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1.
GustavoT. Ruiz MariaP. Juliarena ReynaldoO. Lezna Ezequiel Wolcan MarioR. Feliz Guillermo Ferraudi 《Helvetica chimica acta》2002,85(5):1261-1275
The photophysical and photochemical properties of (OC‐6‐33)‐(2,2′‐bipyridine‐κN1,κN1′)tricarbonyl(9,10‐dihydro‐9,10‐dioxoanthracene‐2‐carboxylato‐κO)rhenium (fac‐[ReI(aq‐2‐CO2)(2,2′‐bipy)(CO)3]) were investigated and compared to those of the free ligand 9,10‐dihydro‐9,10‐dioxoanthracene‐2‐carboxylate (=anthraquinone‐2‐carboxylate) and other carboxylato complexes containing the (2,2′‐bipyridine)tricarbonylrhenium ([Re(2,2′‐bipy)(CO)3]) moiety. Flash and steady‐state irradiations of the anthraquinone‐derived ligand (λexc 337 or 351 nm) and of its complex reveal that the photophysics of the latter is dominated by processes initiated in the Re‐to‐(2,2′‐bipyridine) charge‐transfer excited state and 2,2′‐bipyridine‐ and (anthraquinone‐2‐carboxylato)‐centered intraligand excited states. In the reductive quenching by N,N‐diethylethanamine (TEA) or 2,2′,2″‐nitrilotris[ethanol] TEOA, the reactive states are the 2,2′‐bipyridine‐centered and/or the charge‐transfer excited states. The species with a reduced anthraquinone moiety is formed by the following intramolecular electron transfer, after the redox quenching of the excited state: [ReI(aq−2−CO2)(2,2′‐bipy.)(CO)3]−⇌[ReI(aq−2−CO2.)(2,2′‐bipy)(CO)3]− The photophysics, particularly the absence of a ReI‐to‐anthraquinone charge‐transfer excited state photochemistry, is discussed in terms of the electrochemical and photochemical results. 相似文献
2.
Activating a Low Overpotential CO2 Reduction Mechanism by a Strategic Ligand Modification on a Ruthenium Polypyridyl Catalyst
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Ben A. Johnson Dr. Somnath Maji Dr. Hemlata Agarwala Dr. Travis A. White Dr. Edgar Mijangos Prof. Dr. Sascha Ott 《Angewandte Chemie (International ed. in English)》2016,55(5):1825-1829
The introduction of a simple methyl substituent on the bipyridine ligand of [Ru(tBu3tpy)(bpy)(NCCH3)]2+ (tBu3tpy=4,4′,4′′‐tri‐tert‐butyl‐2,2′:6′,2′′‐terpyridine; bpy=2,2′‐bipyridine) gives rise to a highly active electrocatalyst for the reduction of CO2 to CO. The methyl group enables CO2 binding already at the one‐electron reduced state of the complex to enter a previously not accessible catalytic cycle that operates at the potential of the first reduction. The complex turns over with a Faradaic efficiency close to unity and at an overpotential that is amongst the lowest ever reported for homogenous CO2 reduction catalysts. 相似文献
3.
