Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

A water-soluble cobalt phthalocyanine complex with sulfonate groups (CoPcTS) serves as an effective homogenous catalyst for photochemical water oxidation using a [Ru(bpy)₃]²⁺/S₂O₈²⁻ photosystem.

DOI： 10.1039/d2cc01985j

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Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.inorgchem.1c00293

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A doubly N-confused hexaphyrin dinuclear cobalt complex (Co2DNCH) is revealed as an efficient water oxidation catalyst, outperforming the mononuclear cobalt porphyrin with the same aryl group as those in Co2DNCH. By photoirradiation of a water/acetone-d(6) (9:1) mixture containing Co2DNCH, [Ru-II(bpy)(3)](2+), and S2O82- as the water oxidation catalyst, photosensitizer, and sacrificial electron acceptor, respectively, with visible light, O-2 was obtained as the maximum with turnover number = 1200, turnover frequency = 3.9 s(-1), and quantum yield = 0.30.

DOI： 10.1021/acs.inorgchem.0c02602

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The [{Fe(Me(3)tacn)}(2)(mu-P2O7)(mu-HPO4)]center dot 12H(2)O dinuclear Fe-2(III, III) complex was prepared. The HPO42- bridge in the complex arises from hydrolysis of the pyrophosphate bound to the Fe(III) centers in the trinuclear [{Fe(Me(3)tacn)}(3)-(P2O7)(2)](+) intermediate. Electrochemical reduction of this complex at pH < 3.2 results in dissociation of the H2PO4 bridge.

DOI： 10.1246/bcsj.20170427

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

We synthesized 1,8-bis(2,2':6',2"-terpyrid-4'-yl)anthraquinone (btpyaq) as a new dimerizing ligand and determined its single crystal structure by X-ray analysis. The dinuclear Ruthenium complex [Ru-2(mu-Cl)(bpy)(2)(btpyaq)](BF4)(3) ([3](BF4)(3), bpy = 2,2'-bipyridine) was used as a catalyst for water oxidation to oxygen with (NH4)(2)[Ce(NO3)(6)] as the oxidant (turnover numbers = 248). The initial reaction rate of oxygen evolution was directly proportional to the concentration of the catalyst and independent of the oxidant concentration. The cyclic voltammogram of [3](BF4)(3) in water at pH 1.3 showed an irreversible catalytic current above +1.6 V (vs. SCE), with two quasi-reversible waves and one irreversible wave at E-1/2 = +0.62, +0.82 V, and E-pa = +1.13 V, respectively. UV-vis and Raman spectra of [3](BF4)(3) with controlled-potential electrolysis at +1.40 V revealed that [Ru(IV)=O O=Ru(IV)](4+) is stable under electrolysis conditions. [Ru(III), Ru(II)] species are recovered after dissociation of an oxygen molecule from the active species in the catalytic cycle. These results clearly indicate that an O-O bond is formed via [Ru(V)=O O=Ru(IV)](5+).

DOI： 10.3390/catal7020056

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

We prepared a new Ru-2(III, IV) complex containing a pyrophosphate as the dinucleating component, by the reaction between the mononuclear complex [Ru(Me(3)tacn)Cl-3] and Na4P2O7 center dot 10H(2)O in aqueous solution. Cyclic voltammetric measurement for the complex [{Ru(Me(3)tacn)}(2)(mu-O)(mu-P2O7)]PF6 (1) in aqueous solution revealed the formation of two species with higher oxidation states, such as [O=Ru(IV)Ru(IV)=O] and [O=Ru(IV)Ru(V)=O](+). Furthermore, this complex showed activity for water oxidation reaction with Ce(NH4)(2)(NO3)(6) as the chemical oxidant in acidic aqueous solution.

DOI： 10.1246/cl.160721

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

We prepared a new Ru(III) complex with a covalent bond between the central Ru and C of the ligand, [RuCl(dpp)(bpy)] Cl ([1] Cl, dpp= 2,6-dipyridylphenyl, bpy= 2,2'-bipyridine), through the reaction of [(eta(6)-C6H6) RuCl(bpy)] Cl with one equivalent of 1,3-di(pyrid-2-yl) benzene. X-ray analysis of a single crystal of [1](PF6), which was prepared via the anion exchange of [1] Cl, revealed the short Ru-C bond length of [1](+). [1] Cl was easily hydrolyzed in a neutral water solution to the hydroxo complex, [Ru(OH)(dpp)(bpy)](+) ([2](+)). Cyclic voltammetry of [1]+ showed that the Ru(II)/ Ru(III) potential of [1](+) was more negative than that of the 2,2': 6', 2"-terpyridine (trpy) analogue, [RuCl(bpy)(trpy)](ClO4), by -770 mV under the same conditions. Moreover, the Ru(V)= O species, which is a key intermediate of water oxidation, was produced by electrochemical oxidation of [2](+) at an extremely negative potential (+ 0.80 V vs. saturated calomel electrode). [2](+) catalyzed water oxidation at pH 2.5 with [Ru (bpy)(3)](3+) as the oxidant. 2,6-dipyridylphenyl as a strong s-electron donor ligand negatively shifted the oxidation potential of water.

DOI： 10.1002/slct.201600716

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A tetracopper(II) complex containing two oxalate anions in the metal-based host cavity, [Cu-4(L-py)(mu-ox)(2)](PF6)(2)center dot 2(2-PrOH), where ox(2-): oxalato (C2O42-), was prepared by reacting H2Lpy, a phenol-based tetranucleating macrocyclic ligand with four pyridylmethyl pendant arms, Cu(ClO4)(2)center dot 6H(2)O, and sodium oxalate (1:4:2 stoichiometry, respectively) in methanol, followed by exchange of the counteranion with excess of NH4PF6. Single-crystal X-ray diffraction of 1 revealed that two {Cu(II)Cu(II)} units, bridged by a phenolato group of L-py(2-), were connected by two oxalato anions, to construct a rectangular "{CuCu}(mu-ox)(2){CuCu}" tetranuclear framework. This rectangular framework was maintained in DMF solution. The magnetic measurement of 1 in the 2-300 K range revealed antiferromagnetic behavior. The antiferromagnetic interaction in this complex occurs between the Cu(II) centers bridged by an oxalate (J = -140 cm(-1)).

