- A new coordination mode of the photometric reagent glyoxalbis(2- hydroxyanil) (H2gbha): Bis-bidentate bridging by gbha2- in the redox series {(μ-gbha)[Ru(acac)2]2}n (n = -2, -1, 0, +1, +2), including a radical-bridged diruthenium(III) and a RuIII/RuIV intermediate
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The bis-bidentate bridging function of gbha2- with N,O -/N,O- coordination was observed for the first time in the complex (μ-gbha)[RuIII(acac)2]2 (1). Density functional theory calculations of 1 yield a triplet ground state with a large (ΔE > 6000 cm-1) singlet-triplet gap. Intermolecular antiferromagnetic coupling was observed (J ≈ -5.3 cm-1) for the solid. Complex 1 undergoes two one-electron reduction and two one-electron oxidation steps; the five redox forms {(μ-gbha)[Ru(acac)2] 2}n (n = -2, -1, 0, +1, +2) were characterized by UV-vis-NIR spectroelectrochemistry (NIR = near infrared). The paramagnetic intermediates were also investigated by electron paramagnetic resonance (EPR) spectroscopy. The monoanion with a comproportionation constant Kc of 2.7 × 108 does not exhibit an NIR band for a Ru III/RuII mixed-valent situation; it is best described as a 1,4-diazabutadiene radical anion containing ligand gbha?3-, which binds two ruthenium(III) centers. A RuIII-type EPR spectrum with g1 = 2.27, g2 = 2.21, and g3 = 1.73 is observed as a result of antiferromagnetic coupling between one RuIII and the ligand radical. The EPR-active monocation (Kc = 1.7 × 106) exhibits a broad (Δν1/2 = 2600 cm -1) intervalence charge-transfer band at 1800 nm, indicating a valence-averaged (Ru3.5)2 formulation (class III) with a tendency toward class II (borderline situation).
- Kar, Sanjib,Sarkar, Biprajit,Ghumaan, Sandeep,Roy, Dipankar,Urbanos, Francisco A.,Fiedler, Jan,Sunoj, Raghavan B.,Jimenez-Aparicio, Reyes,Kaim, Wolfgang,Lahiri, Goutam Kumar
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- Reductive approach to mixed valency (n = 1-) in the Pyrazine Ligand-Bridged [(acac)2Ru(μ-L2-)Ru(acac)2]n (L2- = 2,5-pyrazine-dicarboxylate) through experiment and theory
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The diruthenium(III) complex [(acac)2Ru(μ-L 2-)Ru(acac)2] (1) with acac- = acetylacetonato = 2,4-pentanedionato and a 2,5-pyrazine-dicarboxylato bridge, L2-, has been obtained and structurally characterized as the rac (ΔΔ, ΛΛ) diastereomer. The RuIIIRuIII configuration in 1 (dRu-Ru = 6.799 A) results in a triplet ground state (μ = 2.82 μB at 300 K) with a density functional theory (DFT) calculated triplet-singlet gap of 10840 cm-1 and the metal ions as the primary spin-bearing centers (Mulliken spin densities: Ru, 1.711; L, 0.105; acac, 0.184). The paramagnetic 1 exhibits broad, upfield shifted 1H NMR signals with δ values ranging from -10 to -65 ppm and an anisotropic electron paramagnetic resonance (EPR) spectrum (〈g〉 = 2.133, g1 - g3 = Δg = 0.512), accompanied by a weak half-field signal at g = 4.420 in glassy frozen acetonitrile at 4 K. Compound 1 displays two closely spaced oxidation steps to yield labile cations. In contrast, two well separated reversible reduction steps of 1 signify appreciable electrochemical metal-metal interaction in the Ru IIRuIII mixed-valent state 1- (Kc ≈ 107). The intermediate 1- shows a weak, broad Ru II→RuIII intervalence charge transfer (IVCT) band at about 1040 nm (ε = 380 M-1 cm-1); the DFT approach for 1- yielded Mulliken spin densities of 0.460 and 0.685 for the two metal centers. The monitoring of the νC=O frequencies of the uncoordinated C=O groups of L2- in 1n by IR spectroelectrochemistry suggests valence averaging (Ru2.5Ru 2.5) in 1- on the vibrational time scale. The mixed-valent 1- displays a rhombic EPR signal (〈g〉 = 2.239 and Δg = 0.32) which reveals non-negligible contributions from the bridging ligand, reflecting a partial hole-transfer mechanism and being confirmed by the DFT-calculated spin distribution (Mulliken spin density of -0.241 for L in 1-). The major low energy electronic transitions in 1n (n = 0,-,2-) have been assigned as charge transfer processes with the support of TD-DFT analysis.
