Synthesis, Characterisation and Analysis of Ruthenium Pincer Complexes with Strongly 𝜋-acidic Ligands

In this thesis, the results of five sub-projects from the PhD project are presented and discussed. Of these results, the synthesis and characterisation of a series of related carbonyl hydrido complexes of Ru^II will be presented first. Each of these complexes has been spectroscopically and structurally characterised. The crystallographic models was refined by means of both the Independent Atom Model (IAM) and the Hirschfeld Atom Refinement (HAR) method. The models represented by each of the refinement methods were compared together as well as compared to the spectroscopic characteristics of each compound in order to gain potential correlations of the spectroscopic observables and the Ru-H bond distance.
Synthesis, characterisation and reactivity studies of a series of ruthenium nitrosyl complexes make up for a substantial volume of this thesis. During these investigations, a series of unprecedented zero-valent five-coordinate Ru-halido complexes were unearthed. The new Ru-halide species were accessed by computational methods as well as single-crystal X-ray diffraction and spectroscopic characterisation. Additionally, some of the new itrosyl species have been screened for catalytic activity in transfer hydrogenation of organic carbonyl derivatives and a selection of results will be presented in this thesis.
The complex commercially distributed as "Ru-MACHO" is known as a highly active catalyst in a variety of hydrogenation reactions, and is utilised in both industry and academia. Despite the high scientific values of this compound, no irrefutable proof of the proposed structure has, so far, been communicated. However, during the PhD studies that are represented by this thesis, a high quality crystal structure of the Ru-MACHO compound was obtained. Additionally, the reaction product for the reaction between Ru-MACHO and chloroform was elucidated by means of single-crystal X-ray diffraction. These results points at a general protocol for the synthesis of chlorido species via chloride-hydride exchange.
The thesis is divided into seven chapters. The first chapter gives the reader a general introduction to the fields of pincer, carbonyl and nitrosyl chemistry. Then follows five chapters dedicated to a presentation and discussion of the main results obtained in the five projects (one per chapter). The sixth chapter is written as a draft for a journal paper. The seventh chapter serves as a general conclusion and future perspectives of the works presented throughout this thesis.