Assignment of pre-edge features in the Ru K-edge X-ray absorption spectra of organometallic ruthenium complexes |
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Authors: | Kendra Getty |
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Institution: | Department of Chemistry, The University of British Columbia, Vancouver BC, Canada V6T 1Z1 |
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Abstract: | The nature of the lowest energy bound-state transition in the Ru K-edge X-ray absorption spectra for a series of Grubbs-type ruthenium complexes was investigated. The pre-edge feature was unambiguously assigned as resulting from formally electric dipole forbidden Ru 4d ← 1s transitions. The intensities of these transitions are extremely sensitive to the ligand environment and the symmetry of the metal centre. In centrosymmetric complexes the pre-edge is very weak since it is limited by the weak electric quadrupole intensity mechanism. By contrast, upon breaking centrosymmetry, Ru 5p-4d mixing allows for introduction of electric dipole allowed character resulting in a dramatic increase in the pre-edge intensity. The information content of this approach is explored as it relates to complexes of importance in olefin metathesis and its relevance as a tool for the study of reactive intermediates. |
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Keywords: | Ruthenium complexes X-ray absorption spectroscopy Olefin metathesis Assignment of pre-edge features Electronic and geometric structure |
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