| dc.description.abstract | Over the past two decades, the chemistry of binuclear complexes containing a transition metal and a main group element from the 4th and 5th period has attracted a renewed interest prompted by the atypical transition metal-main group element interaction present at the core of these complexes. Special attention has been devoted to cases where the main group element behaves as a Lewis acid and the metal (M) as a Lewis base. According to the Covalent Bond Classification method, the main group element in these complexes acts as a Z-type ligand and draws density from the metal atom via a direct M→Z interaction. In addition to that being of fundamental interest, the presence of this interaction provides a vector for controlling the electron density of the metal atom, offering new opportunities in metal mediated catalysis. The presence of this interaction may also manifest in the atypical redox properties that these complexes sometimes display. Examples of such behavior include the susceptibility of some of these complexes to undergo light-driven reduction processes.
With the view of understanding the factors that control the strength of M→Z interactions, the first objective of this dissertation has been to computationally survey a series of model complexes containing Pt(0) as a metallobase and the Lewis acidic main group fluorides of group 13, 14, and 15. Using CO, CH₃CN, and CH₃NC as probe molecules, we have been able to confirm that Lewis acidity increases down a group. These studies also reveal the existence of an island of high Lewis acidity, including In(III), Ge(IV), Sn(IV), As(V), and Sb(V) fluorides. Drawing on the conclusion of this computational survey, it became the second objective of this dissertation to investigate the synthesis of complexes containing platinum as a metallobase and a germanium (IV) moiety as a Z-type ligand. These efforts have resulted in the characterization of a complex in which a Pt(II) center is held by two ancillary phosphine ligands in proximity to the Ge(IV) center. The structure, spectroscopic, and computed properties of this complex have confirmed the existence of a Pt(II)→Ge(IV) interaction. Owing to the presence of this interaction, the complex can be photoreduced cleanly in the presence of a sacrificial reducing agent to afford the corresponding Pt(I)-Ge(III) as a result of chlorine elimination. With the view to test the generality of these findings, the third objective of this dissertation has been to investigate the synthesis of related Pd-Ge complexes. In this case, we observed that the reductive process described above for platinum takes place thermally, without the need for UV irradiation, leading to the corresponding Pd(I)-Ge(III) complex. Finally, this dissertation also explores some aspects of the chemistry of bimetallic gold (I) and gold(II) complexes as carbophilic catalysts. The main conclusion from this study is that a positive correlation exists between the catalytic activity of these complexes and the oxidation state of the gold center. | en |