Judicious Ligand Design in Ruthenium Polypyridyl CO2 Reduction Catalysts to Enhance Reactivity by Steric and Electronic Effects
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Ben A. Johnson Dr. Hemlata Agarwala Dr. Travis A. White Dr. Edgar Mijangos Prof. Dr. Somnath Maji Prof. Dr. Sascha Ott 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(42):14870-14880
A series of RuII polypyridyl complexes of the structural design [RuII(R?tpy)(NN)(CH3CN)]2+ (R?tpy=2,2′:6′,2′′‐terpyridine (R=H) or 4,4′,4′′‐tri‐tert‐butyl‐2,2′:6′,2′′‐terpyridine (R=tBu); NN=2,2′‐bipyridine with methyl substituents in various positions) have been synthesized and analyzed for their ability to function as electrocatalysts for the reduction of CO2 to CO. Detailed electrochemical analyses establish how substitutions at different ring positions of the bipyridine and terpyridine ligands can have profound electronic and, even more importantly, steric effects that determine the complexes’ reactivities. Whereas electron‐donating groups para to the heteroatoms exhibit the expected electronic effect, with an increase in turnover frequencies at increased overpotential, the introduction of a methyl group at the ortho position of NN imposes drastic steric effects. Two complexes, [RuII(tpy)(6‐mbpy)(CH3CN)]2+ (trans‐[ 3 ]2+; 6‐mbpy=6‐methyl‐2,2′‐bipyridine) and [RuII(tBu?tpy)(6‐mbpy)(CH3CN)]2+ (trans‐[ 4 ]2+), in which the methyl group of the 6‐mbpy ligand is trans to the CH3CN ligand, show electrocatalytic CO2 reduction at a previously unreactive oxidation state of the complex. This low overpotential pathway follows an ECE mechanism (electron transfer–chemical reaction–electron transfer), and is a direct result of steric interactions that facilitate CH3CN ligand dissociation, CO2 coordination, and ultimately catalytic turnover at the first reduction potential of the complexes. All experimental observations are rigorously corroborated by DFT calculations. 相似文献
4.
Electrocatalytic and Solar‐Driven CO2 Reduction to CO with a Molecular Manganese Catalyst Immobilized on Mesoporous TiO2
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Timothy E. Rosser Dr. Christopher D. Windle Dr. Erwin Reisner 《Angewandte Chemie (International ed. in English)》2016,55(26):7388-7392
Electrocatalytic CO2 reduction to CO was achieved with a novel Mn complex, fac‐[MnBr(4,4′‐bis(phosphonic acid)‐2,2′‐bipyridine)(CO)3] ( MnP ), immobilized on a mesoporous TiO2 electrode. A benchmark turnover number of 112±17 was attained with these TiO2| MnP electrodes after 2 h electrolysis. Post‐catalysis IR spectroscopy demonstrated that the molecular structure of the MnP catalyst was retained. UV/vis spectroscopy confirmed that an active Mn–Mn dimer was formed during catalysis on the TiO2 electrode, showing the dynamic formation of a catalytically active dimer on an electrode surface. Finally, we combined the light‐protected TiO2| MnP cathode with a CdS‐sensitized photoanode to enable solar‐light‐driven CO2 reduction with the light‐sensitive MnP catalyst. 相似文献
5.
Dorothy H. Gibson Mark S. Mashuta Xiaolong Yin 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(8):m366-m367
The title organometallic compound, fac‐tricarbonyl‐2κ3C‐(4,4′‐dimethyl‐2,2′‐bipyridine)‐2κ2N,N′‐triphenyl‐1κ3C1‐tin(II)rhenium(I)(Sn—Re), [ReSn(C6H5)3(C12H12N2)(CO)3], contains three unique π–π stacking interactions. The result is an infinite chain of uninterrupted alternating intra‐ and intermolecular offset π–π stacking interactions throughout the crystal lattice. This extended π–π stacking arrangement, and an additional isolated intramolecular π–π interaction between the remaining 4,4′‐dimethyl‐2,2′‐bipyridine ring and a second phenyl group, impose geometric constraints on the Re and Sn atoms, yielding distorted octahedral and tetrahedral coordinations, respectively, for the metal centers. 相似文献
6.
