1. Lanthanide organometallic complexes : synthesis and applications in single-molecule magnetism
- Author
-
Collins, Richard and Collison, David
- Subjects
pentalene ,carbonyl ,organometallic ,single molecule magnet ,magnet ,lanthanide ,magnetism - Abstract
Single-molecule magnets (SMMs) are a classification of molecular nanomagnets which can display slow relaxation of magnetisation. This is manifested in magnetic properties that are not reliant upon the cooperative interactions across domains of spins. This thesis aims to synthesise and characterise lanthanide organometallic complexes and to investigate the resultant magnetic properties. 4f/3d isocarbonyl complexes have previously been shown to display single-molecule magnet behaviour with large energy barriers to reversal of magnetisation, as a result of cooperative effects between the two individual metal centres facilitated by the isocarbonyl link. Isocarbonyl bridging ligands present an opportunity to explore the structural and electronic effects of bridging systems in relation to SMMs, as polymetallic complexes may provide higher blocking temperatures and energy barriers. Here, research is focused on utilising the heavier d-block metal tungsten, in combination with 4f elements to investigate the effect on both the structural and magnetic properties in order to expand on the understanding of isocarbonyl SMMs. The development of easily handled lanthanide organometallic building blocks, based around the 10π-aromatic-8-membered cyclooctatetraene dianion ([COT]²⁻), for future SMM design are also synthesised and their solid-state properties characterised. Though K₂COT and some COT ligated species can be extremely air sensitive and pyrophoric, the materials reported in this thesis showed no pyrophoricity and a reduced, but not dispelled, air sensitivity relative to previously reported work. The separated-ion pairs are subjected to investigations of their magnetic properties, which is informative for future efforts to synthesise [COT]²⁻-based SMMs. The second example of lanthanide inverse-sandwich pentalene complexes are synthesised and their solid-state structures are investigated, alongside computational analysis that demonstrates the change in direction of the principle magnetic axis. The precursor complexes are also characterised structurally and magnetically, to afford further insight into the effects of the ligands upon magnetic properties.
- Published
- 2021