- Electrochemistry and ion-sensing properties of calix[4]arene derivatives
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The cyclic voltammetric properties of several substituted calix[4]arenes were examined in acetonitrile and dichloromethane. The compounds that contained one phenolic group in the macrocyclic cavity were able to be electrochemically oxidised at positive potentials. In acetonitrile, cyclic voltammetry experiments indicated that the phenolic compounds were oxidised in a two-electron (one-proton) process over all measured scan rates (up to 50 V s-1), while in dichloromethane, the oxidation process occurred by one-electron at scan rates ≥5 V s-1, to most likely form the radical cations. In both solvents, longer timescale (minutes to hours) controlled potential coulometry experiments indicated that the oxidation process occurred by two-electrons per molecule, to form reactive diamagnetic cations that could not be reduced back to the starting materials under electrolysis conditions. The ion-sensing properties of the compounds were investigated in polymer membrane ion-selective electrodes and it was found that they responded reversibly in a Nernstian fashion to Groups 1 and 2 metals and had the highest selectivity to the cesium cation.
- Chen, Shanshan,Webster, Richard D.,Talotta, Carmen,Troisi, Francesco,Gaeta, Carmine,Neri, Placido
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- Competing hydrogen-bonding, decomposition, and reversible dimerization mechanisms during the one- and two-electron electrochemical reduction of retinal (Vitamin A)
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Retinal (R) can be sequentially voltammetrically reduced in CH 3CN in two one-electron processes to form first the anion radical (Ra?￠-) at -1.75 (?±0.04) V vs Fc/Fc+ (Fc = ferrocene) then the dianion (R2-) at -
- Tan, Ying Shan,Yue, Yanni,Webster, Richard D.
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- METAL COMPLEXES WITH TETRAPYRROLE LIGANDS. 50. REDOX POTENTIALS OF SANDWICHLIKE METAL BIS(OCTAETHYLPORPHYRINATES) AND THEIR CORRELATION WITH RING-RING DISTANCES
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On the basis of prior work describing the synthesis and structure of sandwichlike metal bis(porphyrinates) M(OEP)2 (I:M=Y, La, ..., Lu, except Pm), the electron-transfer reactions of these double-deckers are presented.Apart from the CeIV complex Ce(OEP)2 (1c), all the other species contain MIII ions that are not affected in the redox reactions.The neutral MIII complexes 1 are porphyrin ?-radicals yielding the porphyrin ?-diradical cations + (2) upon reversible one-electron oxidation and the monoanions - (3) or the porphyrin ?-radical dianions 2- (4) upon reversible one- or two-electron reduction.Ce(OEP)2 (1c) is reversibly oxidized to the porphyrin ?-radical cation + (2c).The quasi-reversible reduction of (1c) gives the anion - (3c) with CeIII.For the neutral MIII complexes 1, the energies of the near-infrared absorption bands and the redox potentials for the processes 12 are correlated with the ionic radii rI. of the tervalent central ions MIII.A decrease of the ring oxidation potentials parallels a decrease of the ionic radii and, hence, the ring-ring distances in the double-deckers.
- Buchler, Johann W.,Scharbert, Bernd
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- Electrochemical/chemical oxidation of bisphenol A in a four-electron/two- proton process in aprotic organic solvents
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The electrochemical behavior of bisphenol A (BPA) was examined using cyclic voltammetry, bulk electrolysis and chemical oxidation in aprotic organic solvents. It was found that BPA undergoes a chemically irreversible voltammetric oxidation process to form compounds that cannot be electrochemically converted back to the starting materials on the voltammetric timescale. To overcome the effects of electrode fouling during controlled potential electrolysis experiments, NO+ was used as a one-electron chemical oxidant. A new product, hydroxylated bisdienone was isolated from the chemical oxidation of BPA with 4 mol equiv of NO+SbF6- in low water content CH3CN. The structure of the cation intermediate species was deduced and it was proposed that BPA is oxidized in a four-electron/two-proton process to form a relatively unstable dication which reacts quickly in the presence of water in acetonitrile (in a mechanism that is similar to phenols in general). However, as the water content of the solvent increased it was found that the chemical oxidation mechanism produced a nitration product in high yield. The findings from this study provide useful insights into the reactions that can occur during oxidative metabolism of BPA and highlight the possibility of the role of a bisdienone cation as a reactive metabolite in biological systems.
- Chan, Ya Yun,Yue, Yanni,Li, Yongxin,Webster, Richard D.