DOI： 10.1246/bcsj.20150338

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A bis-hydroxo-bridged dinuclear Co-III-pyridylmethylamine complex (1) was synthesized and the crystal structure was determined by X-ray crystallography. Complex 1 acts as a homogeneous catalyst for visible-light-driven water oxidation by persulfate (S2O82-) as an oxidant with [Ru-II(bpy)(3)](2+) (bpy = 2,2'-bipyridine) as a photosensitizer affording a high quantum yield (44%) with a large turnover number (TON = 742) for O-2 formation without forming catalytically active Co-oxide (CoOx) nanoparticles. In the water-oxidation process, complex 1 undergoes proton-coupled electron-transfer (PCET) oxidation as a rate-determining step to form a putative dinuclear bis-mu-oxyl Co-III complex (2), which has been suggested by DFT calculations. Catalytic water oxidation by 1 using [Ru-III(bpy)(3)](3+) as an oxidant in a (H2O)-O-16 and (H2O)-O-18 mixture was examined to reveal an intramolecular O-O bond formation in the two-electron-oxidized bis-mu-oxyl intermediate, prior to the O-2 evolution.

DOI： 10.1021/acs.inorgchem.5b02336

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Platinum complexes with 1,4,7-triazacyclononane (tacn) as facial ligands, [(PtCl3)-Cl-Iv(tacn)](ClO4), [(PtCl)-Cl-Iv(bpy)-(tacn)](ClO4)(3) ([1](ClO4), and [2](ClO4)(3), bpy: 2,2'-bipyridine) were prepared, and their hexa-coordinated octahedral structures were determined via single-crystal X-ray analysis. In aqueous solutions containing NaCl as the electrolyte, [2](3+) exhibited a quasi-reversible two-electron redox wave at +0.22 V (vs. SCE) with a large peak separation Delta E = E-pc - E-pa = 0.28 V). In addition, controlled-potential reduction of [2](3+) at -0.30 V in aqueous solutions containing NaCl afforded [Pt-II(bpy)(tacn)](2+) ([3](2+)), which was then re-oxidized to regenerate [2](3+). X-ray analysis of [3](2+) revealed a tetra-coordinated square-planar structure in which both tacn and bpy were bound to the central Pt as bidentate ligands. The redox potential of this reaction is coupled with dissociation/association of Cl- from/to Pt in the solution. MO/DFT calculations indicate that structural changes in tacn promote the reversible two-electron redox reaction between the octahedral Pt(IV) and square planar Pt(II) complexes.

DOI： 10.1246/bcsj.20150097

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Authorship：Lead author   Language：English   Publishing type：Part of collection (book)   Publisher：Wiley Blackwell  

The possible reaction path for O-O bond formation has been a point of contention among investigators of water oxidation, but there is a growing consensus acknowledging two main pathways: (1) a nucleophilic attack of water on a high-valent metal-oxo species, and (2) a coupling reaction of two metal-oxo species to give μ-peroxide intermediates. This chapter summarizes the novel features of the dinuclear and related mononuclear Ruthenium (Ru) species with quinone ligands. It also summarizes the comparison of their properties with those of the Ru analogs in which the bpy ligand replaces quinone. The chapter explains electrochemical water oxidation using the Tanaka catalyst. It further discusses the acid-base equilibrium and redox behavior of mononuclear Ru-aqua complexes with a variety of dioxolene ligands. The more complicated redox and catalytic properties of the Tanaka catalyst and its related dinuclear complexes are explained.

DOI： 10.1002/9781118698648.ch5

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Dinuclear cobalt-1,10-phenanthroline (1) and 2,2'-bipyridine (2) complexes bridged by 1,8-bis(2,2':6',2 ''-terpyrid-4'-yl)anthracene (btpyan) were prepared. Both of the complexes selectively catalysed the electrochemical four-electron reduction of dioxygen to H2O without the generation of H2O2 as a two-electron reduction product.

DOI： 10.1039/c2cc36528f

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A tetranucleating macrocyclic ligand bearing four acetate pendants, L6-, was newly yielded by a stepwise synthesis from [Zn-4(L')(AcO)(2)(OH)(2)](ClO4)(2)center dot H2O (1), which was prepared from [2 + 2] Schiff-base condensation of 2,6-diformyl-4-methylphenol and 1,2-bis(2-aminoethoxy)ethane in the presence of Zn(ClO4)(2)center dot 6H(2)O, sodium acetate, and triethylamine. A mu(4)-oxo tetracopper(II) complex [Cu-4(L)(mu(4)-O)]center dot H2O (2) was obtained from the reaction of Cu(ClO4)(2)center dot 6H(2)O and Na2H4L in methanol under basic conditions, and characterized by X-ray crystallography. Two adjacent copper centers were bridged by the phenoxo oxygen of L6- to form [Cu20.1-0Ph)] unit, two pairs of which were further linked by an oxo anion with a distorted tetrahedral geometry, finally creating a tetracopper core [(Cu-2-mu-OPh)}(2)(mu(4)-O)]. Cryomagnetic measurements of 2 in the range of 2-300 K exhibited antiferromagentic behavior. Magnetic analysis of 2 was carried out by the four spin-exchange interactions model based on the bridging mode and the Cu-(mu(4)-O)-Cu angles, J(A): Cu1/Cu4, J(B): Cu2/Cu3, J(C): Cu1/Cu2 and Cu3/Cu4, and J(D): Cu1/Cu3 and Cu2/Cu4 pairs. The estimated four magnetic exchange interactions (J(A), J(B), J(C), and J(D)) were -17, -161, -108, and -109 cm(-1), respectively.

DOI： 10.1246/bcsj.20120084

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

A bis(rutheniumbipyridine) complex bridged by 1,8-bis(2,2':6',2''-terpyrid-4'-yl)anthracene (btpyan), [Ru2(mu-Cl)(bpy)2(btpyan)](BF4)3 ([1](BF4)3; bpy=2,2'-bipyridine), was prepared. The cyclic voltammogram of [1](BF4)3 in water at pH 1.0 displayed two reversible [RuII,RuII]3+/[RuII,RuIII]4+ and [RuII,RuIII]4+/[RuIII,RuIII]5+ redox couples at E1/2(1)=+0.61 and E1/2(2)=+0.80 V (vs. Ag/AgCl), respectively, and an irreversible anodic peak at around E=+1.2 V followed by a strong anodic currents as a result of the oxidation of water. The controlled potential electrolysis of [1]3+ ions at E=+1.60 V in water at pH 2.6 (buffered with H3PO4/NaH2PO4) catalytically evolved dioxygen. Immediately after the electrolysis of the [1]3+ ion in H216O at E=+1.40 V, the resultant solution displayed two resonance Raman bands at $\tilde \nu $=442 and 824 cm-1. These bands shifted to $\tilde \nu $=426 and 780 cm-1, respectively, when the same electrolysis was conducted in H218O. The chemical oxidation of the [1]3+ ion by using a CeIV species in H216O and H218O also exhibited the same resonance Raman spectra. The observed isotope frequency shifts (?$\tilde \nu $=16 and 44 cm-1) fully fit the calculated ones based on the Ru?O and O?O stretching modes, respectively. The first successful identification of the metal?O?O?metal stretching band in the oxidation of water indicates that the oxygenoxygen bond at the stage prior to the evolution of O2 is formed through the intramolecular coupling of two Ruoxo groups derived from the [1]3+ ion.