trans‐(Cl)‐[Ru(5,5′‐diamide‐2,2′‐bipyridine)(CO)2Cl2]: Synthesis,Structure, and Photocatalytic CO2 Reduction Activity
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Dr. Yusuke Kuramochi Kyohei Fukaya Makoto Yoshida Prof. Hitoshi Ishida 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(28):10049-10060
A series of trans‐(Cl)‐[Ru(L)(CO)2Cl2]‐type complexes, in which the ligands L are 2,2′‐bipyridyl derivatives with amide groups at the 5,5′‐positions, are synthesized. The C‐connected amide group bound to the bipyridyl ligand through the carbonyl carbon atom is twisted with respect to the bipyridyl plane, whereas the N‐connected amide group is in the plane. DFT calculations reveal that the twisted structure of the C‐connected amide group raises the level of the LUMO, which results in a negative shift of the first reduction potential (Ep) of the ruthenium complex. The catalytic abilities for CO2 reduction are evaluated in photoreactions (λ>400 nm) with the ruthenium complexes (the catalyst), [Ru(bpy)3]2+ (bpy=2,2′‐bipyridine; the photosensitizer), and 1‐benzyl‐1,4‐dihydronicotinamide (the electron donor) in CO2‐saturated N,N‐dimethylacetamide/water. The logarithm of the turnover frequency increases by shifting Ep a negative value until it reaches the reduction potential of the photosensitizer. 相似文献
7.
Dr. Hui Liu Dr. Yonggang Zhao Zhijuan Zhang Nour Nijem Prof. Dr. Yves J. Chabal Prof. Dr. Xiangfang Peng Prof. Dr. Heping Zeng Prof. Dr. Jing Li 《化学:亚洲杂志》2013,8(4):778-785
We report two new 3D structures, [Zn3(bpdc)3(2,2′‐dmbpy)] (DMF)x(H2O)y ( 1 ) and [Zn3(bpdc)3(3,3′‐dmbpy)]?(DMF)4(H2O)0.5 ( 2 ), by methyl functionalization of the pillar ligand in [Zn3(bpdc)3(bpy)] (DMF)4?(H2O) ( 3 ) (bpdc=biphenyl‐4,4′‐dicarboxylic acid; z,z′‐dmbpy=z,z′‐dimethyl‐4,4′‐bipyridine; bpy=4,4′‐bipyridine). Single‐crystal X‐ray diffraction analysis indicates that 2 is isostructural to 3 , and the power X‐ray diffraction (PXRD) study shows a very similar framework of 1 to 2 and 3 . Both 1 and 2 are 3D porous structures made of Zn3(COO)6 secondary building units (SBUs) and 2,2′‐ or 3,3′‐dmbpy as pillar ligand. Thermogravimetric analysis (TGA) and PXRD studies reveal high thermal and water stability for both compounds. Gas‐adsorption studies show that the reduction of surface area and pore volume by introducing a methyl group to the bpy ligand leads to a decrease in H2 uptake for both compounds. However, CO2 adsorption experiments with 1′ (guest‐free 1 ) indicate significant enhancement in CO2 uptake, whereas for 2′ (guest‐free 2 ) the adsorbed amount is decreased. These results suggest that there are two opposing and competitive effects brought on by methyl functionalization: the enhancement due to increased isosteric heats of CO2 adsorption (Qst), and the detraction due to the reduction of surface area and pore volume. For 1′ , the enhancement effect dominates, which leads to a significantly higher uptake of CO2 than its parent compound 3′ (guest‐free 3 ). For 2′ , the detraction effect predominates, thereby resulting in reduced CO2 uptake relative to its parent structure 3′ . IR and Raman spectroscopic studies also present evidence for strong interaction between CO2 and methyl‐functionalized π moieties. Furthermore, all compounds exhibit high separation capability for CO2 over other small gases including CH4, CO, N2, and O2. 相似文献
8.