- Das, Amit,Scherer, Thomas,Maji, Somnath,Mondal, Tapan Kumar,Mobin, Shaikh M.,Urbanos, Francisco A.,Jimenez-Aparicio, Reyes,Kaim, Wolfgang,Lahiri, Goutam Kumar
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- Study of temperature dependencies of saturated vapor pressure of ruthenium(III) beta-diketonate derivatives
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Complexes of ruthenium(III) with the following beta-diketones: 2,4-pentanedione (Ru(acac)3), 1,1,1-trifluoro-2,4-pentanedione (Ru(tfac)3), 2,2,6,6-tetramethyl-3,5-heptanedione (Ru(thd) 3), 2,2,6,6-tetramethyl-4-fluoro-3,5-
- Morozova,Zherikova,Semyannikov,Trubin,Igumenov
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- Inversion of axial chirality in coordinated bis-β-diketonato ligands
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Mononuclear and dinuclear ruthenium(iii) complexes with bis-β-diketonato ligands (denoted by [Ru(acac)2(L-LH)] and [Ru(acac)2(L-L)Ru(acac)2], respectively) were synthesized, where acac, L-LH- and L-L2- denote acetylacetonato, monoprotonated and unprotonated bis-β-diketonato ligands, respectively. The following three ligands were used as the bis-β-diketonato ligand (L-L 2-): 1,2-diacetyl-1,2-dibenzoylethanato (denoted by dabe 2-), 1,2-diacetyl-1,2-bis(3-methylbutanoyl)ethanato (baet 2-) and 1,2-diacetyl-1,2-dipropanoylethanato (dpe2-). For the mononuclear and the meso-type dinuclear complexes, a pair of diastereomeric species were identified as Δ- (or Λ-) [Ru(acac)2(R- or S-L-LH)] and [Δ-Ru(acac)2(R- or S-L-L)Λ-Ru(acac) 2], respectively. The possibility of thermal inversion in coordinated L-LH- (mononuclear) or L-L2- (dinuclear) was pursued by monitoring the changes in the electronic circular dichroism or the 1H NMR spectra. No inversion occurred for the dinuclear complexes, when their chloroform solutions were kept at 50 °C for ca. 100 h. In contrast, some of the mononuclear complexes underwent the inversion of axial chirality to give an equilibrium mixture under the same conditions. The reaction followed the first-order rate law and the overall first-order rate constants (k) of [Ru(acac)2(L-LH)] were determined to be k = 0.13, 0.0048 and less than 0.001 h-1 for L-LH- = dabeH-, baetH - and dpeH-, respectively. The results suggest that the main factor determining the barrier height of the internal rotation is not the steric but the electronic properties of the carbon-carbon bond connecting the two β-diketonato moieties. The Royal Society of Chemistry 2013.
- Sato, Hisako,Mori, Yukie,Kitazawa, Takafumi,Yamagishi, Akihiko
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- Volatile β-diketonato complexes of ruthenium, palladium and platinum preparation and thermal characterization
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Ruthenium, palladium and platinum complexes of 2,2,6,6-tetramethyl-3,5-heptanedione (thd) and ruthenium tris acetylacetonate (acac) were synthetized and studied with TG, DTA, DSC and MS methods. Thermal properties of ruthenocene were also studied. The pla
- Lashdaf,Hatanpaeae,Tiitta
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- A NEW METHOD FOR SYNTHESIS OF RUTHENIUM(III) AND RUTHENIUM(II) COMPLEXES OF β-DIKETONES FROM RUTHENIUM BLUE SOLUTION
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The blue solution obtained by reducing hydrated ruthenium(III) trichloride with ethanol is used as a convenient starting material in the synthesis of several tris(Β-diketonato)ruthenium(III) and tris(Β-diketonato)ruthenate(II) complexes.The Hammett constans of the substituents on the ligand serve as a helpful guide for choosing the operating conditions.
- Endo, Akira,Shimizu, Kunio,Sato, Gen P.,Mukaida, Masao
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- Kinetics and Mechanisms of Ligand Exchange Reactions of Tris(acetylacetonato)-chromium(III), cobalt(III), ruthenium(III), and -rhodium(III) in Acetylacetone
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Tris(acetylacetonato)-cobalt(III), -chromium(III), -ruthenium(III), and -rhodium(III) undergo ligand exchange in acetylacetone(Hacac) at 85-190 deg C without decomposition of the complexes.The exchange rate is proportional to the complex concentration, and the first-order rate constant k0 decreases in the sequence Co(III) above Cr(III) above Ru(III) above Rh(III), k0/10-5 s-1 being 2.4 (93 deg C), 5.6 (117 deg C), 9.5 (158 deg C), and 2.4 (185 deg C), respectively.The activation enthalpies and entropies and deuterium isotope effect on k0 are significantly different between the Co(III) and the Cr(III), Ru(III) and Rh(III) complexes.An intermediate involving an one-ended acetylacetonate and a solvent molecule(Hacac) is concluded to be formed in the rate-determining step.The SN1 and the SN2 mechanism are assigned to the exchange reactions of the Co(III) complex and the others, respectively, for the rate-determining steps.
- Kido, Hiroaki
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- RUTHENIUM PURE QUADRUPOLE RESONANCE SPECTROSCOPY
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The unique chemistry of ruthenium and consequent potential importance of the quadrupole coupling constants and asymmetry parameters of 99Ru and 101Ru has prompted us to initiate an apparently original investigation of the pure nuclear quadrupole resonance spectroscopy of these two isotopes.A means for prediction of the expected resonance frequencies based on Mossbauer data is given and detailed circuit diagrams of a spectrometer which has been constructed primarly for ruthenium studies are presented.Preliminary searches carried out for ruthenium tris-acetylacetonate and bis-ruthenium tetroxide have so far failed to yield signals.Possible explanation for this are discussed and the value of continuing the work defended.
- Carter, J. C.,Good, M. L.