DOI： 10.1002/chem.201102236

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The bridging ligand, 1,8-bis(2,2':6',2 ''-terpyrid-4'-yl)anthracene (btpyan) was synthesized by the Miyaura-Suzuki cross coupling reaction of anthracenyl-1,8-diboronic acid and 4'-triflyl-2,2': 6'-2 ''-terpyridine in the presence of Pd(PPh3)(4) (5 mol%) with 68% in yield. Three ruthenium-dioxolene dimers, [Ru-2(OH)(2)(dioxolene)(2)(btpyan)](0) (dioxolene = 3,6-di-tert-butyl-1,2-benzosemiquinone ([1](0)), 3,5-dichloro-1,2-benzosemiquinone ([2](0)) and 4-nitro-1,2-benzosemiquinone ([3](0))) were prepared by the reaction of [Ru2Cl6(btpyan)](0) with the corresponding catechol. The electronic structure of [1](0) is approximated by [Ru-2(II)(OH)(2)(sq)(2)(btpyan)](0) (sq = semiquinonato). On the other hand, the electronic states of [2](0) and [3](0) are close to [Ru-2(III)(OH)(2) (cat)(2)(btpyan)](0) (cat = catecholato), indicating that a dioxolene having electron-withdrawing groups stabilizes [Ru-2(III)(OH)(2)(cat)(2)(btpyan)](0) rather than [Ru-2(II)(OH)(2)(sq)(2)(btpyan)](0) as resonance isomers. No sign was found of deprotonation of the hydroxo groups of [1](0), whereas [2](0) and [3](0) showed an acid-base equilibrium in treatments with t-BuOLi followed by HClO4. Furthermore, controlled potential electrolysis of [1](0) deposited on an ITO (indium-tin oxide) electrode catalyzed the four-electron oxidation of H2O to evolve O-2 at potentials more positive than +1.6 V (vs. SCE) at pH 4.0. On the other hand, the electrolysis of [2](0) and [3](0) deposited on ITO electrodes did not show catalytic activity for water oxidation under similar conditions. Such a difference in the reactivity among [1](0), [2](0) and [3](0) is ascribed to the shift of the resonance equilibrium between [Ru-2(II)(OH)(2)(sq)(2)(btpyan)](0) and [Ru-2(III)(OH)(2)(cat)(2)(btpyan)](0).

DOI： 10.1039/c0dt00977f

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Electrochemical oxidation of [Ru-II(terpy)(sq)(NH3)](+) in neutral water (pH 8.0) at +0.8 V (versus SCE) generated [Ru-II(terpy)(q)(NH2 center dot)](2+) and/or [Ru-III(terpy)(sq)(NH2 center dot)](2+) (terpy = 2,2':6',2 ''-terpyridine, sq = 3,5-di-tert-butyl-1,2-semiquinonate, q = 3,5-di-tert-butyl-1,2-benzoquinone), which played roles in hydrogen abstraction and one-electron acceptor in the catalytic oxidation of methanol, ethanol, and 2-propanol affording formaldehyde, acetoaldehyde, and acetone, respectively, under the electrolysis conditions. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2010.11.013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Electrochemical reduction of a diazonium complex [Ru-(bpy)(trpy-ph-N-2(+))(CO)](PF6)(3) ([1](PF6)(3)) (bPY = dine, trpy-ph-N-2(+) = 4-(2,2' 6',2"-terpyncline-4'-yl)benzenedi-azonium) using a GC electrode forms multdayer films of the complexes on the electrode surface, on which the reduced form of the complex showed strong affinity toward CO2

DOI： 10.1246/cl.2010.1134

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The (iminium ion)ruthenium(II) complex mer(Cl, Cl,Cl)-[RuCl3{eta(2)-NCHCH(2)py(C(2)H(4)py)C2H5}] was synthesized via a C-H activation of the bridging ethyl group of an ethylbis(2-pyridylethyl)amine ligand and characterized by X-ray structural analysis. Oxidations of alcohols by the (iminium ion)ruthenium(11) complex occurred with generation of mer-[(RuCl3)-Cl-III(ebpea)].

DOI： 10.1021/om100161r

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The ruthenium complexes [Ru(bpy)(pbn)(2)](PF6)(2) ([2](2+); bpy = 2,2'-bipyridine, pbn = 2-(2-pyridyl)benzo[b]-1,5-naphthyridine) and [Ru(pbn)(3)](PF6)(2) ([3](2+)) were synthesized. Photoirradiation (lambda > 420 nm) of [2](2+) and [3](2+) in CH3CN/triethanolamine (TEOA) brought about proton coupled four-and six-electron reduction of the complexes to produce [Ru(bpy)(pbnH(2))(2)](PF6)(2) ([2.H-4](2+); pbnH(2) = 5,10-dihydro-2-(2-pyridyl)benzo[b]-1,5-naphthyridine) and [Ru(pbnH(2))(3)](PF6)(2) ([3.H-6](2+)), respectively. The photoexcited [Ru-III(bpy)(pbn(center dot-))(pbnH(2))](2+) intermediate is quenched by intermolecular electron transfer from TEOA to Ru-III, while intramolecular transfer from pbnH(2) to Ru-III is negligible. As a result, novel photochemical four-and six-electron reduction of [2](2+) and [3](2+) is achieved through repetition of the two-electron reduction of the Ru-pbn group. The high efficiency photochemical two-, four- and six-electron reductions of [Ru(bpy)(2)(pbn)](2+) ([1](2+)), [2](2+) and [3](2+), respectively, by taking advantage of proton coupled two electron reduction of NAD(+) analogous type ligands such as pbn opens a general pathway for multi-electron reduction of metal complexes via illumination with visible light.

DOI： 10.1039/c0dt00504e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A polypyridylruthenium complex with an NAD(+)/NADH model ligand, [Ru(bpy)(2)(pbn)](2+) [bpy = 2,2'-bipyridine, pbn = 2-(2-pyridyl)benzo[b]-1,5-naphthyridine] in a D2O/CH3CN/triethylamine solution, undergoes stereospecific hydrogenation to give Delta-(S)- and Lambda-(R)- [Ru(bpy)(2)(pbnDD)](2+) [pbnDD = 5,10-dideutero-2-(2-pyridyl)benzo[b]-1,5-naphthyridine] upon visible-light irradiation. This result clearly indicates the pathway via the pi-stacked dimer of the deuterated one-electron-reduced species. The reduction of [Ru(bpy)(2)(pbn)](2+) with Na2S2O4 in D2O did not afford any stereospecific products. Furthermore, the more sterically crowded Ru complex, [Ru(dmb)(2)(pbn)](2+) (dmb = 6,6'-dimethyl-2,2'-bipyridine), did not produce the corresponding pbnDD species upon irradiation.

