-coordinate 3d TM(I/II) (TM = Mn, Fe, Co) N†† complexes have been synthesized. These complexes will be characterized to assess how the 9 magnetic behaviour is affected by metal d-electron counts, oxidation states and the extent of 3dz2/4s mixing in a near-linear ligand field. Chapter 6 (also known as the Appendix) contains results that did not form a coherent story and are not published. The procedures and characterisation data for all complexes are given. In addition a book chapter is also included which reviews organometallic divalent lanthanide chemistry. The electronic structures and the magnetic behaviour of all complexes in Chapters 3-5 were investigated by EPR spectroscopy, magnetic studies and ab initio calculations.

Date of Award	1 Aug 2019
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Richard Winpenny (Supervisor) & David Mills (Supervisor)