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- Phenylcyanamidoruthenium scorpionate complexes
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Nine [Ru(Tp)(dppe)L] complexes, where Tp is hydrotris(pyrazol-1-yl)borate, dppe is ethylenebis(diphenylphosphine), and L is (4-nitrophenyl)cyanamide (NO2pcyd-), (2-chlorophenyl)cyanamide (2-Clpcyd -), (3-chlorophenyl)cyanamide (3-Clpcyd-), (2,4-dichlorophenyl)cyanamide (2,4-Cl2pcyd-), (2,3-dichlorophenyl)cyanamide (2,3-Cl2pcyd-), (2,5-dichlorophenyl)cyanamide (2,5-Cl2pcyd-), (2,4,5-trichlorophenyl)cyanamide (2,4,5-Cl3pcyd-), (2,3,5,6-tetrachlorophenyl)cyanamide (2,3,5,6-Cl4pcyd-), and (pentachlorophenyl)cyanamide (Cl5pcyd-), and the dinuclear complex [{Ru(Tp)(dppe)}2(μ-adpc)], where adpc 2- is azo-4,4-diphenylcyanamide, have been prepared and characterized. The crystal structures of [Ru(Tp)(dppe)(Cl5pcyd)] and [{Ru(Tp)(dppe)}2(μ-adpc)] reveal the RuII ion to occupy a pseudooctahedral coordination sphere in which the cyanamide ligand coordinates to RuII by its terminal nitrogen atom. For both complexes, the cyanamide ligands are planar, indicating significant π mixing between the cyanamide and phenyl moieties as well as the azo group in the case of adpc2-. The optical spectra of the nominally ruthenium(III) species [Ru(Tp)(dppe)L]+ were obtained through spectroelectrochemistry measurements and showed an intense near-IR absorption band. Time-dependent density functional theory calculations of these species revealed that oxidation of the ruthenium(II) species led to species where partial oxidation of the cyanamide ligand had occurred, indicative of noninnocent character for these ligands. The spin densities reveal that while the 3-Clpycd species has substantial RuII(3-Clpycd0) character, the Cl5pycd species is a much more localized ruthenium(III) complex of the Cl5pycd monoanion. Some bond order and charge distribution data are derived for these ruthenium(III) species. The near-IR band is assigned as a quite complex mixture of d-d, 4dπ to L(NCN) MLCT, and L(NCN) to Ru 4d LMCT with even a scorpionate ligand component. Spectroelectrochemistry was also performed on [{Ru(Tp)(dppe)} 2(μ-adpc)] to generate the mixed-valence state. The intense intervalence transition that is observed in the near-IR is very similar to that previously reported for [{Ru(trpy)(bpy)}2(μ-adpc)]2+, where trpy is 2,2′:6′,2″-terpyridine and bpy is 2,2′-bipyridine, and by analogy identifies [{Ru(Tp)(dppe)} 2(μ-adpc)]+ as a delocalized mixed-valence complex.
- Harb, Carmen,Kravtsov, Pavel,Choudhuri, Mohommad,Sirianni, Eric R.,Yap, Glenn P.A.,Lever,Crutchley, Robert J.
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- PGSE NMR diffusion overhauser studies on [Ru(Cp*)(η6- arene)][PF6], plus a variety of transition-metal, inorganic, and organic salts: An overview of ion pairing in dichloromethane
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PGSE diffusion, 1F, 1H HOESY and 13CNMR studies for a series of [Ru(Cp*)(η6-arene)][PF6] (1) salts are presented. The solid-state structure of [Ru(Cp*) (η6-fluorobenzene)][PF6] (1c) is reported. The extent of the ion pairing and the relative positions of the ions are shown to depend on the arene. For the solvent dichloromethane, new and literature PGSE data for PF6- salts of transition-metal, inorganic, and organic salts are compared. Taken together, these new results show that the charge distribution and the ability of the anion to approach the positively charged positions (steric effects due to molecular shape) are the determining factors in deciding the amount of ion pairing. DFT calculations of the charges in four salts of type 1, as well as in a variety of other salts, using a natural population analysis (NPA), support this view. This represents the first attempt, using experimental data, to understand, correlate, and partially explain the various degrees of ion pairing in a widely different collection of salts.