DOI： 10.1021/ic901935u

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The redox states of Ru(OH2)(Q) (tpy)(2+) (Q = 3,5-di-tert-butyl-1,2-benzoquinone, tpy = 2,2':6',2 ''-terpyridine) are investigated through experimental and theoretical UV-vis spectra and Pourbaix diagrams. The electrochemical properties are reported for the species resulting from deprotonation and redox processes in aqueous solution. The formal oxidation states of the redox couples in the various intermediate complexes are systematically assigned using electronic structure theory. The controversy over the electronic assignment of ferromagnetic vs. antiferromagnetic coupling is investigated through comparison of ab initio methods and the broken-symmetry density functional theory (DFT) approach. The various pK(a) values and reduction potentials, including the consideration of proton-coupled electron-transfer (PCET) processes, are calculated, and the theoretical version of the Pourbaix diagram is constructed in order to elucidate and assign several previously ambiguous regions in the experimental diagram,

DOI： 10.1021/ic900057y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Tanaka and co-workers reported a novel dinuclear Ru complex, [Ru-2(OH)(2)(3,6-Bu(2)Q)(2)(btpyan)](SbF6)(2) (3,6-Bu(2)Q = 3,6-ditert-butyl-1,2-benzoquinone, btpyan = 1,8-bis(2,2':6',2"-terpyrid-4'-yl)anthracene), that contains redox active quinone ligands and has an excellent electrocatalytic activity for water oxidation when immobilized on an indium-tin-oxide electrode (Inorg. Chem., 2001, 40, 329-337). The novel features of the dinuclear and related mononuclear Ru species with quinone ligands, and comparison of their properties to those of the Ru analogues with the bpy ligand (bpy = 2,2'-bipyridine) replacing quinone, are summarized here together with new theoretical and experimental results that show striking features for both the dinuclear and mononuclear species. The identity and oxidation state of key mononuclear species, including the previously reported oxyl radical, have been reassigned. Our gas-phase theoretical calculations indicate that the Tanaka Ru-dinuclear catalyst seems to maintain predominantly Ru(II) centers while the quinone ligands and water moiety are involved in redox reactions throughout the entire catalytic cycle for water oxidation. Our theoretical study identifies [Ru-2(O-2(-))(Q(-1.5))(2)(btpyan)](0) as a key intermediate and the most reduced catalyst species that is formed by removal of all four protons before four-electron oxidation takes place. While our study toward understanding the complicated electronic and geometric structures of possible intermediates in the catalytic cycle is still in progress, the current status and new directions for kinetic and mechanistic investigations, and key issues and challenges in water oxidation with the Tanaka catalyst (and its analogues with Cl- or NO2- substituted quinones and a species with a xanthene bridge instead an antheracene) are discussed.

DOI： 10.1021/ic701892v

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Language：English   Publishing type：Research paper (international conference proceedings)  

Reversible conversion between carbon dioxide and MeOH through six-electron redox reactions is one of the feasible pathway to construct renewable societies. Metal complexes that can oxide MeOH at potentials more negative than four-electron reduction of dioxygen are candidates for the electrode materials in fuel-cells. An aqua-Ru complex having a quinone ligand (pKa = 5.5) exists as the hydroxy analog (pKa ca. 11) in neutral water, and the latter is converted to an oxyl radical complex with a semiquinone ligand in highly basic solutions due to the electron flow from the deprotonated hydroxy group to the quinone ligand. On the other hand, an Ru-aminyl radical complex with quinone derived from the corresponding Ru-amine one works as an active catalyst in the electrochemical oxidation of MeOH in the presence of base at 0.3 V (vs. SCE). We will also discuss the electrochemical reduction of carbon dioxide catalyzed by Ru complexes in the symposium.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Aminyl radicals may one day be useful oxidn. catalysts if their thermodn. instability can be overcome, for example, through complexation with a metal. Deprotonation of the semiquinonato-anilido complex [RuIII(NHPh-bpa)(tBu2sq)]+ (1; NHPh-bpa = 2-(bis(pyridylmethyl)aminomethyl)-anilido ligand; tBu2sq- = 3,5-di-tert-butylsemiquinonate) leads to formation of the semiquinonato-anilino-radical complex [RuII(·NPh-bpa)(tBu2sq)] (2). Electrochem. redn. of 2 leads to formation of the catecholato-anilino radical complex [RuII(·NPh-bpa)(tBu2cat)]- (3). Treatment of 1 with MeSO3H gave the semiquinone-aniline complex [RuIII(NH2Ph-bpa)(tBu2sq)]2+ (4). The complexes were studied using cyclic voltammetry, EPR, magnetic susceptibility and DFT calcns.

DOI： 10.1002/anie.200701600

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

DOI： 10.1002/anie.200701600

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The mononuclear Ru(II) complex, [Ru(bbnp)(terp)]2+ (bbnp = 2,6-bis(benzo[b]-1,5-naphthyridin-6-yl)-4-tert-butylpyridine and terpy = 2,2:6',2''-terpyridine) is reversibly converted into the 4-electron-reduced form [1-H4]2+ through electrochem. and photochem. redox reactions in aq. soln. The 2,6-bis(benzo[b]-1,5-naphthyridin-6-yl)-4-tert-butylpyridine ligand acts alternatively as a reservoir/source of 4 electrons or 4 protons.

DOI： 10.1002/anie.200701204

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The photochem. and electrochem. properties of a polypyridylruthenium complex with an NAD+/NADH (NAD+ = NAD) model ligand, [Ru(bpy)2-(pbn)]2+ ([1]2+; bpy = 2,2'-bipyridine, pbn = 2-(2-pyridyl)benzo[b]-1,5-naphthyridine), were investigated. When solns. contg. [1]2+ and triethylamine are irradiated with visible light, [(1)HH]2+ is produced cleanly.