Dr. Yann Gloaguen Christophe Rebreyend Dr. Martin Lutz Pravin Kumar Dr. Martina Huber Dr. Ir. Jarl Ivar van der Vlugt Prof. Dr. Sven Schneider Prof. Dr. Bas de Bruin 《Angewandte Chemie (International ed. in English)》2014,53(26):6814-6818
Photochemical activation of [(PNNH)Rh(N3)] (PNNH=6‐di‐(tert‐butyl)phosphinomethyl‐2,2′‐bipyridine) complex 2 produced the paramagnetic (S=1/2), [(PNN)Rh?N.‐Rh(PNN)] complex 3 (PNN?=methylene‐deprotonated PNNH), which could be crystallographically characterized. Spectroscopic investigation of 3 indicates a predominant nitridyl radical (.N2?) character, which was confirmed computationally. Complex 3 reacts selectively with CO, producing two equivalents of [(PNN)RhI(CO)] complex 4 , presumably by nitridyl radical N,N‐coupling. 相似文献
9.
Dharmalingam Sivanesan Hyung Min Kim Yoon Sungho 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(6):584-587
The title complex, [Rh(C10H15)Cl(C14H12N2O4)]Cl·2C4H5NO3, has been synthesized by a substitution reaction of the precursor [bis(2,5‐dioxopyrrolidin‐1‐yl) 2,2′‐bipyridine‐4,4′‐dicarboxylate]chlorido(pentamethylcyclopentadienyl)rhodium(III) chloride with NaOCH3. The RhIII cation is located in an RhC5N2Cl eight‐coordinated environment. In the crystal, 1‐hydroxypyrrolidine‐2,5‐dione (NHS) solvent molecules form strong hydrogen bonds with the Cl− counter‐anions in the lattice and weak hydrogen bonds with the pentamethylcyclopentadienyl (Cp*) ligands. Hydrogen bonding between the Cp* ligands, the NHS solvent molecules and the Cl− counter‐anions form links in a V‐shaped chain of RhIII complex cations along the c axis. Weak hydrogen bonds between the dimethyl 2,2′‐bipyridine‐4,4′‐dicarboxylate ligands and the Cl− counter‐anions connect the components into a supramolecular three‐dimensional network. The synthetic route to the dimethyl 2,2′‐bipyridine‐4,4′‐dicarboxylate‐containing rhodium complex from the [bis(2,5‐dioxopyrrolidin‐1‐yl) 2,2′‐bipyridine‐4,4′‐dicarboxylate]rhodium(III) precursor may be applied to link Rh catalysts to the surface of electrodes. 相似文献
10.
Yuan-Chun He Li-Yuan Xiao Zi-Han Yuan Jie Zhang Yan Wang Na Xu 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(12):1562-1568
Coordination polymers (CPs) have attracted increasing interest in recent years. In this work, two new CPs, namely poly[[aquabis(2,2′‐bipyridine‐κ2N,N′){μ3‐5‐[(4‐carboxylatophenoxy)methyl]benzene‐1,3‐dicarboxylato‐κ4O1,O1′:O3:O5}(μ‐formato‐κ3O:O,O′)dicadmium(II)] monohydrate], {[Cd2(C16H9O7)(HCO2)(C10H8N2)2(H2O)]·H2O}n ( 1 ), and poly[[(2,2′‐bipyridine‐κ2N,N′){μ3‐5‐[(4‐carboxylphenoxy)methyl]benzene‐1,3‐dicarboxylato‐κ4O1,O1′:O3:O5}manganese(II)] sesquihydrate], {[Mn(C16H10O7)(C10H8N2)]·1.5H2O}n ( 2 ), have been prepared using the tricarboxylic acid 5‐[(4‐carboxyphenoxy)methyl]benzene‐1,3‐dicarboxylic acid and 2,2′‐bipyridine under hydrothermal conditions. CP 1 displays a two‐dimensional layer structure which is further extended into a three‐dimensional (3D) supramolecular structure via intermolecular π–π interactions, while CP 2 shows a different 3D supramolecular structure extended from one‐dimensional ladder chains by intermolecular π–π interactions. In addition, the solid‐state luminescence spectra of 1 and 2 were studied at room temperature. 相似文献
11.