- Moreno, Aitor,Pregosin, Paul S.,Veiros, Luis F.,Albinati, Alberto,Rizzato, Silvia
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- Thermal stability of quaternary ammonium hexafluorophosphates and halides
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Thermal decomposition of hexafluorophosphates of short-chain tetraalkylammonium salts of the general formula R3R'NPF6, where R3 = R' = CH3, C2H5, C 4H9; R3 = C2H5, R' = CH2C6H6 or CH2CH=CH2, was studied by thermal gravimetric analysis. Measurements were performed in air in the temperature interval 20-500°N. The thermal stability of halides with the same cations in the same temperature interval was studied for comparison. The effect of cation on the thermal stability of the halides and hexafluorophosphates was examined. The mechanism of thermal decomposition of quaternary ammonium hexafluorophosphates was suggested.
- Zhuravlev,Nikol'skii,Voronchikhina
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- Tetracyanido(difluorido)phosphates M+[PF2(CN)4]-
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The systematic study of the reaction of M[PF6] salts and Me3SiCN led to a synthetic method for the synthesis and isolation of a series of salts containing the unprecedented [PF2(CN)4]- ion in good yields. The reaction temperature, pressure, and stoichiometry were optimized. The crystal structures of M[PF2(CN)4] (M=[nBu4N]+, Ag+, K+, Li+, H5O2+) were determined. X-ray crystallography showed the exclusive formation of the cis isomer in accord with 31P and 19F solution NMR spectroscopy data. Starting with the K[PF2(CN)4] the room temperature ionic liquid EMIm[PF2(CN)4] was prepared exhibiting a rather low viscosity.
- Bresien, Jonas,Ellinger, Stefan,Harloff, J?rg,Schulz, Axel,Sievert, Katharina,Stoffers, Alrik,T?schler, Christoph,Villinger, Alexander,Zur T?schler, Cornelia
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- Deoxygenative Fluorination of Phosphine Oxides: A General Route to Fluorinated Organophosphorus(V) Compounds and Beyond
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Fluorinated organophosphorus(V) compounds are a very versatile class of compounds, but the synthetic methods available to make them bear the disadvantages of 1) occasional handling of toxic or pyrophoric PIII starting materials and 2) a dependence on hazardous fluorinating reagents such as XeF2. Herein, we present a simple solution and introduce a deoxygenative fluorination (DOF) approach that utilizes easy-to-handle phosphine oxides as starting materials and effectively replaces harsh fluorinating reagents by a combination of oxalyl chloride and potassium fluoride. The reaction has proven to be general, as R3PF2, R2PF3, and RPF4 compounds (as well as various cations and anions derived from these) are accessible in good yields and on up to a multi-gram scale. DFT calculations were used to bolster our observations. Notably, the discovery of this new method led to a convenient synthesis of 1) new difluorophosphonium ions, 2) hexafluorophosphate salts, and 3) fluorinated antimony- and arsenic- compounds.
- Bornemann, Dustin,Brüning, Fabian,Grützmacher, Hansj?rg,Guan, Liangyu,Küng, Sebastian,Pitts, Cody Ross,Togni, Antonio,Trapp, Nils,Wettstein, Lionel
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supporting information
p. 22790 - 22795
(2020/10/06)
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- Gold(I) Complexes Nuclearity in Constrained Ferrocenyl Diphosphines: Dramatic Effect in Gold-Catalyzed Enyne Cycloisomerization
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Di-tert-butylated-bis(phosphino)ferrocene ligands bearing phosphino substituents R (R=phenyl, cyclohexyl, iso-propyl, mesityl, or furyl) allow tuning the selective formation of Au(I) halide complexes. Thus, dinuclear linear two-coordinate, but also rare mononuclear trigonal three-coordinate and tetrahedral four-coordinate complexes were formed upon tuning of the conditions. Both Au(I) chloride and rarer Au(I) iodide complexes were synthesized, and their X-ray diffraction analysis are reported. The significance of the control of structure and nuclearity in Au(I) complexes is further illustrated herein by its strong effect on the efficiency and selectivity of gold-catalysed cycloisomerization. Cationic linear digold(I) bis(dicyclohexylphosphino) ferrocenes outperform other catalysts in the demanding regioselective cycloisomerization of enyne sulphonamides into cyclohexadienes. Conversely, tetrahedral and trigonal cationic monogold(I) complexes were found incompetent for enyne cycloaddition. We used the two-coordinate linear electron-rich Au(I) complex 2 b (R=Cy) to extend the scope of selective intramolecular cycloaddition of different 1,6-enyne sulfonylamines with high activity and excellent selectivity to the endo cyclohexadiene products.
