Modular synthesis of lanthanide heterobimetallic complexes

Horsewill, Samuel (2021) Modular synthesis of lanthanide heterobimetallic complexes. PhD thesis, University of Glasgow.

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This thesis presents a modular synthesis of lanthanide heterobimetallics incorporating a redox-active bridging ligand, 1,10-phenanthroline-5,6-dione (pd). Monometallic complexes Ln(hfac)3(N,N′-pd) 1-Ln are synthesised and fully characterised, and it is established that Ln(hfac)3 coordinates selectively to the N,N′ coordination site of the ligand. The reaction of 1-Ln with V(Cp)2 results in the two-electron reduction of pd and synthesis of the d-f heterobimetallics Ln(hfac)3(N,N′-O,O′-pd)V(Cp)2 2-Ln.

The pd ligand is reduced using CoCp2 to provide [CoCp2]+[pd]–• 3, the first fully characterised example of the pd radical anion. Reaction of 3 with Ln(hfac)3(THF)2 4-Ln produces the monometallic lanthanide radical compounds [CoCp2]+[Ln(hfac)3(N,N′-pd)]–• 5-Ln, in which Ln(hfac)3 again selectively coordinates to the N,N′ coordination site of the ligand. The photoluminescent properties of the modular system comprising 1-Ln, 4-Ln and 5-Ln are investigated. In this way, the contributions of the different components of the system, including the organic radical, to quenching of lanthanide photoluminescence are identified. Importantly, by using TCSPC to investigate the emission from the ligands, some energy transfer processes from the emissive excited states of the hfac and pd ligands are also observed.

A range of lanthanide reagents are reacted with 3 and 5-Ln to develop a synthesis of lanthanide heterobimetallics. Organolanthanide transmetallation reagents Ln(Cpt)2(OTf)2K 6-Ln and lanthanide scorpionates Ln(Tp)2(OTf) 7-Ln are synthesised and fully characterised for this purpose. Of 6-Ln, 7-Ln and Ln(Tp*)2(OTf), 7-Ln exhibits the best reactivity with 3, selectively coordinating to the O,O′ coordination site of the ligand to produce Ln(Tp)2(O,O′-pd) 8-Ln. Reaction of 8-Ln generated in situ with 4-Ln in toluene solution is shown to successfully produce lanthanide heterobimetallic complexes Ln(hfac)3(N,N′-O,O′-pd)Ln′(Tp)2 9-LnLn′. Ligand redistribution reactions producing side-products such as Ln(Tp)2(hfac) are limited by performing the reaction cold and quenching it as quickly as possible. The solid state molecular structures of 9-YY′ and 9-EuYb are determined and the bond lengths in 9-EuYb are indicative that lanthanide scrambling has not occurred. Photoluminescence spectroscopy of 9-LnLn′ is also consistent with the selective coordination of the lanthanides to the two different binding sites of the ligand.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Colleges/Schools: College of Science and Engineering > School of Chemistry
Supervisor's Name: Farnaby, Dr. Joy
Date of Award: 2021
Depositing User: Theses Team
Unique ID: glathesis:2021-82690
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 08 Feb 2022 11:24
Last Modified: 11 Apr 2022 09:31
Thesis DOI: 10.5525/gla.thesis.82690
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