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- Comparative study of the reactivity of (Cp*RuCl)4 and (Cp*RuCl2)2 with trimethylsilyl-substituted oxodienyl ligands
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A comparative study of the chemical reactivity of the well-known precursors [Cp*RuCl]4 (1) and [Cp*RuCl2]2 (2) is established relative to the incorporation of silyl-substituted heterodienyl compounds. This study gives clear evidence of the influence of the solvents and the oxidation state of 1 versus 2 on these reactions. In THF, tetramer 1 reacts selectively with CH2CHCHCHOSiMe3 (3) to afford [Cp*Ru(η4-CH2CHCHCHOSiMe3)Cl] (4), while the reaction of dimer 2 leads to nonselective reactions with the formation of 4 and [Cp*Ruη3-CH2CHCHCHO)Cl2] (5). Compound 5 is thermodynamically more stable than 4. The reactivity of 1 and the mixture of isomers CH2C(Me)CHC(OSiMe3)Me (6a) and MeC(Me)CHC(OSiMe3)CH2 (6b) affords oxo- and pentadienyl compounds [Cp*Ru{η5-CH2C(Me)CHC-(OSiMe 3)CH2}] (7), [Cp*Ru(η5-CH 2C(Me)CHC(Me)O] (8), and [Cp*Ru{η3-exo-syn- CH2C(Me)CHC-(Me)O]Cl2] (9). The treatment of 2 with 3 in methanolic or ethanolic solutions at room temperature provided a preparative route to the corresponding (allyl)ruthenium(IV) species: 5, [Cp*Ru{η3-endo-CH(Me)CHCHOR]Cl2] [R = Me (10); R = Et (12)]; [Cp*Ru{η3-endo-CH2CHCHCH(OR) 2}Cl2] [R = Me (11); R = Et (13)]. The ratio of the species formed could change significatively depending on the ratios of reactants or reaction conditions. The acetal derivatives 10-13 are generated as the result of nucleophilic attack of the alcohols on compound 5. When zinc is used as a reducing agent in ethanol, compound 2 reacts with 3 or the mixture of 6a and 6b to give trimetallic compounds Cp*Ru[η5-CH 2C(R)CHC(R)O]2(μ2-ZnCl2) (R = H, 14; R = Me, 15), which have a ZnCl2 bridging two Cp*Ru[η5-CH2C(R)CHC(R)O] molecules through the oxygen atoms of die corresponding oxopentadienyl ligands, along with [Cp*Ru{η4-CH2C(R)CHC(R)X}Cl] [R = H, X = OEt, 17; R = Me, X = OH, 18] as minor products. 15 reacts in the presence of CDCl3 to give the oxidative addition products exo-syn-9 and [Cp*Ru{η3-endo-anti-CH2C(Me)CHC(Me)O}Cl 2] (19). All compounds have been fully characterized by 1H and 13C NMR spectroscopy, and the crystal structures of 5, 9, 12, and 15 are also described.
- Sanchez-Castro, M. Esther,Paz-Sandoval, M. Angeles
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- Charged, but found not guilty : Innocence of the suspect bridging ligands [RO(O)CNNC(O)OR]2- = L2- in [(acac) 2Ru(μ-L)Ru(acac)2]n, n = +,0,-,2-
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Neutral diastereoisomeric diruthenium(III) complexes, meso- and rac-[(acac)2Ru(μ-adc-OR)Ru(acac)2] (acac- = 2,4-pentanedionato and adc-OR2- = dialkylazodicarboxylato = [RO(O)CNNC(O)OR]2-, R = tert-butyl or isopropyl), were obtained from electron transfer reactions between Ru(acac)2(CH3CN) 2 and azodicarboxylic acid dialkyl esters (adc-OR). The meso isomer 3 with R = isopropyl was structurally characterized, revealing two deprotonated and N-N coupled carbamate functions in a reduced dianionic bridge with d N-N = 1.440(5) A. A rather short distance of 4.764 A has been determined between the two oxidized, antiferromagnetically coupled Ru III centers. The rac isomer 4 with R = isopropyl exhibited stronger antiferromagnetic coupling. While the oxidation of the neutral compounds was fully reversible only for 3 and 4, two well-separated (108 c 10) reversible one-electron reduction steps produced monoanionic intermediates 1--4- with intense (ε ≈ 3000 M-1 cm-1), broad (δv1/2 ≈ 3000 cm-1) absorptions in the near-infrared (NIR) region around 2000 nm. The absence of electron paramagnetic resonance (EPR) signals even at 4 K favors the mixed-valent formulation RuII(adc-OR 2-)RuIII with innocently behaving bridging ligands over the radical-bridged alternative RuII(adc-OR?-)Ru II, a view which is supported by the metal-centered spin as calculated by density functional theory (DFT) for the methyl ester model system. The second reduction of the complexes causes the NIR absorption to disappear completely, the EPR silent oxidized forms 3+ and 4+, calculated with asymmetrical spin distribution, do not exhibit near infrared (NIR) activity. The series of azo-bridged diruthenium complex redox systems [(acac)2Ru(μ-adc-R)Ru(acac)2]n (n = +,0,-,2-), [(bpy)2Ru(μ-adc-R)Ru(bpy)2]k (k = 4+,3+,2+,0,2-), and [(acac)2Ru(μ-dih-R)Ru(acac)2] m (m = 2+,+,0,-,2-; dih-R2- = 1,2-diiminoacylhydrazido(2-) ) is being compared in terms of electronic structure and identity of the odd-electron intermediates, revealing the dichotomy of innocent vs noninnocent behavior.
- Roy, Sayak,Sarkar, Biprajit,Imrich, Hans-Georg,Fiedler, Jan,Zalis, Stanislav,Jimenez-Aparicio, Reyes,Urbanos, Francisco A.,Mobin, Shaikh M.,Lahiri, Goutam Kumar,Kaim, Wolfgang
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- Synthesis and characterization of mixed-ligand ruthenium(III) complexes with oxalate and acetylacetonate ions
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Two mononuclear mixed-ligand ruthenium(III) complexes with oxalate dianion (ox2-) and acetylacetonate ion (2,4-pentanedionate, acac -), K2[Ru(ox)2(acac)] (1) and K[Ru(ox)(acac)2] (2), were prepared as a candidate for a building block. In fact, reaction of complex 2 with manganese(II) sulfate gave a heterometallic tetranuclear complex, TBA[MnII{(μ-ox)Ru III(acac)2}3] (5) in the presence of tetrabutylammonium (TBA) bromide. The 1H NMR, UV-Vis, selected IR and FAB mass spectral data of these complexes are presented. Both mixed-ligand ruthenium(III) complexes gave a Nernstian one-electron reduction step in 0.1 mol dm-3 Na2SO4 aqueous solution on a mercury electrode at 25°C. Comparison of observed reversible half-wave potentials with calculated values for a series of [Ru(ox)n(acac) 3-n]n- (n=0-3) complexes by using Lever's ligand electrochemical parameters is presented.
