AbstractCoordination chemistry of the transition metals is a key topic in current inorganic chemistry, due to the extensive use of metallic complexes in chemistry, specially as catalysts. In this thesis a computational approach to their chemistry is done, with the use of several computational techniques applied to the study of several chemical aspects.
The first part of this thesis is devoted to the structural study of a series of Pd(II) T-shaped complexes. Such electron-deficient complexes (formally 14-electron species) have caused a great controversy and for this reason the effect of the ligands in their stability was systematically studied by DFT methods. Pd(II)-amide bond, a metal-ligand interaction leading to a characteristic T-shaped stabilization was studied further with the extension of the systematic study to its substituents and the performance of different electron density analysis on the metal-ligand bond.
The second part of this thesis is formed by reactivity studies in the activation of inert C-H bonds, a key issue in synthesis. Mechanisms of different C-H bond activation reactions were found for the activation by metallic complexes of gold(III) and iridium(III) of simple organic molecules containing both alkylic and arylic C-H bonds. With a [IrTpMe2] moiety, anisole is activated in three different positions, forming an aryl-carbene ligand. AuCl3 catalyzed insertion of a nitrene into C-H bonds of alkylarenes, lead to the competitive activation of benzylic and arylic positions depending on the substrate. Mechanisms for these reactions are proposed computationally.
In the third part of this thesis, the computation of NMR parameters has been considered. A method for the computation of the NMR spin-spin coupling (J-coupling) has been tested for a wide benchmark of experimentally computed couplings. This method has been evaluated with different functionals (PBE and the hybrid PBE0) and with one- and two-component relativistic approaches. In addition, the observed trends in the nuclear shielding of a series of lanthanum halides were analyzed by decomposition of the computed parameter.
The use of computational methods to study several aspects of transition metal complexes (structure, reactivity and NMR properties) is shown to be a highly useful tool.
|Date of Award||16 Jul 2010|
|Supervisor||Agusti Lledos Falco (Director) & Gregori Ujaque Perez (Director)|