%0 Journal Article %1 Das.2012 %A Das, Amit %A Scherer, Thomas Michael %A Chowdhury, Abhishek Dutta %A Mobin, Shaikh M. %A Kaim, Wolfgang %A Lahiri, Goutam Kumar. %D 2012 %J Inorganic Chemistry %K asym azobis calcn cationic complex complex;mol cymene mol prepn pyridine ruthenium structure structure;crystal %N 3 %P 1675--1684 %R 10.1021/ic201975h %T Asymmetrical Diruthenium Complex Bridged by a Redox-Active Ligand %V 51 %X The asym. dinuclear complex (acac)2Ru1(m-abpy)Ru2(Cym)ClPF6 (2PF6), with acac- = acetylacetonato = 2,4-pentanedionato, abpy = 2,2'-azobis(pyridine), and Cym = p-cymene = 1-isopropyl-4-methylbenzene, has been obtained from the mononuclear precursors Ru(acac)2(abpy) and Ru(Cym)Cl22. X-ray crystal structure anal. suggests the oxidn. state formulation (acac)2Ru1III(m-abpy·-)Ru2II(Cym)Cl+ for 2+, with antiferromagnetic coupling between one RuIII center and the radical-anion bridging ligand (abpy·-), based on the N-N distance of 1.352(3) \AA. As appropriate refs., the newly synthesized mononuclear (abpy)RuII(Cym)ClPF6 (1PF6) with an unreduced N:N double bond at d(NN) = 1.269(4) \AA and the sym. dinuclear (acac)2Ru2.5(m-abpy·-)Ru2.5(acac)2 with d(NN) = 1.372(4) \AA (rac isomer) support the above assignment for 2+ as an asym. mixed-valent configuration bridged by a radical ligand. Reversible one-electron oxidn. leads to a dication, 22+, with largely metal-centered spin (EPR: g1 = 2.207, g2 = 2.155, and g3 = 1.929), and a weak intervalence charge-transfer absorption at 1700 nm, as obsd. by spectroelectrochem. These results support a description of 22+ as (acac)2Ru1III(m-abpy0)Ru2II(Cym)Cl2+. D. functional theory (DFT) calcns. suggest that the first redn. of 2PF6 also involves the bridging ligand, leading to (acac)2Ru1III(m-abpy2-)Ru2II(Cym)Cl (2). Exptl., the first redn. of 2+ is not fully reversible, with evidence for the loss of chloride to form (acac)2Ru1(m-abpy)Ru2(Cym)+ (2a+; g1 = 2.454, g2 = 2.032, and g3 = 1.947). Further redn. produces (acac)2Ru1II(m-abpy2-)Ru2II(Cym) (2a), which forms (acac)2Ru1II(m-abpy2-)Ru2I(Cym)-/(acac)2RuII(m-abpy·-)Ru0(Cym)- (2a-) in yet another one-electron step (g1 = 2.052, g2 = 2.008, and g3 = 1.936). The major electronic transitions for each redox state have been assigned by time-dependent DFT calcns. on SciFinder(R)

@article{Das.2012, abstract = {The asym. dinuclear complex [(acac)2Ru1(\textgreek{m}-abpy)Ru2(Cym)Cl]PF6 ([2]PF6), with acac- = acetylacetonato = 2,4-pentanedionato, abpy = 2,2'-azobis(pyridine), and Cym = p-cymene = 1-isopropyl-4-methylbenzene, has been obtained from the mononuclear precursors [Ru(acac)2(abpy)] and [Ru(Cym)Cl2]2. X-ray crystal structure anal. suggests the oxidn. state formulation [(acac)2Ru1III(\textgreek{m}-abpy·-)Ru2II(Cym)Cl]+ for 2+, with antiferromagnetic coupling between one RuIII center and the radical-anion bridging ligand (abpy·-), based on the N-N distance of 1.352(3) {\AA}. As appropriate refs., the newly synthesized mononuclear [(abpy)RuII(Cym)Cl]PF6 ([1]PF6) with an unreduced N:N double bond at d(NN) = 1.269(4) {\AA} and the sym. dinuclear [(acac)2Ru2.5(\textgreek{m}-abpy·-)Ru2.5(acac)2] with d(NN) = 1.372(4) {\AA} (rac isomer) support the above assignment for 2+ as an asym. mixed-valent configuration bridged by a radical ligand. Reversible one-electron oxidn. leads to a dication, 22+, with largely metal-centered spin (EPR: g1 = 2.207, g2 = 2.155, and g3 = 1.929), and a weak intervalence charge-transfer absorption at 1700 nm, as obsd. by spectroelectrochem. These results support a description of 22+ as [(acac)2Ru1III(\textgreek{m}-abpy0)Ru2II(Cym)Cl]2+. D. functional theory (DFT) calcns. suggest that the first redn. of [2]PF6 also involves the bridging ligand, leading to [(acac)2Ru1III(\textgreek{m}-abpy2-)Ru2II(Cym)Cl] (2). Exptl., the first redn. of 2+ is not fully reversible, with evidence for the loss of chloride to form [(acac)2Ru1(\textgreek{m}-abpy)Ru2(Cym)]+ (2a+; g1 = 2.454, g2 = 2.032, and g3 = 1.947). Further redn. produces [(acac)2Ru1II(\textgreek{m}-abpy2-)Ru2II(Cym)] (2a), which forms [(acac)2Ru1II(\textgreek{m}-abpy2-)Ru2I(Cym)]-/[(acac)2RuII(\textgreek{m}-abpy·-)Ru0(Cym)]- (2a-) in yet another one-electron step (g1 = 2.052, g2 = 2.008, and g3 = 1.936). The major electronic transitions for each redox state have been assigned by time-dependent DFT calcns. [on SciFinder(R)]}, added-at = {2019-07-15T13:41:23.000+0200}, author = {Das, Amit and Scherer, Thomas Michael and Chowdhury, Abhishek Dutta and Mobin, Shaikh M. and Kaim, Wolfgang and Lahiri, Goutam Kumar.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2d87a569fb1f8ef9259601f8e40a99a83/b_schwederski}, doi = {10.1021/ic201975h}, interhash = {e20e487cdd215661484e887cc6880678}, intrahash = {d87a569fb1f8ef9259601f8e40a99a83}, issn = {0020-1669}, journal = {Inorganic Chemistry}, keywords = {asym azobis calcn cationic complex complex;mol cymene mol prepn pyridine ruthenium structure structure;crystal}, number = 3, pages = {1675--1684}, timestamp = {2019-07-15T11:42:10.000+0200}, title = {Asymmetrical Diruthenium Complex Bridged by a Redox-Active Ligand}, volume = 51, year = 2012 }