DOI： 10.1002/anie.200700304

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A series of ruthenium complexes [ Ru( OAc)( dioxolene)( terpy)] having various substituents on the dioxolene ligand ( dioxolene) 3,5-t-Bu2C6H2O2 ( 1), 4-t-BuC6H3O2 ( 2), 4-ClC6H3O2 ( 3), 3,5-Cl2C6H2O2 ( 4), Cl4C6O2 ( 5); terpy) 2,2': 6'2 ''-terpyridine) were prepared. EPR spectra of these complexes in glassy frozen solutions ( CH2Cl2: MeOH = 95: 5, v/v) at 20 K showed anisotropic signals with g tensor components 2.242 > g(1) > 2.104, 2.097 > g(2) > 2.042, and 1.951 > g(3) > 1.846. An anisotropic value, < g > = g(1) - g(3), and an isotropic g value, < g > [( g(1)(2) + g(2)(2) + g(3)(2))/3](1/2), increase in the order 1 < 2 < 3 < 4 < 5. The resonance between the Ru-II( sq) ( sq = semiquinone) and RuIII( cat) ( cat) catecholato) frameworks shifts to the latter with an increase of the number of electron-withdrawing substituents on the dioxolene ligand. DFT calculations of 1, 2, 3, and 5 also support the increase of the Ru spin density ( RuIII character) with an increase of the number of Cl atoms on the dioxolene ligand. The singly occupied molecular orbitals ( SOMOs) of 1 and 5 are very similar to each other and stretch out the Ru - dioxolene frameworks, whereas the lowest unoccupied molecular orbital ( LUMO) of 5 is localized on Ru and two oxygen atoms of dioxolene in comparison with that of 1. Electron-withdrawing groups decrease the energy levels of both the SOMO and LUMO. In other words, an increase in the number of Cl atoms in the dioxolene ligand results in an increase of the positive charge on Ru. Successive shifts in the electronic structure between the RuII( sq) and RuIII( cat) frameworks caused by the variation of the substituents are compatible with the experimental data.

DOI： 10.1021/ic060696i

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A platinum-ruthenium dinuclear complex, [(PtCl){RuCl((t)Bu(2)sq)}(btpyxa)](2+) ([2](2+)) (btpyxa = 2,7-di-tert-butyl-9.9-dimethyl-4,5-bis(2,2':6',2 ''-terpyrid-4'-yl)xanthene, (t)Bu(2)sq = 3,5 -di-tert-butyl-1,2-benzosemiquinonateion), in which btpyxa acts as a bridging ligand, was prepared, and its physical properties were compared to those of an analogous dmso complex, [(PtCl){Ru((t)Bu(2)sq)(dmso)}(btpyxa)](2+) ([1](2+)) (dmso = dimethyl sulfoxide). Treatment of complex [1](2+) with an aqueous NaOH solution followed by 2-aminoethanethiol afforded [{Pt(SCH2CH2NH2)}{Ru((t)Bu(2)sq)(dmso))(btpyxa)](2+) ([3](2+)). On the other hand, the reaction of complex [2](2+) with 2-arninoethanethiol produced [{Pt(SCH2CH2NH2)}Ru((t)Bu(2)sq)}(btpyxa)](2+) ([4](2+)), in which Pt and Ru atoms are bridged by the 2-aminoethanethiolato ligand. Complex [4](2+) was also obtained by heating complex [3](2+) in 2-methoxyethanol.

DOI： 10.1246/bcsj.79.1535

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A ruthenium-dioxolene-amine complex, [Ru-III(NH2L)(Bu(2)sq)](PF6)(2)center dot 0.5H(2)O (NH2-L = bis(2-pyridylmethyl)2-aminoethylamine, Bu(2)sq(-) = 15-di-tert-butylsemiquinonate). was newly prepared. The complex undergoes spontaneous one-electron reduction under basic conditions in MeOH and works as an electrocatalyst in the oxidation of benzyl alcohol to benzaldehyde under electrolysis at +0.4V (vs SCE).

DOI： 10.1246/bcsj.79.745

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A platinum(II) complex bearing 1,10-phenanthroline-5,6-dione (phenO(2)), [PtCl(phenO(2)-N,N')(PPh3)](+) ([2](+)) was newly prepared and characterized. An X-ray crystallographic study of [2](PF6) revealed that the phenO(2) ligand coordinates to platinum with the N,N'-chelate form. The basicity of the quinoid part of phenO(2) in [2](+) and of the diimine one in [Pt(phenO(2)-O,O')(PPh3)(2)] with an O,O'-chelate ring (3) was evaluated in the absence and the presence of Li+ by means of UV-vis spectroscopy and cyclic voltammetry. The quinoid group in [2](+) practically had no ability to bind Li+, but induced on anodic potential shift of the phenO(2) localized redox potential by 850 mV due to the strong interaction between the reduced form of [2](+) and Li+. Undeniably, a weak interaction of Li+ with the diimine moiety of free phenO(2) (K = 3.6 M-1) is greatly enhanced in the interaction between Li+ and the diimine site in 3 because of the electron donation from the catecholato group of the complex.

DOI： 10.1246/bcsj.79.106

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Language：English   Publishing type：Research paper (scientific journal)  

A ruthenium-dioxolene-amine complex, [RuIII(NH 2-L)(Bu2sq)](PF6)2·0.5H 2O (NH2-L = bis(2-pyridylmethyl)-2-aminoethylamine, Bu2sq- = 3,5-di-tert-butylsemiquinonate), was newly prepared. The complex undergoes spontaneous one-electron reduction under basic conditions in MeOH and works as an electrocatalyst in the oxidation of benzyl alcohol to benzaldehyde under electrolysis at +0.4 V (vs SCE). © 2006 The Chemical Society of Japan.

DOI： 10.1246/bcsj.79.745

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Language：English   Publishing type：Research paper (scientific journal)  

A platinum-ruthenium dinuclear complex, [(PtCl){RuCl( tBu 2sq)}(btpyxa)] 2+ ([2] 2+) (btpyxa = 2,7-di-tert-butyl-9,9-dimethyl-4,5-bis(2,2′:6′,2″-terpyrid- 4′-yl)xanthene, tBu 2sq = 3,5-di-tert-butyl-1,2- benzosemiquinonate ion), in which btpyxa acts as a bridging ligand, was prepared, and its physical properties were compared to those of an analogous dmso complex, [(PtCl){Ru( tBu 2sq)(dmso)}(btpyxa)] 2+ ([1] 2+) (dmso = dimethyl sulfoxide). Treatment of complex [1] 2+ with an aqueous NaOH solution followed by 2-aminoethanethiol afforded [{Pt(SCH 2CH 2NH 2)}{Ru( tBu 2sq)-(dmso)}(btpyxa)] 2+ ([3] 2+). On the other hand, the reaction of complex [2] 2+ with 2-aminoethanethiol produced [{Pt-(SCH 2CH 2NH 2)Ru( tBu 2sq)}(btpyxa)] 2+ ([4] 2+), in which Pt and Ru atoms are bridged by the 2- aminoethanethiolato ligand. Complex [4] 2+ was also obtained by heating complex [3] 2+ in 2-methoxyethanol. © 2006 The Chemical Society of Japan.