- Nguyen, Tuan-Anh,Roger, Julien,Nasrallah, Houssein,Rampazzi, Vincent,Fournier, Sophie,Cattey, Hélène,Sosa Carrizo, E. Daiann,Fleurat-Lessard, Paul,Devillers, Charles H.,Pirio, Nadine,Lucas, Dominique,Hierso, Jean-Cyrille
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supporting information
p. 2879 - 2885
(2020/08/13)
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- Lewis Acidity Scale of Diaryliodonium Ions toward Oxygen, Nitrogen, and Halogen Lewis Bases
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Equilibrium constants for the associations of 17 diaryliodonium salts Ar2I+X- with 11 different Lewis bases (halide ions, carboxylates, p-nitrophenolate, amines, and tris(p-anisyl)phosphine) have been investigated by titrations followed by photometric or conductometric methods as well as by isothermal titration calorimetry (ITC) in acetonitrile at 20 °C. The resulting set of equilibrium constants KI covers 6 orders of magnitude and can be expressed by the linear free-energy relationship lg KI = sI LAI + LBI, which characterizes iodonium ions by the Lewis acidity parameter LAI, as well as the iodonium-specific affinities of Lewis bases by the Lewis basicity parameter LBI and the susceptibility sI. Least squares minimization with the definition LAI = 0 for Ph2I+ and sI = 1.00 for the benzoate ion provides Lewis acidities LAI for 17 iodonium ions and Lewis basicities LBI and sI for 10 Lewis bases. The lack of a general correlation between the Lewis basicities LBI (with respect to Ar2I+) and LB (with respect to Ar2CH+) indicates that different factors control the thermodynamics of Lewis adduct formation for iodonium ions and carbenium ions. Analysis of temperature-dependent equilibrium measurements as well as ITC experiments reveal a large entropic contribution to the observed Gibbs reaction energies for the Lewis adduct formations from iodonium ions and Lewis bases originating from solvation effects. The kinetics of the benzoate transfer from the bis(4-dimethylamino)-substituted benzhydryl benzoate Ar2CH-OBz to the phenyl(perfluorophenyl)iodonium ion was found to follow a first-order rate law. The first-order rate constant kobs was not affected by the concentration of Ph(C6F5)I+ indicating that the benzoate release from Ar2CH-OBz proceeds via an unassisted SN1-type mechanism followed by interception of the released benzoate ions by Ph(C6F5)I+ ions.
- Legault, Claude Y.,Mayer, Robert J.,Mayr, Herbert,Ofial, Armin R.
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supporting information
(2020/03/13)
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- Lewis Acid Catalyzed Synthesis of Cyanidophosphates
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Salts containing new cyanido(fluorido)phosphate anions of the general formula [PF6-n(CN)n]- (n=1-4) were synthesized by a very mild Lewis-acid-catalyzed synthetic protocol and fully characterized. All [PF6-n(CN)n]- (n=1-4) salts could be isolated on a preparative scale. It was also possible to detect the [PF(CN)5]- but not the [P(CN)6]- anion. The best results with respect to purity, yield, and low cost were obtained when the F-/CN- substitution reactions were carried out in ionic liquids. Cyanido(fluorido)phosphates: Salts containing [PF6-n(CN)n]- (n=1-4) ions were isolated on a preparative scale by utilizing Lewis acids (LA) catalysts under mild conditions (see equation). The best results with respect to purity, yield, and low cost were obtained when the F-/CN- substitution reactions were carried out in ionic liquids.
- Bl?sing, Kevin,Ellinger, Stefan,Harloff, J?rg,Schulz, Axel,Sievert, Katharina,T?schler, Christoph,Villinger, Alexander,Zurt?schler, Cornelia
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supporting information
p. 4175 - 4188
(2016/03/16)
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- FLUORO AND CHLORO CYANO COMPOUNDS OF THE 15TH GROUP
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The invention discloses certain fluoro and chloro cyano compounds of the 15th group of the periodic table with 1 to 5 cyano residues, represented by formula (I), by a reaction using trimethylsilylcyanide, a method for their preparation; the compounds are used as ionic liquids; [Catn+] [(Z1(Q1)6-m(CN)m)- ]n (I) Catn+ is a cation, Z1 is P, As, Sb or Bi, Q1 is fluoro or chloro, m is 1, 2, 3 or 5 and n is 1, 2, 3 or 4.
