Universität zu Köln

Flosbach, Niko Thomas ORCID: 0000-0003-0778-762X (2024). Systematic Studies of Oxoanionic Lanthanoid Salts in their +II and +IV Oxidation States. PhD thesis, Universität zu Köln.

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Abstract

The present work deals with the synthesis of new oxoanionic compounds of the lanthanoids in unusual oxidation states and their chemical and physical characterisation. It was possible to obtain the first structurally characterised oxoanionic compounds of Pr4+ in the form of PrSi3O8 and Pr2Si7O18 by reacting PrO2 and SiO2 in a diamond anvil cell at ca. 29 GPa. The crystal structure of both silicates could be solved by single crystal X-ray diffraction analysis. A unique praseodymium(IV) oxide peroxide with the empirical formula Pr2O5 formed as a product of a competing reaction under the same conditions. The intentional synthesis of this compound was possible by reacting PrO2 and oxygen in a diamond anvil cell at ca. 27 GPa and enabled detailed studies the structure of Pr2O5 which constitutes the most oxygen rich binary phase of any lanthanoid and oxygen. Analogous experiments with PrO2 and P2O5 afforded a new high-pressure modification of PrPO4 which is equivalent to the barite-type structure. A systematic investigation of various solvates of Ln(OTf)2 (Ln = Sm, Eu, Yb) was conducted, in which the physical properties of the compounds were characterised with emphasis on their luminescence. In additional experiments, the applicability of the synthetic methods was examined with respect to different cations and anions. In order to demonstrate the high potential of the triflates in chemical synthesis, the thus far unknown solvent-free azides Ln(N3)2 (Ln = Eu, Yb) were synthesised by salt metathesis and characterised analytically.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Flosbach, Niko Thomas nflosbach@web.de orcid.org/0000-0003-0778-762X UNSPECIFIED
URN:	urn:nbn:de:hbz:38-731919
Date:	March 2024
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Inorganic Chemistry
Subjects:	Chemistry and allied sciences
Uncontrolled Keywords:	Keywords Language Lanthanoids UNSPECIFIED Rare Earths UNSPECIFIED Tetravalent Praseodymium UNSPECIFIED
Date of oral exam:	20 April 2024
Referee:	Name Academic Title Wickleder, Mathias Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/73191