Metallophilic (metal-metal) interactions are weak interactions between closed-shell (d10, s2) or pseudo-closed-shell (d8) metal cations. This type of interaction is generally believed to be responsible for various intriguing structures, luminescence, catalysis and magnetism. To gain a better understanding of metallophilic interactions, both experimental and computational investigations have been carried out in this thesis. Chapter 1 gave an up-to-date literature review on the definition, significance, and methods of estimating metallophilic interactions. The disputed nature and strength of metallophilic interactions encouraged us to further understand them. Chapter 2 focused on aurophilic interactions between AuI cations. Aurophilic interactions were observed in the solid state, but not well expressed in solution. Further experimental and computational results suggested that the strength of aurophilic interactions were weaker than electrostatic interactions. The nature of aurophilic interactions arose from orbital interactions rather than dispersion. Chapter 3 presented the study of metallophilic interactions between group 10 metal centres, including PtII-PtII, PdII-PdII and NiII-NiII. A series of cyclometalated square-planar metal complexes with different metals or substituents were prepared. PtII-PtII interactions were found to be stronger than PdII-PdII and NiII-NiII interactions. The dimerization constants of the Pt-containing complexes increased in line with increasing electron-withdrawing ability. Chapter 4 investigated the solvent-induced and thermally dependent colour changes of the Pt-containing complexes synthesised in chapter 3. Metallophilic interactions were proposed to be important in influencing the luminescence properties.

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This thesis is concerned with applications of modern solid-state NMR spectroscopy. Investigations of three quite different types are undertaken, each of which attempt to advance knowledge in the fields of chemistry and NMR. The goal of each project is to obtain insight into the effects of chemical environment, in particular bonding, on the NMR observables. Carbon-13 and nitrogen-15 solid-state nuclear magnetic resonance has been used to study solid samples containing the dicyanoaurate(I) anion, [Au(CN)2]-, with n-butylammonium, potassium, and thallium counterions. Differences in Au-Tl metallophilic bonding are shown to cause a difference in the isotropic cyanide carbon-13 chemical shift of up to 15.7 ppm, while differences in Au-Au aurophilic bonding are found to be responsible for a change of up to 5.9 ppm. Disordered polymeric gold(I) monocyanide was also investigated, and a range of 7+-2% to 25+-5% of the AuCN chains are found to be "slipped" instead of aligned with the neighbouring chains at the metal position. An investigation of the chemical shift tensors of the 13C-labelled carbons in solid samples of Ph13C≡13CPh and (η2-Ph13C≡13CPh)Pt(PPh3)2·(C6H6) has also been carried out. Coordination of diphenylacetylene to platinum causes a change in the 13C chemical shift tensor orientation and a net increase in the isotropic chemical shift. The carbon chemical shift tensors in the platinum complex bear a striking similarity to those of the alkenyl-carbons in trans-Ph(H)C=C(H)Ph, and a theoretical discussion of these observations is presented. Each of the fundamental NMR interaction tensors (σ, J, D and V) may be decomposed into isotropic, symmetric, and antisymmetric components. Observations of all theoretically allowed components other than the antisymmetric portion of J (Janti) have previously been published. Andrew and Farnell's theory (Mol. Phys. 15, 157 (1968)) for the effects of Janti on NMR spectra has been extended to powdered samples, and methods for analyzing the resultant line shapes have been determined. Finally, the first reported experimental attempts to measure Janti are presented, and experimental proof that no elements of Janti(119Sn,119Sn) in hexa(p-tolyl)ditin are larger than 2900 Hz is given.

L’objectif de ce travail fut la synthèse de ligands fonctionnels de type N,N'-diphosphanyl-NHC (NHC = carbènes N-hétérocycliques) et l’étude de leur chimie de coordination. La synthèse du nouveau ligand tridentate, stable et rigide, N,N'-diphosphanyl-imidazol-2-ylidene a permis des études expérimentales et théoriques et l’accès à des complexes mono-, di-, tri-, penta-, et hexanucléaires des métaux du groupe 11 (Cu, Ag et Au) originaux et aux propriétés structurales uniques. Les complexes mono- et dinucléaires avec un ou deux atomes de phosphore libres ont permis d’accéder à des complexes hétérotrinucléaires à interactions d10-d10 qui sont luminescents. La transmétallation partielle ou totale des complexes homotrinucléaires de Cu ou d’Ag avec des réactifs contenant du Pd(0) ont conduit à des complexes hétérotrinucléaires à interactions d10-d10. En plus de son comportement pontant, ce ligand peut se agir en chélate dans des complexes du palladium et du chrome. Dans le cas du Cr(III), ils montrent une activité catalytique en oligomérisation de l’éthylène supérieure à celle des complexes du Cr(II) et conduisent principalement à des oligomères. / The purpose of this work was the synthesis of N,N'-diphosphanyl-functionalized NHC ligands andtheir coordination chemistry. The novel stable and rigid tridentate N,N'-diphosphanyl-imidazol-2-ylidene was synthesized and experimental and computational information on its stability weregained. It served as a unique platform for the synthesis of novel mono-, di-, tri-, penta-, hexanuclear complexes with the coinage metals (Cu, Ag and Au), exhibiting rare structural features. The mono- and dinuclear complexes with one or two dangling P-donors provided rational access to heterotrinuclear complexes. All these coinage metal complexes have short metal-metalseparations, indicating the presence of d10-d10 interactions, and display excellent luminescentproperties. Partial or complete transmetallation of the homotrinuclear Cu or Ag complexes withPd(0) precursors led to hetero-trinuclear complexes with d10-d10 interactions. In addition to itsbridging behavior, this ligand also showed its chelating behavior in Pd or Cr(III) complexes. Thelatter displayed superior performance in ethylene oligomerization than the Cr(II) complexes andgave mostly oligomers.