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Page/Page column 48; 49
(2014/10/29)
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- Ion exchange synthesis and thermal characteristics of some [N +4444] based ionic liquids
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Eight salts, derived from tetrabutylammonium cation [N+ 4444] and inorganic anions like BF4-, NO 3-, NO2-, SCN-, BrO 3-, IO3-, PF6- and HCO3- were synthesized using the ion exchange method. These ionic liquids (ILs) were characterized using thermogravimetry, differential scanning calorimetry and infrared spectroscopy. Thermophysical properties such as density, volume expansion, heat of fusion, heat of solid-solid transitions, specific heat capacity and thermal energy storage capacity were determined. The total of heat of solid-solid transitions observed below the melting points exceeded the heat of fusion in some cases. The thermal conductivity of the samples was determined both in solid and liquid phases. High values of thermal energy storage capacity and handsome liquid phase thermal conductivities made many of the ionic liquids under investigation were recommended as Thermal Energy Storage Devices (TESDs) as well as heat transfer fluids.
- Bhatt, Vasishta D.,Gohil, Kuldip
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- Efficient method for varying the anions in quaternary onium halides
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Quaternary onium salts of halides can be efficiently converted into the corresponding quaternary onium salts of various anions [NO3 -, BF4-, PF6-, CF 3SO3-, CH3SO3 -, ClO4-, p-CH3C6H 4SO3-, CF3CO2 -, 2,4-(NO2)2C6H3O -] by treating the onium halide with trimethyl phosphate under neat condition in the presence of an equivalent amount of conjugate acid of the desired anion.
- Jeon, Jong Yeob,Varghese, Jobi Kodiyan,Park, Ji Hae,Lee, Suck-Hyun,Lee, Bun Yeoul
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experimental part
p. 3566 - 3569
(2012/08/14)
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- PROCESS FOR ABSORBING METHYLACROLEIN WITH IONIC LIQUID
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Disclosed is a process for absorbing methylacrolein, characterized in that it absorbs methylacrolein by an absorbent comprising an ionic liquid. The absorbent can absorb methylacrolein effectively, and it is easy to be separated from methylacrolein, regenerated and recycled. It is a green absorbent. The technique is a green methylacrolein absorbing and separating technique.
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Page/Page column 3
(2011/02/18)
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- Synthesis, characterization, and surface studies of conjugated polymers possessing 2,2'-biimidazole moieties
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Two novel 2,2'-biimidazole-thiophene structures, 5,5'-bis(2,2'-bithiophene- 5-yl)-1,1'-dimethyl-2,2'-biimidazole and 5,5'-bis(3,4-ethylenedioxythiophene-2- yl)-1,1'-dimethyl-2,2'-biimidazole, have been synthesized and electrochemically polymerized. These materials underwent facile oxidation on Pt and ITO surfaces in CH2Cl2/Bu4NPF6 to yield conjugated, electroactive polymer films. The films were characterized with cyclic voltammetry, electronic absorption spectroscopy, and atomic force microscopy.
- Walker,Douglas,Mac Lean
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body text
p. 729 - 737
(2009/12/04)
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- Interaction between methanol and the Cl-, Br-, I-, NO3-, ClO4-, BF4-, SO3CF3- and PF6- anions studied by FTIR spectroscopy
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The interaction between methanol and the Cl-, Br-, I-, NO3-, ClO4-, BF4-, SO3CF3- and PF6- anions in dilute dichloromethane solutions has been investigated. The OH stretching vibration was used to monitor the hydrogen bonds formed between the anions and the methanol molecules, providing a direct measure of the hydrogen-bond strength. Concentrations of free and anionbonded methanol molecules were measured and the equilibrium constants calculated. The wavenumber shift and the free energy of hydrogen-bond formation was found to be significantly correlated. For the anions studied it was found that the hydrogen-bond strength increases in the order: PF6- 4- 4- 3CF3- 3- - -. Acta Chemica Scandinavica 1997.
- Kristiansson, Olof,Schuisky, Mikael
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p. 270 - 273
(2007/10/03)
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- Cationic (η3-allyl)metal complexes part XIV. Catalytic oligomerisation of ethylene: A very selective dimerisation catalyst prepared from [(η3-methallyl)Ni(cod)]PF6 and a tris(3-sulphophenyl)-phosphine salt
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The influence of a tris(3-sulfophenyl)phosphine salt on the oligomerization of ethylene catalyzed by [(η3-methallyl)Ni(cod)]PF6 has been investigated. Introduction of this particular ligand slightly lowers the catalytic activity of the cationic nickel complex, but always results in increased selectivity for dimerization at the expense of the formation of trimers. Selectivities in butenes up to 96% could be obtained.
