%0 Journal Article %1 Kasack.1995 %A Kasack, Volker %A Kaim, Wolfgang %A Binder, Herbert %A Jordanov, Jeanne %A Roth, Eberhard. %D 1995 %J Inorganic Chemistry %K azodicarbonyl complex complex;electron complex;mixed complex;substituent configuration dinuclear effect electrochem ruthenium valence %N 7 %P 1924--1933 %R 10.1021/ic00111a045 %T When Is an Odd-Electron Dinuclear Complex a Mixed-Valent Species? Tuning of Ligand-to-Metal Spin Shifts in Diruthenium(III,II) Complexes of Noninnocent Bridging Ligands OC(R)NNC(R)O %V 34 %X (Adc-R)Ru(bpy)22n with bpy = 2,2'-bipyridine and adc-R = azodicarbonyl ligands O:C(R)N:NC(R):O, R = NR'2 (piperidyl), OEt, OCH2Ph, Me, Ph, 4-C6H4COOH, and 4-C6H4COOMe, can exist in several oxidn. states (n = 2-, 0, 2+, 3+, 4+) of which the stable (comproportionation const. Kc \textgreater 5 $\times$ 107) and isolable paramagnetic intermediates (n = 3+) exhibit a considerable and remarkably tunable degree of metal/ligand/metal orbital mixing. The occurrence of intense (e \textgreater 7000 M-1 cm-1) and small solvatochromic absorption bands at $\sim$1500 nm, the temp.-dependent magnetic moment (meff = 1.6-2.1 mB) detd. for one deriv., and the IR vibrational spectra did not allow one to make a conclusive detn. of metal oxidn. states; however, the EPR spectra observable only \textless50 K reveal a strongly substituent- (R-) dependent degree of metal contribution to the singly occupied MO. XPS measurements of two 3+ ions which show Ru(II) and Ru(III) signals also exhibit a marked substituent effect on the electronic structure. Whereas the 4+ ions formed at rather pos. potentials also seem to possess strongly mixed frontier orbitals, the stable 2+ ions clearly contain two Ru(II) centers and fully reduced, i.e. 1,2-dicarbonylhydrazido(2-), bridging ligands, O:C(R)-N-N-C(R):O2-. The results are interpreted within a hole vs. electron transfer scheme, based on a three-site MO model for the metal/metal communication in ligand-bridged mixed-valent dimers according to which the intermediates (adc-R)Ru(bpy)223+ are best described as delocalized systems with varying contributions from RuII/(adc-R).bul.-/RuII and RuII/(adc-R)2-/RuIII resonance forms. on SciFinder(R)

@article{Kasack.1995, abstract = {{(Adc-R)[Ru(bpy)2]2}n with bpy = 2,2'-bipyridine and adc-R = azodicarbonyl ligands O:C(R)N:NC(R):O, R = NR'2 (piperidyl), OEt, OCH2Ph, Me, Ph, 4-C6H4COOH, and 4-C6H4COOMe, can exist in several oxidn. states (n = 2-, 0, 2+, 3+, 4+) of which the stable (comproportionation const. Kc {\textgreater} 5 $\times$ 107) and isolable paramagnetic intermediates (n = 3+) exhibit a considerable and remarkably tunable degree of metal/ligand/metal orbital mixing. The occurrence of intense (\textgreek{e} {\textgreater} 7000 M-1 cm-1) and small solvatochromic absorption bands at $\sim$1500 nm, the temp.-dependent magnetic moment (\textgreek{m}eff = 1.6-2.1 \textgreek{m}B) detd. for one deriv., and the IR vibrational spectra did not allow one to make a conclusive detn. of metal oxidn. states; however, the EPR spectra observable only {\textless}50 K reveal a strongly substituent- (R-) dependent degree of metal contribution to the singly occupied MO. XPS measurements of two 3+ ions which show Ru(II) and Ru(III) signals also exhibit a marked substituent effect on the electronic structure. Whereas the 4+ ions formed at rather pos. potentials also seem to possess strongly mixed frontier orbitals, the stable 2+ ions clearly contain two Ru(II) centers and fully reduced, i.e. 1,2-dicarbonylhydrazido(2-), bridging ligands, [O:C(R)-N-N-C(R):O]2-. The results are interpreted within a hole vs. electron transfer scheme, based on a three-site MO model for the metal/metal communication in ligand-bridged mixed-valent dimers according to which the intermediates {(adc-R)[Ru(bpy)2]2}3+ are best described as delocalized systems with varying contributions from RuII/(adc-R).bul.-/RuII and RuII/(adc-R)2-/RuIII resonance forms. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Kasack, Volker and Kaim, Wolfgang and Binder, Herbert and Jordanov, Jeanne and Roth, Eberhard.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/285037b5699fc4d95fb243b6f4e00bb97/huebleriac}, doi = {10.1021/ic00111a045}, interhash = {25714849b0526cc5cc087918a8ef7ff4}, intrahash = {85037b5699fc4d95fb243b6f4e00bb97}, issn = {0020-1669}, journal = {Inorganic Chemistry}, keywords = {azodicarbonyl complex complex;electron complex;mixed complex;substituent configuration dinuclear effect electrochem ruthenium valence}, number = 7, pages = {1924--1933}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {When Is an Odd-Electron Dinuclear Complex a Mixed-Valent Species? Tuning of Ligand-to-Metal Spin Shifts in Diruthenium(III,II) Complexes of Noninnocent Bridging Ligands OC(R)NNC(R)O}, volume = 34, year = 1995 }