DOI： 10.1246/bcsj.79.1535

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The bis(chlororuthenium) complex [RU2Cl2(3,6-tBu(2)sq)(2-)(btpyxa)](PF6)(2) [1](PF6)(2) [3,6-tBu(2)sq = 3,6-di-tert-butyl-1,2-benzosemiquinone; btpyxa = 2,7-di-tert-butyl-9,9-dimethyl-4,5-bis(2,2':6',2"-terpyrid-4'-yl)xanthene] and the oxobridged diruthenium complex [Ru-2(mu-O)(3,6-tBu(2)sq)(2)-(btpyxa)](PF6)(3) [2](PF6)(3) were synthesized, and the redox behavior of these complexes, which contain a non-innocent dioxolene ligand, was investigated by electrochemical and electrospectrochemical methods. Dicationic [1](2+) undergoes two successive metal-centered one-electron and a simultaneous two-electron ligand-based redox reaction at E-1/2 = +0.13 and +0.09 and E-1/2 = -0.75 V (vs. SCE), respectively, in CH2Cl2. The UV/Vis/NIR spectrum of tricationic [2](3+) shows an intervalence-transition (IT) band at 1333 nm (epsilon = 1.52 x 10(4) M-1 cm(-1)) in a near-IR region together with two CT bands at 766 (epsilon = 2.21 x 10(4) M(-1)cm(-1)) and 586nm (c = 1.13 x 104 M-1 cm(-1)) in CH2Cl2. The mixed-valence complex of [2 ](3+) with an Ru-IV-O-Ru-III core is reversibly oxidized and reduced to the Ru-IV-Ru-IV and Ru-ll-Ru-ll oxidation states at E-1/2 = +0.63 and -0.01 V, respectively, in CH2Cl2. On the other hand, three-electron reduction of [2](PF6)(3) is accompanied by the cleavage of the Ru-O-Ru bond at E-p = +0.02 V to give [(Ru(OMe)(3,5-tBU(2)sq))(Ru(OH2)(3,5-tBU(2)sq))(btpyxa)](+) in MeOH. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

DOI： 10.1002/ejic.200500141

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The new Ru-dioxolene-ammine complexes, [Ru-II(NH3)-(sq)(trpy)](ClO4) (1, sq = 3,5-di-tert-butyl-1,2-benzoseiniquinone, trpy = 2,2:6,2"-terpyridine) and [Ru-III(NH3)(sq)(trpy)](ClO4)(2) (2), were prepared. They have an ability to oxidize MeOH and i-PrOH catalytically under very mild conditions such as the electrolysis at 0V (vs SCE) in CH2Cl2.

DOI： 10.1246/cl.2004.1596

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

4,5-Bis(terpyridyl)-2,7-di-tert-butyl-9,9-dimethylxanthene (btpyxa) was prepared to serve as a new bridging ligand via Suzuki coupling of terpyridin-4'-yl triflate and 2,7-di-teil-butyl-9,9-dimethylxanthene-4,5-diboronic acid. The reaction of btpyxa with either 1 equiv or an excess of PtCl2(cod) (cod = 1,5-cyclooctadiene) followed by anion exchange afforded mono- and dinuclear platinum complexes [(PtCl)(btpyxa)](PF6) ([1](PFO) and [(PtCl)(2)(btpyxa)](PF6)(2) ([2]-(PF6)(2)), respectively. The X-ray crystallography of [1](PF6)-CHCl3 revealed that the two terpyridine units in the ligand are nearly parallel to each other. The heterodinuclear complex [(PtCl){Ru((t)Bu(2)SQ)(dmso)}(btpyxa)](PF6)(2) ([4](PF6)(2)) (dmso = dimethyl sulfoxide; (t)Bu(2)SQ = 3,5-di-tert-butyl-1,2-benzosemiquinone) and the monoruthenium complex [Ru((t)Bu(2)SQ)(dmso)(trpy)](PF6) ([5](PF6)) (trpy = 2,2':6',2"-terpyridine) were also synthesized. The CV of [2](2+) suggests possible electronic interaction between the two Pt(trpy) groups, whereas such an electronic interaction was not suggested by the CV of [4](2+) between Pt(trpy) and Ru((t)Bu(2)SQ) frameworks.

DOI： 10.1021/ic049680n

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Monocarbonylruthenium complexes with a semiquinone ligand, ([Ru(CO)(sq)(L)(n+) (sq = 3,5-di-tert-butyl-1,2-benzosemiquinone. n = 1 or 0. L = 2,2':6',2"-terpyridine ([1](+)), 2,6-bis(N,N-dimethyIaminomethyl)pyridine ([2](+)), 2.6-di-2'-pyridylphenyl ([3](0)), or 2-(2,2'-bipyridin-6-yl)phenolato ([4](0))), and dicarbonylruthenium complexes with two semiquinone ligands, [Ru(CO2)(2)(sq)(2)] ([5](0)) and [Ru(CO)(2)(phsq)(2)] (phsq = 9,10-phenanthrasemiquinone, [6](0)), were synthesized and the structures of [1](+) and [6] were determined by X-ray crystal analysis. Monocarbonyl Ru(II)-dioxolene complexes displayed the ligand localized catecholato/semiquinone and semiquinone/quinone redox couples, and two sets of those redox couples were observed in the dicarbonyl Ru(II)-bis(dioxolene) complexes. Spectroelectrochemical study revealed that the Ru(II)-catecholato and Ru(II)-semiquinone complexes were stable in solutions, while the Ru(II)-quinone complexes underwent fragmentation in solutions. One-electron reduction of the rnonocarbonyl Ru(II)- was substantially larger semiquinone complexes caused a red shift of the nu(CO) bands in a range of 41 to 56 cm(-1), which was substantially larger than those of carbonyl Ru(II)-polypyridyl complexes. Two nu(CO) bands of dicarbonyl Ru(II)-bis(semiquinone) complexes also shifted to lower wavelength in a range of 53 to 99 cm(-1) upon two electron reduction of the complexes. The unusually large red shift of nu(CO) bands upon reduction of carbonyl Ru(II)-dioxolene complexes compared with those of Ru(II)-polypyridyl complex is ascribed to a strong electronic interaction between carbonyl and dioxolene ligands.

DOI： 10.1246/bcsj.77.741

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The syntheses and electrochemical properties of novel ruthenium(II) polypyridyl complexes with 4,4'-bipyrimidine, [Ru(trpy)(bpm)Cl](X) ([1](X; X = PF6-, BF4-)) and with a quaternized 4,4'-bipyrimidinium ligand, [Ru(trpy)(Me(2)bpm)Cl](BF4)(3) ([2](BF4)3) (trpy = 2,2':6',2"-terpyridine, bpm = 4,4'-bipyrimidine, Me(2)bpm = 1,1'-dimethyl-4,4'-bipyrimidinium) are presented. The bpm complex [1](divided by) was prepared by the reaction of Ru(trpy)Cl-3 with 4,4'-bipyrimidine in EtOH/H2O. The structural characterization of [1](divided by) revealed, that the bpm ligand coordinated to the ruthenium atom with the bidentate fashion. Diquaternization of the noncoordinating nitrogen atoms on bpm of [1](divided by) by (CH3)(3)OBF4 in CH3CN gave [2](BF4)(3). The electrochemical and spectroelectrochemical properties of the complexes are described. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2003.10.015

