Novel reactivity of low oxidation state main group compounds

Main group chemistry has seen significant advances over the past few decades. A plethora of highly unusual molecular main group compounds has been reported in recent years that challenge our understanding of chemical bonding and element-element interactions. Many of these molecules (or mixtures) have been found to contain a combination of unusual bonding modes and a high energy electronic configuration that is often combined with vacant orbitals and empty coordination sites. Many species furthermore show relatively small HOMO-LUMO gaps and/or even possess a small singlet-triplet energy gap. As a consequence, these types of molecules show a unique reactivity and some are capable of activating relatively inert molecules. This novel reactivity can be developed into new reactions and even catalytic protocols. Many of these novel main group element species are low oxidation state compounds. Their reactivity is directly related to the high energy electronic state and the frontier orbital configuration of the low oxidation state element. To access highly novel low oxidation state main group compound, suitable ligand systems need to be developed and employed in the stabilization of those species. Both the electronic and steric requirements are highly important, and often subtle changes of the ligand system can lead to very different outcomes. This projects will explore the synthesis and characterization of novel low oxidation state compounds of group 2, 13 and 14 elements and study the properties and reactivity of these species. To this end, we will use, design and develop a range of sterically demanding ligands and study their ability to stabilize novel low oxidation state main group compounds. Based on previously used compound classes within our group, a range of iminophosphorane, phosphinoamide, Bdiketiminate and other neutral and anionic donor ligands will be employed. Often, suitable ligand precursors are reacted with main group element starting materials to form typically heteroleptic element compounds and the reduction chemistry of those species can be investigated. The chemistry of the resulting novel low oxidation state compounds will be studied for unusual activation reactions towards a range of (small) molecules including industrially relevant compounds. We target the unusual and novel activation of - and -bonds and will develop these into new reactions and possibly novel catalytic transformations. Reaction monitoring will be predominantly carried out by multinuclear NMR spectroscopy, compound characterization of isolated compounds will be achieved by a combination of analytical techniques including multinuclear NMR spectroscopy, X-ray crystallography, IR spectroscopy, elemental analysis, mass spectrometry and other suitable methods. To this end, the School of Chemistry at the University of St Andrews runs a series of state-of-the-art analytical and spectroscopic laboratories and services, and houses internationally leading research groups with a wide expertise in the chemical sciences.

The student will learn various techniques regarding the synthesis, isolation and characterization of air and moisture sensitive and possibly thermally unstable molecular main group complexes, as well as those of specialized organic ligand systems and some inorganic solids. Handling techniques will include Schlenk line and glove box techniques under dry inert gas in combination with specialized glassware and modern laboratory equipment. The student will further deepen his knowledge and skills for the preparation of samples including some hands-on training for acquiring spectral data for some analytical techniques (e.g. NMR spectroscopy, IR spectroscopy) and how to prepare and submit samples for other analytical tools. In addition, safe working in a laboratory environment, laboratory organization, research planning, knowledge of relevant literature, presentation, reporting and writing skills and other expertise will be improved upon.