- Brunet,Sivade,Tkatchenko
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p. 291 - 302
(2008/10/08)
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- Effects of Quaternary Ammonium Salts on Reactions of Aromatic radical Anions Formed in Tetrahydrofuran by Pulse Radiolysis
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Pulse radiolysis of biphenyl (BP) and pyrene (Py) in tetrahydrofuran (THF) solution was carried out in the presence of various kinds of quaternary ammonium salts, such as Bu4NPF6, Bu4NBF4, Bu4NI, BzMe3NPF6 and PhMe3NPF6 (Bu, butyl; Me, mthyl; Bz, benzyl; and Ph, phenyl).The decay behaviors of the radical anions, BP-. and Py-., are significantly affected by the addition of the salts.The anions of the salts, PF6-, BF4-, and I-, are considered to form ion pairs with the solvent counterions, THF(H+), resulting in a retardation of the neutralization reactions.The rate constants for the neutralization reactions have been determined in the absence and presence of Bu4NPF6.The addition of BzMe3NPF6 (or PhMe3NPF6) accelerates the decay of BP-. and retards the decay of Py-., depending on the rates of reactions of the radical anions with BzMe3N+ (or PhMe3N+).The reactivity of BP-. in the electron transfer to Py seems to be reduced in the presence of Bu4NPF6.The effect of Bu4N+ on the reactions of the radical anions is discussed.
- Yamamoto, Yukio,Nishida, Shoichi,Yabe, Katsuyoshi,Hayashi, Koichiro,Takeda,Seishi,Tsumori, Kunihiko
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p. 2368 - 2372
(2007/10/02)
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- Ground- and Excited-State Oxidation-Reduction Chemistry of (Triphenyltin)- and (Triphenylgermanium)tricarbonyl(1,10-phenanthroline)rhenium and Related Compounds
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Optical absorptions and emission spectroscopy and the photochemistry and electrochemistry are reported for complexes of the general formula R3EM(CO)3L (R = Ph or Me; E = Ge or Sn; M = Mn or Re; L = 1,10-phenanthroline, 2,2'-bipyridine, or 2,2'-biquinoline).The lowest excited state in each system results from charge-transfer, (E-M)?b -> ?*L, absorption.Several of the Re complexes (R = Ph; E = Ge or Sn; L = 2,2'-bipyridine or 1,10-phenanthroline) exhibit optical emission from the lowest excited state at 298 K in fluid solution; emission lifetimes under such conditions for these complexes are ca. 10-6 s.These excited complexes can be quenched by both electron-donor quenchers and by electron-acceptor quenchers.Detailed quenching studies of Ph3SnRe(CO)3(phen) (phen = 1,10-phenanthroline) have been carried out, and quenching obeys Stern-Volmer kinetics.Electron donors, Q, for which E(Q+/Q) is more negative than ca.+0.2 V vs.SCE quench at an essentially diffusion-controlled rate.Electron acceptors, P+, for which E(P+/P) is more positive than ca.-0.1 V vs.SCE also quench at nearly a diffusion-controlled rate.Cyclic voltammetry of the complexes in CH3CN/0.1 M ClO4 typically shows a one-electron, reversible reduction in the -1.1 to -1.7 V vs.SCE range associated with the population of the lowest available ?* orbital principally localized on L.An irreversible oxidation current peak is observed in the range +0.5 to +0.8 V vs.SCE.The M-containing oxidation product is fac-+.Consistent with the groung state electrochemistry, quenching by reversibly electron-donor quenchers (e.g., N,N,N',N'-tetramethyl-p-phenylenediamine) results in no net photoredox reaction (Φ -3) whereas quenching by reversible electron-acceptor quenchers (e.g., N,N'-dimethyl-4,4'-bipyridinium) results in net redox chemistry to reduce the quencher and to form fac-+ from the complex.The data are consistent with primary formation of R3E. and the 16-valence electron + from cleavage of the +. formed by excited-state electron transfer.Rate of +. cleavage is similar to the dissociative E-M bond cleavage induced by the (E-M)?b -> ?*L optical excitation.
- Luong, John C.,Faltynek, Robert A.,Wrighton, Mark S.
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p. 7892 - 7900
(2007/10/02)
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