Molecular Orbitals of Transition Metal Complexes

Lectures
The theoretical module (6 ECTS, 48 hours) provides the conceptual tools required to understand and predict the structure and behaviour of coordination compounds and organometallic species. The course is divided into four key areas:
Orbital Interaction and Symmetry: After illustrating the principles of orbital interaction, practical examples show how to use group theory to construct molecular orbital diagrams for the main families of ligands, and the consequences of the presence of d-electrons in the valence shell of transition metals on their bonding capabilities are discussed.
Sigma Interactions: The electronic structure for the most common coordination geometries, both of stable species and unsaturated molecular fragments, is derived and discussed using an approach based on symmetry, orbital interaction, and geometric perturbation.
Pi Interactions: Perturbations of the sigma framework resulting from the introduction of pi-donor and pi-acceptor ligands into the coordination sphere are analysed. Pi-complexes are then described through the Dewar-Chatt-Duncanson model, and linear and bent metallocenes are examined, with particular emphasis on their bonding properties.
Applications: The effectiveness of the described methods will be demonstrated through a series of applications. As a purely illustrative example, exam topics will be selected from a pool of subjects including: conformational problems, sigma complexes (molecular hydrogen complexes and agostic species), multiple metal-ligand and metal-metal bonding, reactivity (reductive elimination, cyclometallation), structure and properties of metal clusters. The principles of the isolobal analogy and the connections relating inorganic, organometallic, and organic species will also be illustrated. The actual list of case studies may be integrated or modified based on proposals from the students.
Computational Laboratory
The laboratory (3 ECTS, 48 hours) offers an application-based experience where modern computational chemistry methods are employed to analyse and solve real-world case studies. The practical path is divided into the following activities:
Exercises Supporting the Lectures: Use of semi-empirical calculations of the Extended Hückel type to describe orbital interactions for some of the systems examined during lectures.
Introduction to Density Functional Theory (DFT) methods: Calculation of the electronic structure and geometry optimization of simple organometallic complexes. Modelling of the Berry pseudorotation process.
Analysis of Electronic Effects: Quantification of the donating properties of phosphines and phosphites. Prediction of regioselectivity for the nucleophilic attack reaction on complexes of substituted arenes and heterocycles.
Chemical Bonding and Reactivity: Investigation into the nature of multiple bonds involving both main group elements and transition metals. Prediction of the nucleophilic, electrophilic, and amphiphilic character of carbenic carbon. Thermodynamic and kinetic modelling of the migratory insertion reaction.
Photophysical properties: Characterization of electronic absorption transitions, geometry and nature of the first triplet state, as well as the transition responsible for phosphorescence in a luminescent organometallic species.