- Hoshino, Yoshimasa,Eto, Motoki,Fujino, Taku,Yukawa, Yasuhiko,Ohta, Tetsuo,Endo, Akira,Shimizu, Kunio,Sat?
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- Method for synthesizing ruthenium (III) acetylacetonate (by machine translation)
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A method for synthesizing the ruthenium (III) acetylacetonate, which comprises the following steps of: a, dissolving the hydrated ruthenium trichloride in water, reacting with the base to obtain the ruthenium salt solution; b, reacting the ruthenium salt solution with the acetyl acetonate solution; b, purifying the ruthenium salt solution and the acetyl acetonate solution under heating conditions; and obtaining the total reaction equation of the ruthenium (III) chloride solution and the chloride ion content _AOMARKENCODTX0AO_ 80 - 90% 50 ppm. In the formula, HL is a strong acid of a non-coordinating anion acac is acetyl acetonate. M is Na or K; the content of impurity chloride ions is reduced while the high yield of ruthenium (III) acetylacetonate is guaranteed, the product quality is improved, and industrial production is facilitated. (by machine translation)
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Paragraph 0011; 0025; 0033; 0035-0040; 0042-0044
(2020/09/10)
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- The metal complex, a chiral nematic liquid crystal composition and crystal (by machine translation)
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[Problem] helical twisting power (βM ) Is increased, and, compatibility with a large metal complex of a nematic liquid crystal, chiral nematic liquid crystal composition using the same, and a liquid crystal element. (1) Or formula (2) represented by the formula [a] complex. (1) Or formula (2) in the metal complex represented by formula having chirality, nematic liquid crystal compounds containing chiral nematic liquid crystal compositions. Chiral nematic liquid crystal composition is filled between a pair of liquid crystal element. (R is C1 a-20 straight chain alkyl group or an alkoxy group of straight chain C1 a-20)[Drawing] no (by machine translation)
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Paragraph 0062; 0063
(2019/03/01)
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- Organoruthenium compound for chemical vapor deposition raw material and production method for the organoruthenium compound
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The present invention is an organoruthenium compound for a chemical vapor deposition raw material, including dodecacarbonyl triruthenium represented by the following chemical formula, wherein the iron (Fe) concentration is 1 ppm or less. The DCR in the present invention can be produced by obtaining crude DCR by directly carbonylating ruthenium through allowing a ruthenium salt and carbon monoxide to react with each other and by purifying the crude DCR by a sublimation method. In the synthesis step, the concentration of Fe in the obtained crude DCR is preferably set at 10 ppm or less.
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Page/Page column 6
(2016/04/20)
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- Synthesis of ruthenium(iii) and rhodium(iii) tris-acetylacetonates and palladium(ii) bis-ketoiminate using microwave heating
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Preparation of ruthenium(iii) and rhodium(iii) tris-acetylacetonates and palladium(ii) bisketoiminate (Pd(i-acac)2) under microwave irradiation using different synthetic conditions, both in the solid-phase and in solution, was studied with precise control of parameters. In the solid-phase systems, the preparation of the target product was hindered. The efficiency of the microwave heating increased when liquid phases of the reagent mixtures were used. For Pd(i-acac)2, the highest yield was achieved under elevated temperature of the process, with the reaction time decreasing to several minutes. A laboratory procedure for the microwave synthesis of ruthenium(iii) and rhodium(iii) tris-acetylacetonates and palladium(ii) bis-ketoiminate in aqueous solutions was developed, which allowed us to obtain them in 85, 55, and 80% yields, respectively. These yields are higher than those reported in the literature, with the process becoming considerably less time consuming and laborious.
- Chimitov,Zherikova,Mikheev,Zharkova,Morozova,Igumenov,Arzhannikov,Tumm
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p. 2236 - 2242
(2013/10/01)
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- Can a meso-type dinuclear complex be chiral?: Dinuclear β-diketonato Ru(III) complexes
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Dinuclear Ru(III) complexes, [Ru(III)(acac)2(dabe)Ru(III)(acac) 2] (acacH = acetylacetone; dabeH2 = 1, 2-diacetyl-1,2-dibenzoylethane) and [Ru(III)(acac)2(tbet)Ru(III) (acac)2] (tbetH2 = 1,1,2,2-tetrabenzoylethane) were synthesized by reacting [Ru(acac)2(CH3CN) 2]PF6 with dabeH2 and tbetH2 respectively, in toluene. The X-ray structural analysis of a meso-type dinuclear Ru(III) complex, ΔΛ-[Ru(III)(acac)2(dabe)Ru(III)(acac) 2], showed that the bridging part became chiral due to the orthogonal twisting of two non-symmetrical β-diketonato moieties. To confirm this conclusion, the complex was resolved chromatographically to provide a pair of optical antipodes. Such chirality in the bridging part was not generated for [Ru(III)(acac)2(tbet)Ru(III)(acac)2], because the β-diketonato moieties in tbet2- are symmetrical.
