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Metalloradical Compounds with 1,2-Dipivaloylhydrazido Ligands: Electron Transfer and Alkylation/Protonation Effects
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SYSNO ASEP 0505695 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Metalloradical Compounds with 1,2-Dipivaloylhydrazido Ligands: Electron Transfer and Alkylation/Protonation Effects Author(s) Mondal, S. (DE)
Filippou, V. (DE)
Bubrin, M. (DE)
Schwederski, B. (DE)
Fiedler, Jan (UFCH-W) RID, ORCID
Kaim, W. (DE)Source Title European Journal of Inorganic Chemistry. - : Wiley - ISSN 1434-1948
Roč. 2019, č. 21 (2019), s. 2639-2647Number of pages 9 s. Language eng - English Country DE - Germany Keywords EPR spectroscopy ; Hydrazine ; Ruthenium ; Spectroelectrochemistry ; Spin density Subject RIV CF - Physical ; Theoretical Chemistry OECD category Physical chemistry R&D Projects GA18-09848S GA ČR - Czech Science Foundation (CSF) Method of publishing Limited access Institutional support UFCH-W - RVO:61388955 UT WOS 000471072200012 EID SCOPUS 85065655755 DOI 10.1002/ejic.201900391 Annotation Under oxidative conditions the complexes M(bpy)2Cl2, M = Ru or Os, react with 1,2-dipivaloylhydrazine H2L = tBuC(O)-NH-NH-C(O)-tBu to yield the paramagnetic compounds [M(L)(bpy)2](PF6) {1(PF6), M = Ru and 2(PF6), M = Os}. Crystal structures of 1(ClO4) and 2(PF6) reveal an NNCO chelate coordination of L with d(NN) ≈ 1.39 Å. EPR spectroscopy suggests a metal/ligand mixed situation for the unpaired electron, with 29 % (Ru, 1+) or 46 % (Os, 2+) metal spin contribution according to DFT calculations. Both complex cations exhibit reversible one-electron oxidation and reduction (Kc ≈ 1019 for 1+ and 1012 for 2+) which could also be monitored by IR (νCO) and UV/Vis-NIR spectroelectrochemistry. These data confirm a metal/ligand orbital mixing MII(L·–) ↔ MIII(L2–), with the osmium analogue favoring the latter alternative. Reaction of Ru(bpy)2Cl2 under non-oxidizing conditions yields the intermediate (1H)(PF6) which could be oxidatively deprotonated to 1+ or methylated to (1Me)(PF6), both identified by 1H and 13C NMR. While oxidation of (1H)+ proceeds irreversibly due to proton loss, the reversible spectroelectrochemical oxidation of (1Me)+ suggests a metal-based process RuII(LMe–) → RuIII(LMe–). The results reveal that not only dinuclear complexes of 1,2-diacylhydrazido ligands but also mononuclear analogues are distinguished by remarkably variable metal/ligand mixed contributions to the frontier orbitals. Workplace J. Heyrovsky Institute of Physical Chemistry Contact Michaela Knapová, michaela.knapova@jh-inst.cas.cz, Tel.: 266 053 196 Year of Publishing 2020 Electronic address http://hdl.handle.net/11104/0297107
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