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Resonant X-ray photo-oxidation of light-harvesting iron (II/III) N-heterocyclic carbene complexes

Two photoactive iron N-heterocyclic carbene complexes [Formula: see text] and [Formula: see text] , where btz is 3,3’-dimethyl-1,1’-bis(p-tolyl)-4,4’-bis(1,2,3-triazol-5-ylidene) and bpy is 2,2’-bipyridine, have been investigated by Resonant Photoelectron Spectroscopy (RPES). Tuning the incident X-r...

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Detalles Bibliográficos
Autores principales: Temperton, Robert H., Guo, Meiyuan, D’Acunto, Giulio, Johansson, Niclas, Rosemann, Nils W., Prakash, Om, Wärnmark, Kenneth, Schnadt, Joachim, Uhlig, Jens, Persson, Petter
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8590020/
https://www.ncbi.nlm.nih.gov/pubmed/34772983
http://dx.doi.org/10.1038/s41598-021-01509-7
Descripción
Sumario:Two photoactive iron N-heterocyclic carbene complexes [Formula: see text] and [Formula: see text] , where btz is 3,3’-dimethyl-1,1’-bis(p-tolyl)-4,4’-bis(1,2,3-triazol-5-ylidene) and bpy is 2,2’-bipyridine, have been investigated by Resonant Photoelectron Spectroscopy (RPES). Tuning the incident X-ray photon energy to match core-valence excitations provides a site specific probe of the electronic structure properties and ligand-field interactions, as well as information about the resonantly photo-oxidised final states. Comparing measurements of the Fe centre and the surrounding ligands demonstrate strong mixing of the Fe [Formula: see text] levels with occupied ligand [Formula: see text] orbitals but weak mixing with the corresponding unoccupied ligand orbitals. This highlights the importance of [Formula: see text] -accepting and -donating considerations in ligand design strategies for photofunctional iron carbene complexes. Spin-propensity is also observed as a final-state effect in the RPES measurements of the open-shell [Formula: see text] complex. Vibronic coupling is evident in both complexes, where the energy dispersion hints at a vibrationally hot final state. The results demonstrate the significant impact of the iron oxidation state on the frontier electronic structure and highlights the differences between the emerging class of [Formula: see text] photosensitizers from those of more traditional [Formula: see text] complexes.