- Sato, Hisako,Takase, Ryoichi,Mori, Yukie,Yamagishi, Akihiko
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p. 747 - 751
(2012/02/05)
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- Mixed-valent metals bridged by a radical ligand: Fact or fiction based on structure-oxidation state correlations
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Electron-rich Ru(acac)2 (acac- = 2,4-pentanedionato) binds to the π electron-deficient bis-chelate ligands L, L = 2,2′-azobispyridine (abpy) or azobis(5-chloropyrimidine) (abcp), with considerable transfer of negative charge. The compounds studied, (abpy)Ru(acac)2 (1), meso(μ-abpy)[Ru(acac)2] 2 (2), rac-(μ-abpy)[Ru(acac)2]2 (3), and (μ-abcp)[Ru(acac)2]2 (4), were calculated by DFT to assess the degree of this metal-to-ligand electron shift. The calculated and experimental structures of 2 and 3 both yield about 1.35 A for the length of the central N-N bond which suggests a monoanion character of the bridging ligand. The NBO analysis confirms this interpretation, and TD-DFT calculations reproduce the observed intense long-wavelength absorptions. While mononuclear 1 is calculated with a lower net ruthenium-to-abpy charge shift as illustrated by the computed 1.30 A for d(N-N), compound 4 with the stronger π accepting abcp bridge is calculated with a slightly lengthened N-N distance relative to that of 2. The formulation of the dinuclear systems with monoanionic bridging ligands implies an obviously valence-averaged RuIIIRu II mixed-valent state for the neutral molecules. Mixed valency in conjunction with an anion radical bridging ligand had been discussed before in the discussion of MLCT excited states of symmetrically dinuclear coordination compounds. Whereas 1 still exhibits a conventional electrochemical and spectroelectrochemical behavior with metal centered oxidation and two ligand-based one-electron reduction waves, the two one-electron oxidation and two one-electron reduction processes for each of the dinuclear compounds Ru 2.5(L?-)Ru2.5 reveal more unusual features via EPR and UV-vis-NIR spectroelectrochemistry. In spite of intense near-infrared absorptions, the EPR results show that the first reduction leads to RuII(L?-)RuII species, with an increased metal contribution for system 4?-. The second reduction to RuII(L2-)RuII causes the disappearance of the NIR band. One-electron oxidation of the Ru 2.5(L?-)Ru2.5 species produces a metal-centered spin for which the alternatives RuIII(L 0)RuII or RuIII(L?-)Ru III can be formulated. The absence of NIR bands as common for mixed-valent species with intervalence charge transfer (IVCT) absorption favors the second alternative. The second one-electron oxidation is likely to produce a dication with RuIII(L0)RuIII formulation. The usefulness and limitations of the increasingly popular structure/oxidation state correlations for complexes with noninnocent ligands is being discussed.
- Sarkar, Biprajit,Patra, Srikanta,Fiedler, Jan,Sunoj, Raghavan B.,Janardanan, Deepa,Lahiri, Goutam Kumar,Kaim, Wolfgang
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p. 3532 - 3542
(2008/09/19)
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- Multiple one-electron oxidation and reduction of trinuclear bis(2,4-pentanedionato)ruthenium complexes with substituted diquinoxalino[2,3-a:2′,3′-c]phenazine ligands
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The complexes (μ3-L1/L2)[Ru(acac)2]3, acac- = 2,4-pentanedionato, L1 = 2,3,8,9,14,15-hexachlorodiquinoxalino[2,3-a:2′,3′-c]phenazine and L2 = 2,3,8,9,14,15- hexamethyldiquinoxalino[2,3-a:2′,3′-c]phenazine, undergo stepwise one-electron oxidation involving a total of three electrons and stepwise one-electron reduction with three (L2) or four electrons (L1). All reversibly accessible states were characterized by UV-Vis-NIR spectroelectrochemistry. Oxidation leads to mixed-valent intermediates {(μ3-L)[Ru(acac)2]3}+ and {(μ3-L)[Ru(acac)2]3}2+ of which the RuIIIRuIIRuII combinations exhibit higher comproportionation constants Kc than the RuIIIRuIIIRuII states - in contrast to a previous report for the unsubstituted parent systems {(μ3-L3)[Ru(acac)2]3}+/2+, L3 = diquinoxalino[2,3-a:2′,3′-c]phenazine. No conspicuous inter-valence charge transfer absorptions were observed for the mixed-valent intermediates in the visible to near-infrared regions. The monocations and monoanions were characterized by EPR spectroscopy, revealing rhombic ruthenium(III) type signals for the former. Electron addition produces ruthenium(II) complexes of the reduced forms of the ligands L, a high resolution EPR spectrum with 14N and 35,37Cl hyperfine coupling and negligible g anisotropy was found for {(μ3-L1)[Ru(acac)2]3}-. DFT calculations of (μ3-L1)[Ru(acac)2]3 confirm several ligand-centered low-lying unoccupied MOs for reduction and several metal-based high-lying occupied MOs for electron withdrawal, resulting in low-energy metal-to-ligand charge transfer (MLCT) transitions.
- Ghumaan, Sandeep,Sarkar, Biprajit,Patil, Mahendra P.,Fiedler, Jan,Sunoj, Raghavan B.,Kaim, Wolfgang,Lahiri, Goutam Kumar
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p. 3409 - 3418
(2008/10/09)
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- Organic compound for CVD raw material and method of manufacturing metallic or metallic compound thin film using the organic compound
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The present invention provides an organic compound for CVD raw material prepared by mixing a first organometallic compound and at least one second organometallic compound, said first organometallic compound having a central metal atom and at least one ligand coordinated thereto and said second organic compound having the same central metal as that of the first organometallic compound and at least one different ligand coordinated thereto from the ligand of the first organometallic compound, wherein the first and second organometallic compounds differ in decomposition behavior. In particular, a CVD raw material having both easy handling and good adhesiveness to thin film, which have not been so far sufficiently compatible with each other, can be obtained by mixing a cyclopentadienyl complex or a derivative thereof as the first organometallic compound, and a β-diketonato compound as the second organometallic compound.
