PT Unknown
AU Clausen, KU
TI Synthesis, Characterization and Surface Spectroscopic Investigation of Transition-Metal Calix[3]pyridine Complexes
PY 2025
PU Christian-Albrechts-Universität zu Kiel
WP https://macau.uni-kiel.de/receive/macau_mods_00005718
LA en
DE Molybdenum; Carbonyl ligands; O-O-Activation; Analytical Methods
AB This thesis focuses on the surface analytical investigation of transition metal complexes for small molecule activation, with the aim of gaining insight into the interaction between the adsorbed metal center and the underlying metal substrate. To this end, a variety of surface spectroscopy methods have been utilized to study these molecules. The main scope was set to IRRA spectroscopy (infrared reflection absorption spectroscopy). Additionally, STM measurements (scanning tunneling microscopy), XP spectroscopy (X-ray photoelectron spectroscopy) and NEXAFS spectroscopy (near edge X-ray absorption fine structure) were conducted for the characterization of the molecular adlayers. In the first part, this thesis deals with the synthesis and the characterization of a molybdenum(0) tricarbonyl and a molybdenum(VI) trioxo complex supported by an azacalix[3]pyridine ligand in bulk material, in solution and as adsorbates on a gold surface. The subsequent study addresses the rarely described oxidative decarbonylation of a Mo(0) tricarbonyl to its Mo(VI) trioxo analogue. The conversion mechanism with molecular oxygen was investigated in detail in solution and as self-assembled monolayer on an Au(111) surface, employing a range of spectroscopic and analytical methods and were complemented by DFT calculations to propose a reaction mechanism. Furthermore, a molybdenum(0) tricarbonyl complex supported by a thiacalix[3]pyridine ligand was synthesized and characterized as well. In contrast to its azacalix analogue, this complex is more stable towards molecular oxygen as a result of a more regular octahedral geometry. Finally, a custom-built (inert) gas cell for the IRRA spectrometer is presented. This cell has played a vital role to study the synthesized and partially oxygen sensitive molybdenum complex as monolayers on a gold surface.
PI Kiel
ER