Chiral coordination polymers have attracted intense interest mainly due to their potential applications. Hence, two new chiral copper(II) coordination polymers {[Cu(tsgluO)(H2O)]2·3H2O}n ( 1 ) and [Cu(tsgluO)(2,2′‐bipy)]n ( 2 ) (H2tsglu?(+)‐N‐tosyl‐l‐glutamic acid; 2,2′‐bipy?2,2′‐bipyridine) were synthesized in the absence or presence of 2,2′‐bipy ligand and structurally characterized. A single crystal X‐ray diffraction study revealed that compound 1 consists of a paddle‐wheel dicopper(II) core, which links other equivalents via four tsgluO2? ligands to form a 1D double chain. Such a chain is further interconnected through weak π‐π stacking and hydrogen bonding interactions to form a 3D H‐bonded supramolecular structure with 1D channels hosting lattice water molecules. Whereas, compound 2 , containing the coordinating 2,2′‐bipy, gives rise to a ladder‐like 1D double chain. Antiferromagnetic interactions were observed in 1 and 2 . 相似文献
12.
Alexander J. Blake Pamela V. Mason Claire Wilson Neil R. Champness 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(6):m280-m282
The single‐crystal X‐ray structures of dimethyl 2,2′‐bipyridine‐6,6′‐dicarboxylate, C14H12N2O4, and the copper(I) coordination complex bis(dimethyl 2,2′‐bipyridine‐6,6′‐dicarboxylato‐κ2N,N′)copper(I) tetrafluoroborate, [Cu(C14H12N2O4)2]BF4, are reported. The uncoordinated ligand crystallizes across an inversion centre and adopts the anticipated anti pyridyl arrangement with coplanar pyridyl rings. In contrast, upon coordination of copper(I), the ligand adopts an arrangement of pyridyl donors facilitating chelating metal coordination and an increased inter‐pyridyl twisting within each ligand. The distortion of each ligand contrasts with comparable copper(I) complexes of unfunctionalized 2,2′‐bipyridine. 相似文献
13.
Cengiz Arici Filiz Ercan Raif Kurtaran Orhan Atakol 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(7):812-814
In the title compounds, {2,2′‐[2,2‐dimethyl‐1,3‐propanediylbis(nitrilomethylidyne)]diphenolato‐κ4N,N′,O,O′}nickel(II), [Ni(C19H20N2O2)], and {2,2′‐[2,2‐dimethyl‐1,3‐propanediylbis(nitrilomethylidyne)]diphenolato‐κ4N,N′,O,O′}copper(II), [Cu(C19H20N2O2)], the NiII and CuII atoms are coordinated by two iminic N and two phenolic O atoms of the N,N′‐bis(salicylidene)‐2,2‐dimethyl‐1,3‐propanediaminate (SALPD2?, C17H16N2O22?) ligand. The geometry of the coordination sphere is planar in the case of the NiII complex and distorted towards tetrahedral for the CuII complex. Both complexes have a cis configuration imposed by the chelate ligand. The dihedral angles between the N/Ni/O and N/Cu/O coordination planes are 17.20 (6) and 35.13 (7)°, respectively. 相似文献
14.
Prof. Dr. Vadapalli Chandrasekhar Puja Singh Kandasamy Gopal Alexander Steiner 《无机化学与普通化学杂志》2012,638(11):1716-1722
N,N′‐dioxide ligands such as 2, 2′‐bipyridine‐N,N‐dioxide (BPDO‐I) and 4, 4′‐bipyridine‐N,N‐dioxide (BPDO‐II) were used to trap the hydrated dimethyltin cations under controlled hydrolysis. The use of the chelating ligand BPDO‐I leads to the isolation of the discrete monocation [Me2Sn(BPDO‐I)(OH2)(NO3)]+[NO3]– ( 2 ), whereas the linear ligand BPDO‐II directs the construction of cationic polymers, [{Me2Sn(OH2)2(μ‐BPDO‐II)}2+{NO3–}2 · 2H2O]n ( 3· 2H2O) and [{Me2Sn(μ‐OH)(BPDO‐II)}22+{NO3–}2 · H2O]n ( 4· H2O) under different reaction conditions. 相似文献
15.