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Page/Page column 6
(2010/10/19)
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- Metal-induced reductive ring opening of 1,2,4,5-tetrazines: Three resulting coordination alternatives, including the new non-innocent 1,2- diiminohydrazido(2-) bridging ligand system
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Reaction of 3,6-diaryl-1,2,4,5-tetrazines (aryl = R = phenyl, 2-furyl or 2-thienyl) with 2 equiv of Ru(acac)2(CH3-CN)2 results in reductive tetrazine ring opening to yield diruthenium complexes [(acac)2RuIII(dih-R2-)RuIII(acac) 2] bridged by the new 1,2-diiminohydrazido(2-) (dih-R2- = HNC(R)NNC(R)NH2-) ligands. rac/meso diastereoisomers could be detected and separated for the compounds with R = phenyl and 2-thienyl, all species are diamagnetic and were characterized by 1H NMR spectroscopy. Crystal structure determination of the meso isomers with R = phenyl and 2-thienyl confirmed the 1,2-diiminohydrazido formulation through long N-N (≈1.40 A) and short C= N(H) bonds (≈1.31 A), implying two bridged ruthenium(III) centers at about 4.765 A distance with strong antiferromagnetic coupling. The complexes undergo two reversible and well-separated one-electron reduction and oxidation processes, respectively. EPR Spectroscopy of the paramagnetic intermediates with comproportionation constants Kc > 1012 and UV-vis-NIR spectroelectrochemistry were used to identify the accessible redox states as [(acac)2Ru II(dih-R2-)RuII(acac)2] 2-,[(acac)2RuII(dih-R2-)Ru III(acac)2]-,[(acac)2Ru III(dih-R2-)RuIII(acac)2], [(acac)2RuIII-(dih-R?-)Ru III(acac)2]+, and [(acac)2Ru III(dih-R)RuIII(acac)2]2+. While the UV-vis-NIR spectroscopic response of [(acac)2Ru(dih-R)Ru(acac) 2]0/-/2- is very similar to that of [(bpy) 2Ru(adc-R)Ru(bpy)2]4+/3+/2+, adc-R2- = 1,2-diacylhydrazido(2-), the EPR result indicating ligand-centered spin for [(acac)2RuII(dih-R?-)Ru II(acac)2]- despite deceptive NIR absorptions around 1400 nm reveals distinct differences in the electronic structures.
- Maji, Somnath,Sarkar, Biprajit,Patra, Srikanta,Fiedler, Jan,Mobin, Shaikh M.,Puranik, Vedavati G.,Kaim, Wolfgang,Lahiri, Goutam Kumar
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p. 1316 - 1325
(2008/10/09)
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- 2,4,6-Tris(2-pyridyl)-1,3,5-triazine (tptz)-derived [RuII(tptz) (acac)(CH3CN)]+ and mixed-valent [(acac) 2RuIII{(μ-tptz-H+)-}Ru II(acac)(CH3CN)]+
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Mononuclear [RuII(tptz)(acac)(CH3CN)]ClO4 ([1]ClO4) and mixed-valent dinuclear [(acac)2Ru III{(μ-tptz-H+)-}RuII(acac) (CH3CN)]ClO4 ([5]ClO4; acac = acetylacetonate) complexes have been synthesized via the reactions of RuII(acac) 2(CH3CN)2 and 2,4,6-tris(2-pyridyl)-1,3,5- triazine (tptz), in 1:1 and 2:1 molar ratios, respectively. In [1]ClO 4, tptz binds with the RuII ion in a tridentate N,N,N mode (motif A), whereas in [5]ClO4, tptz bridges the metal ions unsymmetrically via the tridentate neutral N,N,N mode with the RuII center and cyclometalated N,C- state with the RuIII site (motif F). The activation of the coordinated nitrile function in [1]ClO 4 and [5]ClO4 in the presence of ethanol and alkylamine leads to the formation of iminoester ([2]ClO4 and [7]ClO4) and amidine ([4]ClO4) derivatives, respectively. Crystal structure analysis of [2]ClO4 reveals the formation of a beautiful eight-membered water cluster having a chair conformation. The cluster is H-bonded to the pendant pyridyl ring N of tptz and also with the O atom of the perchlorate ion, which, in turn, makes short (C-H- - - - -O) contacts with the neighboring molecule, leading to a H-bonding network. The redox potentials corresponding to the RuII state in both the mononuclear {[(acac)(tptz)RuII-N≡C-CH3]ClO4 ([1]ClO4) ? [(acac)(tptz)RuII-NH=C(CH 3)-OC2H5]ClO4 ([2]ClO4) > [(acac)(tptz)RuII-NH2-C6H 4(CH3)]ClO4 ([3]ClO4) > [(acac)(tptz)RuII-NH=C(CH3)-NHC2H 5]ClO4 ([4]ClO4)} and dinuclear {[(acac) 2RuIII{(μ-tptz-H+)-}Ru II(acac)(N≡C-CH3)]ClO4 ([5]ClO 4), [(acac)2RuIII{(μ-tptz-H +(N+-O-)2)-}Ru II(acac)(N≡C-CH3)]ClO4 ([6]ClO 4), [(acac)2RuIII{(μ-tptz-H +)-}RuII(acac)(NH=C(CH3)-OC 2H5)]ClO4 ([7]ClO4), and [(acac)2RuIII{(μ-tptz-H+) -}RuII(acac)(NC4H4N)]ClO 4 ([8]ClO4)} complexes vary systematically depending on the electronic nature of the coordinated sixth ligands. However, potentials involving the RuIII center in the dinuclear complexes remain more or less invariant. The mixed-valent RuIIRuIII species ([5]ClO4-[8]ClO4) exhibits high comproportionation constant (Kc) values of 1.1 × 1012-2 × 10 9, with substantial contribution from the donor center asymmetry at the two metal sites. Complexes display RuII- and Ru III-based metal-to-ligand and ligand-to-metal charge-transfer transitions, respectively, in the visible region and ligand-based transitions in the UV region. In spite of reasonably high Kc values for [5]ClO 4-[8]ClO4, the expected intervalence charge-transfer transitions did not resolve in the typical near-IR region up to 2000 nm. The paramagnetic RuIIRuIII species ([5]ClO4-[8] ClO4) displays rhombic electron paramagnetic resonance (EPR) spectra at 77 K (〈g〉 ~ 2.15 and Δg ~ 0.5), typical of a low-spin RuIII ion in a distorted octahedral environment. The one-electron-reduced tptz complexes [RuII(tptz?-) (acac)(CH3CN)] (1) and [(acac)2RuIII{(μ- tptz-H+)?2-}RuII(acac)(CH3CN)] (5), however, show a free-radical-type EPR signal near g = 2.0 with partial metal contribution.
