Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 73: Surface Dynamics: Reactions and Elementary Processes
O 73.7: Poster
Mittwoch, 9. März 2016, 18:15–20:30, Poster A
A transition metal complex transformation in ionic liquids monitored by photoelectron spectroscopy — •Benjamin May, Michael Hönle, Hans-Peter Steinrück, and Florian Maier — Chair Physical Chemistry II, FAU University Erlangen-Nürnberg, Germany
Ionic liquids (ILs) — salt melts with melting points below 373 K do exhibit an extremely low vapor pressure making them suitable for surface science investigations under ultra-high vacuum conditions, in contrast to conventional molecular liquids. Within the last years, our group performed various types of fundamental reaction studies in ILs in combination with X-ray photoelectron spectroscopy (XPS).[1] Here, we report on a temperature-dependent IL metal complex transformation.
The transition metal IL [EMIM]2[Co(NCS)4][2] was mixed with the IL [EMIM][NCS]. Osborne et. al. reported thermochromic behavior for a similar system: in the presence of an excess of free thiocyanate anions, the blue tetrahedral [Co(NCS)4]2− complex anion reversibly forms below 223 K a pink octahedral [Co(NCS)6]4− complex.[3]
In our study, IL signals were monitored by XPS and UPS between room temperature and 213 K. Below the transition temperature, changes in the Co2p line were observed indicating a shift of the complex equilibrium towards the octahedral complex.
[1] H.-P. Steinrück, Phys. Chem. Chem. Phys. 2012, 14, 5010-5029.
[2] T. Peppel, et. al., Angew. Chem. Int. Ed. 2010, 49, 7116-7119.
[3] S.J. Osborne, et. al. , Dalton Trans. 2015, 44, 11286-11289.