Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 15: Postersitzung (Adsorption an Oberfl
ächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Rastersondentechniken, Zeitaufgelöste Spektroskopie, Methoden)
O 15.44: Poster
Freitag, 4. März 2005, 17:00–20:00, Poster TU D
NMR and XAFS Investigation of the Structure of Mo(allyl)4 Followed by Wet Chemical Deposition of the Complex on a Thin Al2O3 Film and Subsequent Characterisation Using XPS — •Karifala Dumbuya1, Sven Schroeder2, Norbert Weiher2, Klaus Christmann1, and Tal Perry1 — 1Free University Berlin, Institute of Chemistry, Department of Physical and Theoretical Chemistry, Takustrasse 3, 14195 Berlin — 2University of Manchester, School of Chemical Engineering and School of Chemistry, PO Box 88 Sackville Street, Manchester M 60 1 QD, UK
We report the synthesis and structural ellucidation of Mo(C3H5)4 using solid and liquid state NMR (13C, 1H) and XAFS of the complex in solution. The NMR results agree remarkably well with previous work with the 1H showing five resonances (four doublets and a multiplet) indicating five different protons. The 13C also revealed three different carbons, suggesting that all four allyl groups are equivalent. To our knowledge, this is the first attempt at soild state NMR study on this complex. XAFS investigation of the Mo k-edge revealed a cordination number of 3.6 for molybdenum in the first cordination shell, i.e., an average of 11 C-atoms. The average Mo-C distance was 2.35 Å, a value which compares well with Mo-C distances in related molybdenum complexes and supports the case for a symmetrical pi-allyl system. Depostion of the complex from a solution of pentane on a freshly prepared Al2O3 surface in ultra high Vacuum with the help of a specially designed transfer cell proved very successful, albeit significant silicon contamination. Investigation of the contaminant is in progress.