- Ghumaan, Sandeep,Kar, Sanjib,Mobin, Shaikh M.,Harish,Puranik, Vedavati G.,Lahiri, Goutam Kumar
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p. 2413 - 2423
(2008/10/09)
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- Sensitive oxidation state ambivalence in unsymmetrical three-center (M/Q/M) systems [(acac)2Ru(μ-Q)Ru(acac)2]n, Q = 1,10-phenanthroline-5,6-dione or 1,10-phenanthroline-5,6-diimine (n = +, 0, -, 2-)
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The new redox systems [(acac)2Ru(μ-Q1)Ru(acac) 2]n (1n) and [(acac)2Ru(μ-Q 2)Ru(acac)2]n (2n) with Q1 = 1,10-phenanthroline-5,6-dione and Q2 = 1,10-phenanthroline-5,6- diimine were studied for n = +, 0, -, and 2- using UV-Vis-NIR spectroelectrochemistry and, in part, EPR and susceptometry. The ligands can bind the first metal (left) through the phenanthroline nitrogen atoms and the second metal (right) at the o-quinonoid chelate site. The neutral compounds are already different: Compound 1 is formulated as a RuII(μ-Q 1).- RuIII species with partially coupled semiquinone and ruthenium(III) centers. In contrast, a RuIII(μ- Q2)2- RuIII structure is assigned to 2, which shows a weak antiferromagnetic spin-spin interaction (J = -1.14 cm-1) and displays an intense half-field signal in the EPR spectrum. The one-electron reduced forms are also differently formulated as RuII(μ-Q 1)2- RuIII for 1- with a Ru III-typical EPR response and as RuII(μ-Q 2).- RuII for 2- with a radical-type EPR signal at g = 2.0020. In contrast, both 12- and 22- can only be described as RuII(μ-Q)2-RuII species. The monooxidized forms 1+ and 2+ show very similar spectroscopy, including a RuIII-type EPR signal. Although no unambiguous assignment was possible here for the alternatives Ru II(μ-Q)0RuIII, RuIII(μ-Q) 2-RuIV or RuIII(μ-Q).-Ru III, the last description is favored. The reasons for identical or different oxidation state combinations are discussed.
- Ghumaan, Sandeep,Sarkar, Biprajit,Patra, Srikanta,Van Slageren, Joris,Fiedler, Jan,Kaim, Wolfgang,Lahiri, Goutam Kumar
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p. 3210 - 3214
(2008/10/09)
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- Tetrazine derived mononuclear RuII(acac)2(L) (1), [RuII(bpy)2(L)](ClO4)2 (2) and [RuII(bpy)(L)2](ClO4)2 (3) (L = 3-amino-6-(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine, acac = acetylacetonate, bpy = 2,2′-bipyridine): Syntheses, structures, spectra and redox properties
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Mononuclear ruthenium complexes of tetrazine derived L, Ru II(acac)2(L) (1), [RuII(bpy) 2(L)](ClO4)2 (2) and [RuII(bpy)(L) 2](ClO4)2 (3) (L = 3-amino-6-(3,5- dimethylpyrazol-1-yl)-1,2,4,5-tetrazine, acac = acetylacetonate and bpy = 2,2′-bipyridine) were prepared. The free L exists as a dimeric entity in the solid state via hydrogen bonding interactions involving L and water molecules present in the crystal lattice. 1 exhibits unusually strong bonds from RuII to coordinating pyrazolyl-N (2.040(2) ?) and especially to tetrazine-N (1.913(2) ?). The RuIII/RuII couples of 1-3 appeared at 0.28, 1.34 and 1.50 V versus SCE, respectively. The tetrazine and bpy-based reductions were observed at -1.33 (1); -0.55 and -1.55/-1.75/-1.98 (2); -0.47/-0.78 and -1.80/-2.02 V (3), respectively. 1, 2 and 3 displayed two MLCT bands each, corresponding to dπ(RuII) → π* (L, tetrazine) and dπ(RuII) → π* (acac or bpy or L) transitions. 1+ and 2+ showed rhombic EPR spectra at 110 and 4 K, respectively and 1-, 2- and 3 - exhibited multiple line EPR spectra at 300 K. 1-3 exhibited moderately strong emission spectra in EtOH-MeOH glass at 77 K.
