Thesis (Ph. D.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Cette thèse décrits la synthèse et caractérisations de chaines métalliques étendues (EMACs:extended metal atom chains) construite à partir des ligands dipyridylamine (dpa) etdipyridylformamidinate (DpyF). Le Chapitre I fait une brève introduction sur les liaisons métalmétalet sur les chaines métalliques étendues. Le Chapitre II présente les propriétés de conversionde spin (SCO: spin crossover) d’une série d’EMACs de tris-cobalt de formule générale[Co3(dpa)4X2]. L’influence des ligands axiaux et de la symétrie des molécules a été examinée etcorrélée aux propriétés de conversion de spin. Le Chapitre III porte sur la résolutionénantiomérique et activité RX optique de l’EMAC tris-cobalt [Co3(dpa)4(MeCN)2]2+. Dans lechapitre IV, La chimie de coordination du ligand N,N’-di(2-pyridyl)formamidinate (DpyF), quiconduit à des complexes présentant des propriétés structurales and magnétiques remarquable,est explorée. Finalement, le chapitre V présente nos études préliminaires pour obtenir despolymères unidimensionnelles d’EMAC de tris-cobalt en utilisant des radicaux de type thiazyle. / This thesis describes the synthesis and characterizations of extended metal atom chains (EMACs)supported by dipyridylamine (dpa) and dipyridylformamidinate (DpyF) ligands. Chapter Iprovides a brief introduction to metal-metal bonds and extended metal atom chains. In Chapter IIspin crossover properties of series of tricobalt EMACs based on [Co3(dpa)4X2] motifs arepresented. The influence of the axial ligands and the symmetry of the molecule was examined andcorrelated with the SCO properties. Chapter III describes the enantiomeric resolution and X-rayoptical activity of tricobalt EMAC, [Co3(dpa)4(MeCN)2]2+. In chapter IV, the coordination chemistryof N,N’-di(2-pyridyl)formamidinate, (DpyF) is explored, a ligand which gives rise to complexeswith remarkable structural and magnetic properties Finally, chapter V presents our initial effortsto obtain one-dimensional coordination polymers of tricobalt EMAC using thiazyl radicals.

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.

Computational chemistry has gained interest as a characterization tool to predict photoluminescence, reactivity and structural properties of organic and transition metal complexes. With the rise of methods including relativity, these studies have been expanded to the accurate modeling of luminescence spectra of complexes with considerable spin-orbit splitting due to heavy metal centers as well as the reaction pathways for these complexes to produce natural products such as hydrogen gas. These advances have led to the synthesis and utility of more effective catalysis as well as the development of more effective organic light emitting diodes (OLEDs) through the incorporation of organometallic complexes as emitters instead of typical organic emitters. In terms of significant scientific advancement presented in this work is in relation to the discovery of significant spin-orbit splitting in a gold(I) alkylphosphine complex, where the splitting results in the states that emit in different colors of the visible region of the electromagnetic spectrum. This work also reveals the discovery both computationally and experimentally, of a genuine polar-covalent bond between two-closed shell metals. This work highlights a complex with an incredibly short gold(I) – copper(I) intermetallic distance leading to a vibrational frequency and dissociation energy that is on par with those of other systems with single-bonded metal centers. Lastly, this work outlines a strategy for the production of hydrogen gas through the use of trinuclear cyclic coinage metal complexes as catalysis to split hydrohalic acids.