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Syntheses and pH dependent electrochemical properties of aqua-ruthenium(II) complexes, [Ru(trpy)(PDA-N,N')-(OH2)](ClO4)(2) ([1](ClO4)(2)) and [Ru(trpy)(PD-N,N')(OH2)](ClO4)(2) ([2](ClO4)(2)) (trpy = 2,2':6',2"-terpyridine, PDA = 6-acetonyl-6-hydroxy-1,10-phenanthroline-5-one, PD = 1,10-phenanthroline-5,6-dione) are presented. Treatment of [Ru(trpy)(PD-N,N')Cl](PF6) with AgClO4 in a mixed solvent of acetone and H2O selectively produced the acetonyl-PD complex [1](ClO4)(2), and the similar treatment in a mixed solvent of 2-methoxyethanol and H2O gave the PD complex[2](ClO4)(2). The molecular structures of both complexes were determined by X-ray structural analysis. The proton dissociation constants of various oxidations state of [1](2+) and [2](2+) were evaluated by simulation of E-1/2 values of those redox potentials depending on pH. The simulation revealed that the acetonyl-PD complex[1](2+) underwent successive Ru(II)/Ru(III) and Ru(III)/Ru(IV) redox couples though the two redox reactions were not separated in the cyclic voltammograms. The redox behavior of [2](2+) in H2O is reasonably explained by not only the similar successive metal-centered redox reactions but also simultaneous two-electron quinone/catechol redox couple of the PD ligand including the contribution of hydration on a carbonyl carbon.

DOI： 10.1039/b312310c

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The synthesis and electrochemical properties of a Ru(II) complex having a redox active ligand, 1,10-phenanthroline-5,6-dione, [Ru(trpy)(PD-N,N')Cl](PF6) ([1](PF6)), and mixed-metal complexes [(PPh3)(2)Pd(O,O'-PD-N,N')Ru(trpy)-Cl](PF6) ([2](PF6)) and [(PPh3)(2)Pt(O,O'-PD-N,N')Ru(trpy)Cl](PF6) ([3](PF6)) (trpy = 2,2':6',2"-terpyridine, PD = 1,10-phenanthroline-5,6-dione) are presented. The complex of [1](+), which was prepared by the reaction of Ru(trpy)(DMSO)Cl-2 with PD in hot ethanol, underwent two reversible reductions in the PD-based redox reactions. The quinoid moiety of [1](+) was endowed with coordination ability to metals by one- and two-electron reduction of the complex. The mixed-metal complexes of [2](+) and [3](+) were synthesized by the reactions of [1](+) with M(PPh3)(4) (M = Pd, Pt), and both complexes have the [1](-) and M(II) frameworks.

DOI： 10.1039/b304912d

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The ruthenium oxyl radical complex, [Ru-II(trpy)(Bu(2)SQ)O.-] (trpy = 2,2':6',2"-terpyridine, Bu-2-SQ = 3,5-di-tert-butyl-1,2-benzosemiquinone) was prepared for the first time by the double deprotonation of the aqua ligand of [Ru-III(trpy)(Bu(2)SQ)(OH2)](ClO4)(2), [Ru-III(trpy)(BU2SQ)(OH2)](ClO4)(2) is reversibly converted to [Ru-III(trpy)(Bu(2)SQ)(OH-)](+) upon dissociation of the aqua proton (pK(a) 5.5). Deprotonation of the hydroxo proton gave rise to intramolecular electron transfer from the resultant O2- to Ru-dioxolene. The resultant [Ru-II(trpy)(Bu(2)SQ)O.-] showed antiferromagnetic behavior with a Ru-II-semiquinone moiety and oxyl radical, the latter of which was characterized by a spin trapping technique. The most characteristic structural feature of [Ru-II(trpy)(Bu(2)SQ)O.-] is a long Ru-O bond length (2.042(6) Angstrom) as the first terminal metal-O bond with a single bond length. To elucidate the substituent effect of a quinone ligand, [Ru-III(trpy)(Bu(2)SQ)(OH2)](ClO4)(2) (4CISQ = 4-chloro-1,2-benzosemiquinone) was prepared and we compared the deprotonation behavior of the. aqua ligand with that of [Ru-III(trpy)(Bu(2)SQ)(OH2)](ClO4)(2). Deprotonation of the aqua ligand of [Ru-III(trpy)(4CISQ)(OH2)](ClO4)(2) induced intramolecular electron transfer from OH- to the [Ru-III-(4CISQ)] moiety affording [Ru-II(trpy)(4CISQ)(OH.)](+), which then probably changed to [Ru-II(trpy)(4CISQ)O.-]. The antiferromagnetic interactions. (J values) between Ru-II-semiquinone and the oxyl radical for [Ru-II(trpy)(Bu(2)SQ)O.-] and for [Ru-II(trpy)(4CISQ)O.-] were 2J = -0.67 cm(-1) and -1.97 cm(-1), respectively.

DOI： 10.1021/ja0211510

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Ruthenium-quinone complex containing an aqua ligand, [Ru-II(trpy)(35tBu(2)Q)(OH2)](ClO4)(2) (trpy=2,2':6',2"-terpyridine, 35tBu(2)Q=3,5-di-tert-butyl-1,2-benzoquinone) underwent deprotonation of an aqua ligand accompanied with intramolecular electron transfer from O2- ligand to quinone ligand generating O.- ligand.

DOI： 10.1246/cl.2002.868

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Oxygenation of sulfur in ruthenium-dithiolene complex took place in CH3OH/H2O in the air and the novel diruthenium disulfinate complex formed. The similar oxygenation by use of O-18(2) and H-2 O-18 revealed that four of the eight oxygen of disulfinate complex resulted from O-2 and the remaining four came from H2O.

DOI： 10.1246/cl.2002.634

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The reaction of [Ru(bpy)(2)(napy-kappa N-2,N')](PF6)(2) [1](PF6)(2) (napy = 1,8-naphthyridine) with propiolic acid yielded a Ru-carbene complex with a five-membered metallacycle involving a 1,8-naphthylidine framework.

DOI： 10.1039/b101045j

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Doctoral thesis  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Walter de Gruyter GmbH  

cis- and trans-(R3Ge)2Pt(PMe2Ph)2 complexes as key intermediates of bis-germylation of alkynes have been prepared, and their structures have been established by spectroscopic methods and X-ray crystallography. The cis isomers afford digermanes, (R3Ge)2 as reductive elimination products in good yields. In contrast, the trans isomers lead to monogermanes.