Yoshiko Okada Shinobu Kishi Yasuko Shishido Masako Kato 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(5):m171-m173
Dichloro(4,4′‐dipentyl‐2,2′‐bipyridine‐κ2N,N′)platinum(II), [PtCl2(C20H28N2)], adopts a discrete π–π stacking structure, where the alkyl chains are located in a random manner. In contrast, dichloro(4,4′‐diheptyl‐2,2′‐bipyridine‐κ2N,N′)platinum(II), [PtCl2(C24H36N2)], forms a layer structure comprised of alkyl chain layers and paired coordination sites, as observed for analogous complexes with longer alkyl chains. 相似文献
16.
Dr. Antonio Zucca Dr. Luca Maidich Laura Canu Dr. Giacomo L. Petretto Prof. Sergio Stoccoro Prof. Maria Agostina Cinellu Dr. Guy J. Clarkson Dr. Jonathan P. Rourke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(18):5501-5510
Rollover cyclometalation involves bidentate heterocyclic donors, unusually acting as cyclometalated ligands. The resulting products, possessing a free donor atom, react differently from the classical cyclometalated complexes. Taking advantage of a “rollover”/“retro‐rollover” reaction sequence, a succession of oxidative addition and reductive elimination in a series of platinum(II) complexes [Pt(N,C)(Me)(PR3)] resulted in a rare C(sp2)?C(sp3) bond formation to give the bidentate nitrogen ligands 3‐methyl‐2,2′‐bipyridine, 3,6‐dimethyl‐2,2′‐bipyridine, and 3‐methyl‐2‐(2′‐pyridyl)‐quinoline, which were isolated and characterized. The nature of the phosphane PR3 is essential to the outcome of the reaction. This route constitutes a new method for the activation and functionalization of C?H bond in the C(3) position of bidentate heterocyclic compounds, a position usually difficult to functionalize. 相似文献
17.
Photoinduced Energy Transfer from Poly(N‐vinylcarbazole) to Tricarbonylchloro‐(2,2′‐bipyridyl)rhenium(I)
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Dr. Engelbert Portenkirchner Dogukan Apaydin Gottfried Aufischer Dr. Marek Havlicek Prof. Matthew White Prof. Markus Clark Scharber Prof. Niyazi Serdar Sariciftci 《Chemphyschem》2014,15(16):3634-3638
This work investigates the photoinduced energy transfer from poly(N‐vinylcarbazole) (PVK), as a donor material, to fac‐(2,2′‐bipyridyl)Re(CO)3Cl, as a catalyst acceptor, for its potential application towards CO2 reduction. Photoluminescence quenching experiments reveal dynamic quenching through resonance energy transfer in solid donor/acceptor mixtures and in solid/liquid systems. The bimolecular reaction rate constant at solution–film interfaces for the elementary reaction of the excited state with the quencher material could be determined as 8.8(±1.4)×1011 L mol?1 s?1 by using Stern–Volmer analysis. This work shows that PVK is an effective and cheap absorber material that can act efficiently as a redox photosensitizer in combination with fac‐(2,2′‐bipyridyl)Re(CO)3Cl as a catalyst acceptor, which might lead to possible applications in photocatalytic CO2 reduction. 相似文献
18.
