Z. Naturforsch. 2014, 69b, 1164 – 1180
Thiocyanate Anchors for Salt-like Iron(II) Complexes on Au(111): Promises and Caveats
Philipp Stock1,2, Andreas Erbe2, Manfred Buck3, Dennis Wiedemann1, Hervé Ménard4, Gerald Hörner1, and Andreas Grohmann1
1 Institut für Chemie, Sekr. C2, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
2 Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
3 EaStCHEM School of Chemistry, University of St Andrews, St Andrews KY16 9ST, United Kingdom
4 Sasol Technology (UK) Ltd, Purdie Building, North Haugh, St Andrews, KY16 9ST, United Kingdom
Reprint requests to Professor Andreas Grohmann. Fax: +49-30 31479656. E-mail: andreas.grohmann@tu-berlin.de
Received July 15, 2014 / published online December 19, 2014
Dedicated to Professor Hubert Schmidbaur on the occasion of his 80th birthday
The formation of self-assembled monolayers (SAMs) on Au(111) from solution has been investigated for two ionic iron(II) complexes of the type [Fe(L)](BF4)2, where L is tripodal hexadentate and contains three thiocyanate anchor groups. The ligands (L1, L2; donor set: N6) are obtained by Schiff base condensation of a tripodal triamine (L1: tris-(2-aminoethyl)amine, ‘tren’; L2: 1,1′,1′′-trimethyl(thiophosphoryl)trihydrazide) with 5-(4-thiocyanatobutoxy) pyridine-2-carbaldehyde. Layers of the complexes adsorbed on Au(111) from methanol solution have been characterised using scanning tunnelling microscopy (STM), infrared reflectance absorbance (IRRAS), X-ray photoelectron (XPS) and UV/Vis reflectance spectroscopies, as well as ellipsometry. Complex [Fe(L1)](BF4)2 deposits intact on a gold surface and retains its optical addressability. Elaboration of this result may provide access to a new class of self-assembled layers, employing salt-like tripodal coordination compounds with thiocyanate anchors. The second complex, [Fe(L2)](BF4)2, which contains a sulphur atom in the ligand backbone, is not sufficiently stable under the same conditions.
Key words: Responsive Surfaces, Au(111), Iron(II), Nitrogen Ligands, Magnetic Properties
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