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 compds. 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) $\approx$ 1.39 \AA. 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 calcns. Both complex cations exhibit reversible one-electron oxidn. and redn. (Kc $\approx$ 1019 for 1+ and 1012 for 2+) which could also be monitored by IR (nCO) and UV/Vis-NIR spectroelectrochem. These data confirm a metal/ligand orbital mixing MII(L·-) $łeftrightarrow$ MIII(L2-), with the osmium analog 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 oxidn. of (1H)+ proceeds irreversibly due to proton loss, the reversible spectroelectrochem. oxidn. of (1Me)+ suggests a metal-based process RuII(LMe-) $\rightarrow$ RuIII(LMe-). The results reveal that not only dinuclear complexes of 1,2-diacylhydrazido ligands but also mononuclear analogs are distinguished by remarkably variable metal/ligand mixed contributions to the frontier orbitals. on SciFinder(R)
%0 Journal Article
%1 Mondal.2019
%A Mondal, Sudipta
%A Filippou, Vasileios
%A Bubrin, Martina
%A Schwederski, Brigitte
%A Fiedler, Jan
%A Kaim, Wolfgang.
%D 2019
%J European Journal of Inorganic Chemistry
%K alkylation calcn complex complex;spectroelectrochem crystal dipivaloylhydrazido effect mol osmium prepn protonation ruthenium structure structure;electron transfer
%N 21
%P 2639--2647
%R 10.1002/ejic.201900391
%T Metalloradical Compounds with 1,2-Dipivaloylhydrazido Ligands: Electron Transfer and Alkylation/Protonation Effects
%V 2019
%X 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 compds. 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) $\approx$ 1.39 \AA. 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 calcns. Both complex cations exhibit reversible one-electron oxidn. and redn. (Kc $\approx$ 1019 for 1+ and 1012 for 2+) which could also be monitored by IR (nCO) and UV/Vis-NIR spectroelectrochem. These data confirm a metal/ligand orbital mixing MII(L·-) $łeftrightarrow$ MIII(L2-), with the osmium analog 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 oxidn. of (1H)+ proceeds irreversibly due to proton loss, the reversible spectroelectrochem. oxidn. of (1Me)+ suggests a metal-based process RuII(LMe-) $\rightarrow$ RuIII(LMe-). The results reveal that not only dinuclear complexes of 1,2-diacylhydrazido ligands but also mononuclear analogs are distinguished by remarkably variable metal/ligand mixed contributions to the frontier orbitals. on SciFinder(R)
@article{Mondal.2019,
abstract = {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 compds. [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) $\approx$ 1.39 {\AA}. 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 calcns. Both complex cations exhibit reversible one-electron oxidn. and redn. (Kc $\approx$ 1019 for 1+ and 1012 for 2+) which could also be monitored by IR (\textgreek{n}CO) and UV/Vis-NIR spectroelectrochem. These data confirm a metal/ligand orbital mixing MII(L·-) $\leftrightarrow$ MIII(L2-), with the osmium analog 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 oxidn. of (1H)+ proceeds irreversibly due to proton loss, the reversible spectroelectrochem. oxidn. of (1Me)+ suggests a metal-based process RuII(LMe-) $\rightarrow$ RuIII(LMe-). The results reveal that not only dinuclear complexes of 1,2-diacylhydrazido ligands but also mononuclear analogs are distinguished by remarkably variable metal/ligand mixed contributions to the frontier orbitals. [on SciFinder(R)]},
added-at = {2019-07-15T13:41:23.000+0200},
author = {Mondal, Sudipta and Filippou, Vasileios and Bubrin, Martina and Schwederski, Brigitte and Fiedler, Jan and Kaim, Wolfgang.},
biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2749b81ca5cbb600a1eaf5a100b0e9d5f/b_schwederski},
doi = {10.1002/ejic.201900391},
interhash = {9408374c2f25345678ce79d71fdf8514},
intrahash = {749b81ca5cbb600a1eaf5a100b0e9d5f},
issn = {1434-1948},
journal = {European Journal of Inorganic Chemistry},
keywords = {alkylation calcn complex complex;spectroelectrochem crystal dipivaloylhydrazido effect mol osmium prepn protonation ruthenium structure structure;electron transfer},
number = 21,
pages = {2639--2647},
timestamp = {2019-07-15T11:42:10.000+0200},
title = {Metalloradical Compounds with 1,2-Dipivaloylhydrazido Ligands: Electron Transfer and Alkylation/Protonation Effects},
volume = 2019,
year = 2019
}