Koji Tanaka 《Chemical record (New York, N.Y.)》2009,9(3):169-186
Proton dissociation of an aqua‐Ru‐quinone complex, [Ru(trpy)(q)(OH2)]2+ (trpy = 2,2′ : 6′,2″‐terpyridine, q = 3,5‐di‐t‐butylquinone) proceeded in two steps (pKa = 5.5 and ca. 10.5). The first step simply produced [Ru(trpy)(q)(OH)]+, while the second one gave an unusual oxyl radical complex, [Ru(trpy)(sq)(O?.)]0 (sq = 3,5‐di‐t‐butylsemiquinone), owing to an intramolecular electron transfer from the resultant O2? to q. A dinuclear Ru complex bridged by an anthracene framework, [Ru2(btpyan)(q)2(OH)2]2+ (btpyan = 1,8‐bis(2,2′‐terpyridyl)anthracene), was prepared to place two Ru(trpy)(q)(OH) groups at a close distance. Deprotonation of the two hydroxy protons of [Ru2(btpyan)(q)2(OH)2]2+ generated two oxyl radical Ru‐O?. groups, which worked as a precursor for O2 evolution in the oxidation of water. The [Ru2(btpyan)(q)2(OH)2](SbF6)2 modified ITO electrode effectively catalyzed four‐electron oxidation of water to evolve O2 (TON = 33500) under electrolysis at +1.70 V in H2O (pH 4.0). Various physical measurements and DFT calculations indicated that a radical coupling between two Ru(sq)(O?.) groups forms a (cat)Ru‐O‐O‐Ru(sq) (cat = 3,5‐di‐t‐butylcathechol) framework with a μ‐superoxo bond. Successive removal of four electrons from the cat, sq, and superoxo groups of [Ru2(btpyan)(cat)(sq)(μ‐O2?)]0 assisted with an attack of two water (or OH?) to Ru centers, which causes smooth O2 evolution with regeneration of [Ru2(btpyan)(q)2(OH)2]2+. Deprotonation of an Ru‐quinone‐ammonia complex also gave the corresponding Ru‐semiquinone‐aminyl radical. The oxidized form of the latter showed a high catalytic activity towards the oxidation of methanol in the presence of base. Three complexes, [Ru(bpy)2(CO)2]2+, [Ru(bpy)2(CO)(C(O)OH)]+, and [Ru(bpy)2(CO)(CO2)]0 exist as an equilibrium mixture in water. Treatment of [Ru(bpy)2(CO)2]2+ with BH4? gave [Ru(bpy)2(CO)(C(O)H)]+, [Ru(bpy)2(CO)(CH2OH)]+, and [Ru(bpy)2(CO)(OH2)]2+ with generation of CH3OH in aqueous conditions. Based on these results, a reasonable catalytic pathway from CO2 to CH3OH in electro‐ and photochemical CO2 reduction is proposed. A new pbn (pbn = 2‐pyridylbenzo[b]‐1,5‐naphthyridine) ligand was designed as a renewable hydride donor for the six‐electron reduction of CO2. A series of [Ru(bpy)3‐n(pbn)n]2+ (n = 1, 2, 3) complexes undergoes photochemical two‐ (n = 1), four‐ (n = 2), and six‐electron reductions (n = 3) under irradiation of visible light in the presence of N(CH2CH2OH)3. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 169–186; 2009: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.200800039 相似文献
19.
