Metalloradical Compounds with 1,2-Dipivaloylhydrazido Ligands: Electron Transfer and Alkylation/Protonation Effects
Result description
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.
Keywords
EPR spectroscopyHydrazineRutheniumSpectroelectrochemistrySpin density
The result's identifiers
Result code in IS VaVaI
Result on the web
DOI - Digital Object Identifier
Alternative languages
Result language
angličtina
Original language name
Metalloradical Compounds with 1,2-Dipivaloylhydrazido Ligands: Electron Transfer and Alkylation/Protonation Effects
Original language description
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.
Czech name
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Czech description
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Classification
Type
Jimp - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
10403 - Physical chemistry
Result continuities
Project
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2019
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
European Journal of Inorganic Chemistry
ISSN
1434-1948
e-ISSN
—
Volume of the periodical
2019
Issue of the periodical within the volume
21
Country of publishing house
DE - GERMANY
Number of pages
9
Pages from-to
2639-2647
UT code for WoS article
000471072200012
EID of the result in the Scopus database
2-s2.0-85065655755
Basic information
Result type
Jimp - Article in a specialist periodical, which is included in the Web of Science database
OECD FORD
Physical chemistry
Year of implementation
2019