%0 Journal Article %1 Ansari.2020 %A Ansari, Mohd. Asif %A Mondal, Sudipta %A Kaim, Wolfgang %A Lahiri, Goutam Kumar. %D 2020 %J Inorganic Chemistry %K acetylacetonate complex complex;cyclic complex;prepn crystal diruthenium mol pyridil structure voltammetry %N 7 %P 4397--4405 %R 10.1021/acs.inorgchem.9b03543 %T Fused N-Heterocyclic-Bridged Isomeric Diruthenium Complexes [(acac)2Ru(m-DIPQD)Ru(acac)2]n, n = +2, + 1, 0, -1, -2 %V 59 %X p-Conjugated bridged isomeric diruthenium(II) complexes [(acac)2RuII(m-DIPQD)RuII(acac)2], 1 (trans) and 2 (cis) (acac- = acetylacetonate), (8E,16E)-N8,N16-diphenylindeno[1,2-b]indeno[2',1':5,6]pyrazino[2,3-g]quinoxaline-8,16-diimine (trans-DIPQD), and (12E,16E)-N12,N16-diphenylindeno[1,2-b]indeno[1',2':5,6]pyrazino[2,3-g]quinoxaline-12,16-diimine (cis-DIPQD) were sepd. and structurally characterized. The structures of the rac (DD/LL) forms of 1 and 2 exhibit two units of Ru(acac)2, linked to adjacent pyrazine and imine nitrogen donors of the bridge (DIPQD) in trans and cis modes, with metal-metal sepns. of 9.050 and 6.330 \AA, resp. The packing diagrams of 1 and 2 revealed an intermol. p···p stacking interaction (3.202-3.398 \AA) involving the face-to-face arrangement of the arom. rings of DIPQD in adjacent mols. and varying solid-state packing modes, slipped stacking in the former vs. brick-layer stacking in the latter. The electronic forms assocd. with multiple reversible one-electron redox steps of 1 and 2 were addressed by DFT (MO compn., Mulliken spin d. distribution), supported by EPR of intermediate paramagnetic states and by UV-visible-NIR spectroelectrochem. in all redox states. The results reveal similar electronic forms along the redox series irresp. of their isomeric identities in 1 and 2, viz., primarily metal-based oxidns. ([(acac)2RuII(m-DIPQD)RuIII(acac)2]+, 1+/2+, S = 1/2; [(acac)2RuIII(m-DIPQD)RuIII(acac)2]2+, 12+/22+, S = 1) and bridge-based redns. ([(acac)2RuII(m-DIPQD.bul.-)RuII(acac)2]-, 1.bul.-/2.bul.-, S = 1/2; [(acac)2RuII(m-DIPQD2-)RuII(acac)2]2-, 12-/22-, S = 1). TD-DFT anal. of the electronic transitions in the complexes suggests bridge-targeted mixed metal/ligand-based multiple charge transfer transitions over the visible to NIR region in all redox states, while a weak band involving the radical bridge appeared in the long-wavelength region ($\sim$2000 nm) in 1.bul.-/2.bul.-. Isomeric diruthenium complexes (trans-1 and cis-2) involve an extended conjugated bridging p-system, including seven fused rings and two terminal phenylimine functions exhibiting varying modes of intermol. p···p stacking interactions, and different redox potentials and electronic configurations along the redox states. DFT calcns. revealed an asym. distribution of the (localized) unpaired spin in 2+, in agreement with class ii mixed-valent behavior, and a more localized spin distribution in 1+. [on SciFinder(R)]

@article{Ansari.2020, abstract = {\textgreek{p}-Conjugated bridged isomeric diruthenium(II) complexes [(acac)2RuII(\textgreek{m}-DIPQD)RuII(acac)2], 1 (trans) and 2 (cis) (acac- = acetylacetonate), (8E,16E)-N8,N16-diphenylindeno[1,2-b]indeno[2',1':5,6]pyrazino[2,3-g]quinoxaline-8,16-diimine (trans-DIPQD), and (12E,16E)-N12,N16-diphenylindeno[1,2-b]indeno[1',2':5,6]pyrazino[2,3-g]quinoxaline-12,16-diimine (cis-DIPQD) were sepd. and structurally characterized. The structures of the rac (\textgreek{DD}/\textgreek{LL}) forms of 1 and 2 exhibit two units of {Ru(acac)2}, linked to adjacent pyrazine and imine nitrogen donors of the bridge (DIPQD) in trans and cis modes, with metal-metal sepns. of 9.050 and 6.330 {\AA}, resp. The packing diagrams of 1 and 2 revealed an intermol. \textgreek{p}···\textgreek{p} stacking interaction (3.202-3.398 {\AA}) involving the face-to-face arrangement of the arom. rings of DIPQD in adjacent mols. and varying solid-state packing modes, slipped stacking in the former vs. brick-layer stacking in the latter. The electronic forms assocd. with multiple reversible one-electron redox steps of 1 and 2 were addressed by DFT (MO compn., Mulliken spin d. distribution), supported by EPR of intermediate paramagnetic states and by UV-visible-NIR spectroelectrochem. in all redox states. The results reveal similar electronic forms along the redox series irresp. of their isomeric identities in 1 and 2, viz., primarily metal-based oxidns. ([(acac)2RuII(\textgreek{m}-DIPQD)RuIII(acac)2]+, 1+/2+, S = 1/2; [(acac)2RuIII(\textgreek{m}-DIPQD)RuIII(acac)2]2+, 12+/22+, S = 1) and bridge-based redns. ([(acac)2RuII(\textgreek{m}-DIPQD.bul.-)RuII(acac)2]-, 1.bul.-/2.bul.-, S = 1/2; [(acac)2RuII(\textgreek{m}-DIPQD2-)RuII(acac)2]2-, 12-/22-, S = 1). TD-DFT anal. of the electronic transitions in the complexes suggests bridge-targeted mixed metal/ligand-based multiple charge transfer transitions over the visible to NIR region in all redox states, while a weak band involving the radical bridge appeared in the long-wavelength region ($\sim$2000 nm) in 1.bul.-/2.bul.-. Isomeric diruthenium complexes (trans-1 and cis-2) involve an extended conjugated bridging \textgreek{p}-system, including seven fused rings and two terminal phenylimine functions exhibiting varying modes of intermol. \textgreek{p}···\textgreek{p} stacking interactions, and different redox potentials and electronic configurations along the redox states. DFT calcns. revealed an asym. distribution of the (localized) unpaired spin in 2+, in agreement with class ii mixed-valent behavior, and a more localized spin distribution in 1+. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Ansari, Mohd. Asif and Mondal, Sudipta and Kaim, Wolfgang and Lahiri, Goutam Kumar.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2dd4215768db1f143428274eb9d7978ee/huebleriac}, doi = {10.1021/acs.inorgchem.9b03543}, interhash = {60a68940c6fba6d1f4ee60d02f562098}, intrahash = {dd4215768db1f143428274eb9d7978ee}, issn = {0020-1669}, journal = {Inorganic Chemistry}, keywords = {acetylacetonate complex complex;cyclic complex;prepn crystal diruthenium mol pyridil structure voltammetry}, number = 7, pages = {4397--4405}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Fused N-Heterocyclic-Bridged Isomeric Diruthenium Complexes [(acac)2Ru(\textgreek{m}-DIPQD)Ru(acac)2]n, n = +2, + 1, 0, -1, -2}, volume = 59, year = 2020 }