- Nayak, Animesh,Patra, Srikanta,Sarkar, Biprajit,Ghumaan, Sandeep,Puranik, Vedavati G.,Kaim, Wolfgang,Lahiri, Goutam Kumar
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p. 333 - 342
(2008/10/09)
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- 3,6-Bis(2′-pyridyl)pyridazine (L) and its deprotonated form (L H +)- as ligands for {(acac)(2)Run+} or {(bpy)2Rum+}: Investigation of mixed valency in [{(acac)(2)Ru}(2)(μ-L - H+)]0 and [{(bpy)2Ru}2(μ-L - H+)]4+ by spectroelectrochemistry and EPR
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Crystallographically characterised 3,6-bis(2′-pyridyl)pyridazine (L) forms complexes with {(acac)2Ru} or {(bpy)2Ru 2+} via one pyridyl-N/pyridazyl-N chelate site in mononuclear Ru II complexes (acac)2Ru(L), 1, and [(bpy) 2Ru(L)](ClO4)2, [3](ClO4) 2. Coordination of a second metal complex fragment is accompanied by deprotonation at the pyridazyl-C5 carbon {L → (L - H +)-} to yield cyclometallated, asymmetrically bridged dinuclear complexes [(acac)2RuIII(μ-L - H +)RuIII(acac)2](ClO4), [2](ClO 4), and [(bpy)2RuII(μ-L - H +)RuII(bpy)2](ClO4)3, [4](ClO4)3. The different electronic characteristics of the co-ligands, σ donating acac- and π accepting bpy, cause a wide variation in metal redox potentials which facilitates the isolation of the diruthenium(III) form in [2](ClO4) with antiferromagnetically coupled RuIII centres (J = -11.5 cm-1) and of a luminescent diruthenium(II) species in [4](ClO4)3. The electrogenerated mixed-valent RuIIRuIII states 2 and [4]4+ with comproportionation constants Kc > 10 8 are assumed to be localised with the RuIII ion bonded via the negatively charged pyridyl-N/pyridazyl-C5 chelate site of the bridging (L - H+)- ligand. In spectroelectrochemical experiments they show similar intervalence charge transfer bands of moderate intensity around 1300 nm and comparable g anisotropies (g1 - g 3 ≈ 0.5) in the EPR spectra. However, the individual g tensor components are distinctly higher for the π acceptor ligated system 4+, signifying stabilised metal d orbitals. The Royal Society of Chemistry 2005.
- Ghumaan, Sandeep,Sarkar, Biprajit,Patra, Srikanta,Parimal, Kumar,Van Slageren, Joris,Fiedler, Jan,Kaim, Wolfgang,Lahiri, Goutam Kumar
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p. 706 - 712
(2007/10/03)
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- Isovalent and mixed-valent diruthenium complexes [(acac)2Ru (II) (μ-bpytz)Ru(II)(acac)2] and [(acac) 2Ru(II)(μ-bpytz)Ru(III)(acac) 2](CI04) (acac = acetylacetonate and bpytz = 3,6-bis(3,5-dimethylpyrazolyl)-1,2,4,5-tetrazine): Synthesis, spectroelectrochemical, and EPR investigation
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The title compounds involving the structurally characterized bridging ligand bpytz were characterized, showing very strong electrochemical stabilization of the mixed-valent RuIIRuIII state (K c = 1013.9) but no detectable (ε -1 cm-1) intervalence charge-transfer band in the infrared region. In situ reduction of the neutral precursor produces a diruthenium(II) complex of the bpytz radical anion according to EPR spectroscopy, whereas oxidation of the mixed-valent form leads to a diruthenium(III) species.
- Patra, Srikanta,Sarkar, Biprajit,Ghumaan, Sandeep,Fiedler, Jan,Kaim, Wolfgang,Lahiri, Goutam Kumar
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p. 6108 - 6113
(2008/10/09)
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- Improved synthesis and reactivity of tris(acetylacetonato)ruthenium(III)
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[Ru(acac)3] has been prepared by a new method in high yield and foundto be a precursor for the synthesis of [Ru(acac)2L2] (L = a neutral monodentate ligand viz., CH3CN, py, 3Me-py, 4Me-py, dmpzH (3,5-dimethyl pyrazole), PPh3 or AsPh3; L2 = a neutral bidentate ligand, viz., bipy(2,2'-bipyridine) or phen (1,10-phenanthroline). All the complexes are new except [Ru(acac)2(CH3CN)2] and [Ru(acac)2(PPh3)2], and are characterized by physical and electrochemical studies.
- Gupta,Poddar
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p. 457 - 460
(2007/10/03)
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- Nonadiabaticity in ruthenium(III)-titanium(III) outer-sphere electron-transfer reactions
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Ru2(OAc)4+ is reduced by Ti(III) (at 25°C, in 1 M LiCF3SO3-HCF3SO3) by a two-term rate law, indicating that both Ti3+ and TiOH2+ are effective reductants for this oxidant. Rate constants are 2.3 × 102 and 3.4 × 103 M-1 s-1, respectively. Tris(pentane-2,4-dionato)ruthenium(III) is reduced by Ti(III), in 1 M LiCl-HCl at 25°C, by the same general rate law with rate constants of 0.08 M-1 s-1 for Ti3+ and 0.7 M-1 s-1 for TiOH2+. Ti3+ is not an effective reductant for Ru(III) oxidants that lack delocalized π electrons: we take this as indicating that such reactions would be nonadiabatic.
- Earley, Joseph E.,Bose, Rathindra N.,Berrie, Barbara H.
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p. 1836 - 1839
(2008/10/08)
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