DOI： 10.1515/MGMC.2001.24.9.647

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Hexamethyldigermane, Me3CeGeMe3, reacted with various alkynes in the presence of platinum complexes at 120 degreesC to afford Z-1,2-bis(germyl)ethenes in moderate to good yields. Terminal alkynes exhibit higher reactivities than internal ones. [Pt(acac)(2)] and [Pt(dba)(2)] serve as efficient catalysts, while [Pt(PPh3)(4)], [PtCl2(PPh3)(2)], and [Pt(dba)(2)]-phosphite were found to be inactive. Four- and six-membered cyclic oligogermanes, such as dodecamethylcyclohexagermane. (Me2Ge)(6), reacted with alkynes in the presence of platinum catalysts to yield 1,4-digermacyclohexa-2,5-dienes in ca. 30% yield. The reactions of phenylacetylene with 1,2-digermacyclohexa-3,5-dienes afforded the corresponding 1,4-digermacyclohexa-2,5,7-trienes in 93% yield. Bis(germyl)platinum complexes having various tertiary phosphine ligands have been prepared as models of a key intermediate in the above mentioned catalytic bis-germylation of alkynes, and their structures have been established by spectroscopic methods and X-ray crystallography. Bis(germyl)platinum complexes reacted with phenylacetylene to give the corresponding insertion products, germyl(germylvinyl)platinum species, whose structures have been determined by spectroscopic and X-ray analysis. Germyl(germylvinyl)platinum complexes were found to liberate a bis-germylation product of the alkyne upon heating. The result supports a mechanism involving the oxidative addition of a digermane to a Pt(0) complex, the insertion of an alkyne into one of the two Pt-Ge bonds to give a germyl(germylvinyl)platinum species, and the reductive elimination of the bis-germylation product of the alkyne. Evidence suggesting the extrusion of a germylene unit from the bis-germylplatinum species has been obtained, accounting for the generation courses of other by-products.

DOI： 10.1246/bcsj.74.123

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The novel bridging ligand 1,8-bis(2,2':6',2"-terpyridyl)anthracene (btpyan) is synthesized by three reactions from 1,8-diformylanthracene to connect two [Ru(L)(OH)](+) units (L = 3,6-di-tert-butyl-1,2;benzoquinone (3,6-Bu-t(2)-qui) and 2,2'-bipyridine (bpy)). An addition of (BuOK)-Bu-t (2.0 equiv) to a methanolic solution of [Ru-2(II)(OH)(2)(3,6-(t)Bu(2)qui)(2)(btpyan)](SbF6)(2) ([1](SbF6)(2)) results in the generation of [Ru-2(II)(O)(2)(3,6-(t)Bu(2)sq)(2)(btpyan)](0) (3,6-(t)Bu(2)sq = 3,6 -di-tert-butyl-1,2-semiquinone) due to the reduction of quinone coupled with the dissociation of the hydroxo protons. The resultant complex [Ru-2(II)(O)(2)(3,6-(t)Bu(2)sq)(2)(btpyan)](0) undergoes ligand-localized oxidation at E-1/2 = +0.40 V (vs Ag/AgCl) to give [Ru-2(II)(O)(2)(3,6-(t)Bu(2)qui)(2)(btpyan)](2+) in MeOH solution: Furthermore, metal-localized oxidation of [Ru-2(II)(O)(2)(3, 6-(t)Bu(2)qui)(2)(btpyan)](2+) at E-p = + 1.2 V in CF3CH2OH/etheq or water gives [Ru-2(III)(O)(2)(3,6-(t)Bu(2)qui)(2)(btpyan)](4+), which catalyzes water oxidation. Controlled-potential electrolysis of [1](SbF6)(2) at +1.70 V in the presence of H2O in CF3CH2OH evolves dioxygen with a current efficiency of 91% (21 turnovers). The turnover number of O-2 evolution increases to 33 500 when the electrolysis is conducted in water (pH 4.0) by using a [1](SbF6)(2)-modified ITO electrode. On the other hand, the analogous complex [Ru-2(II)(OH)(2)(bpy)(2)(btpyan)](SbF6)(2) ([2](SbF6)(2)) shows neither dissociation of the hydroxo protons, even in the presence of a large excess of (BuOK)-Bu-t, nor activity for the oxidation of H2O under similar conditions.

DOI： 10.1021/ic000552i

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Deprotonation and two-electron oxidation of [Ru-2(II)(OH)(2)(Q)(2)(btpyan)](2+) (Q = 3,6-di(tert-butyl)-1,2-quinone, btpyan = 1,8-bis(2,2':6',2"-terpyridyl)anthracene) was converted to bis(ruthenium-oxo) complex [Ru-2(II)(O)(2)(Q)(2)(btpyan)](2+), which oxidized 1,3-cychrohexadiene and 1,2-dihydronaphtalene to corresponding aromatic compounds in the presence of AgClO4 and t-BuOK. On the other hand, mononuclear complex [Ru-II(OH2)(Q)(Ph-terpy)](2+) (Ph-terpy = 4'-phenyl-2,2': 6',2"-terpyridine, [2](2+)) was converted to [Ru-II(OH)(Q)(Ph-terpy)](2+) under the similar conditions, but displayed the low activity for the oxidation compared with the dinuclear complex [1](2+).

DOI： 10.1246/cl.2000.910

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Electrochem. oxidn. of water is catalyzed by an ITO electrode modified with a bis(ruthenium-hydroxo) complex. This ruthenium complex is prepd. by reacting RuCl3 with 1,8-bis(terpyridyl)anthracene (btpyan) in MeOH, treating [Ru2Cl6(btpyan)] with 3,6-di-tert-butyl-1,2-benzenediol in the presence of KOAc in MeOH. This [RuII 2(OAc)(3,6-tBu2sq)2(btpyan)]+ (3,6-tBu2sq = 3,6-di(tert-butyl)-1,2-semiquinone) was treated with triflic acid in MeOH contg. water and then sodium hexafluoroantimonate to give [Ru2(OH)2(3,6-tBu2qui)2(btpyan)](SbF6)2. When a controlled-potential electrolysis for this complex on ITO electrode was conducted at +1.7 V (vs. Ag/AgCl) in water, 1.1 mL of O2 evolved after 20.2 C had passed in the electrolysis. The current efficiency for O2 evolution was 95%.

DOI： 10.1002/(SICI)1521-3773(20000417)39:8<1479::AID-ANIE1479>3.0.CO;2-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

1, 1, 2, 2-Tetraalkyl-3, 6-diphenyl-1, 2-digermacyclohexa-3, 5-dienes (1) reacted with iron pentacarbonyl to give the corresponding tricarbonyl(eta(4)-1,1,2,2-tetraalkyl-3,6-diphenyl-1,2-digermacyclohexa-3,5-diene)iron (2). Heating 2 caused extrusion of dialkylgermylenes to give (eta(4)-1,1-dialkyl-2,5-diphenyl-1-germacyclopenta-2,4-diene)tricarbonyliron (3). The structures of the (diene)iron tricarbonyls were determined by X-ray crystal structure analysis.

DOI： 10.1246/cl.1998.991

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