Nickel(II) Complexes of Pentadentate N5 Ligands as Catalysts for Alkane Hydroxylation by Using m‐CPBA as Oxidant: A Combined Experimental and Computational Study
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Dr. Muniyandi Sankaralingam Dr. Mani Balamurugan Prof. Dr. Mallayan Palaniandavar Dr. Prabha Vadivelu Dr. Cherumuttathu H. Suresh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11346-11361
A new family of nickel(II) complexes of the type [Ni(L)(CH3CN)](BPh4)2, where L=N‐methyl‐N,N′,N′‐tris(pyrid‐2‐ylmethyl)‐ethylenediamine (L1, 1 ), N‐benzyl‐N,N′,N′‐tris(pyrid‐2‐yl‐methyl)‐ethylenediamine (L2, 2 ), N‐methyl‐N,N′‐bis(pyrid‐2‐ylmethyl)‐N′‐(6‐methyl‐pyrid‐2‐yl‐methyl)‐ethylenediamine (L3, 3 ), N‐methyl‐N,N′‐bis(pyrid‐2‐ylmethyl)‐N′‐(quinolin‐2‐ylmethyl)‐ethylenediamine (L4, 4 ), and N‐methyl‐N,N′‐bis(pyrid‐2‐ylmethyl)‐N′‐imidazole‐2‐ylmethyl)‐ethylenediamine (L5, 5 ), has been isolated and characterized by means of elemental analysis, mass spectrometry, UV/Vis spectroscopy, and electrochemistry. The single‐crystal X‐ray structure of [Ni(L3)(CH3CN)](BPh4)2 reveals that the nickel(II) center is located in a distorted octahedral coordination geometry constituted by all the five nitrogen atoms of the pentadentate ligand and an acetonitrile molecule. In a dichloromethane/acetonitrile solvent mixture, all the complexes show ligand field bands in the visible region characteristic of an octahedral coordination geometry. They exhibit a one‐electron oxidation corresponding to the NiII/NiIII redox couple the potential of which depends upon the ligand donor functionalities. The new complexes catalyze the oxidation of cyclohexane in the presence of m‐CPBA as oxidant up to a turnover number of 530 with good alcohol selectivity (A/K, 7.1–10.6, A=alcohol, K=ketone). Upon replacing the pyridylmethyl arm in [Ni(L1)(CH3CN)](BPh4)2 by the strongly σ‐bonding but weakly π‐bonding imidazolylmethyl arm as in [Ni(L5)(CH3CN)](BPh4)2 or the sterically demanding 6‐methylpyridylmethyl ([Ni(L3)(CH3CN)](BPh4)2 and the quinolylmethyl arms ([Ni(L4)(CH3CN)](BPh4)2, both the catalytic activity and the selectivity decrease. DFT studies performed on cyclohexane oxidation by complexes 1 and 5 demonstrate the two spin‐state reactivity for the high‐spin [(N5)NiII?O.] intermediate (ts1hs, ts2doublet), which has a low‐spin state located closely in energy to the high‐spin state. The lower catalytic activity of complex 5 is mainly due to the formation of thermodynamically less accessible m‐CPBA‐coordinated precursor of [NiII(L5)(OOCOC6H4Cl)]+ ( 5 a ). Adamantane is oxidized to 1‐adamantanol, 2‐adamantanol, and 2‐adamantanone (3°/2°, 10.6–11.5), and cumene is selectively oxidized to 2‐phenyl‐2‐propanol. The incorporation of sterically hindering pyridylmethyl and quinolylmethyl donor ligands around the NiII leads to a high 3°/2° bond selectivity for adamantane oxidation, which is in contrast to the lower cyclohexane oxidation activities of the complexes. 相似文献
20.
Yuan‐Yuan Gu Yan‐Tuan Li Zhi‐Yong Wu Wei Sun Man Jiang 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(3):m115-m117
The title complex, bis[μ3‐cis‐N‐(2‐aminopropyl)‐N′‐(2‐carboxylatophenyl)oxamidato(3−)]‐1:2:4κ7N,N′,N′′,O:O′,O′′:O′′′;2:3:4κ7O′′′:N,N′,N′′,O:O′,O′′‐bis(2,2′‐bipyridine)‐2κ2N,N′;4κ2N,N′‐dichlorido‐1κCl,3κCl‐tetracopper(II) dihydrate, [Cu4(C12H12N3O4)2Cl2(C10H8N2)2]·2H2O, consists of a neutral cyclic tetracopper(II) system having an embedded centre of inversion and two solvent water molecules. The coordination of each CuII atom is square‐pyramidal. The separations of CuII atoms bridged by cis‐N‐(2‐aminopropyl)‐N′‐(2‐carboxylatophenyl)oxamidate(3−) and carboxyl groups are 5.2096 (4) and 5.1961 (5) Å, respectively. A three‐dimensional supramolecular structure involving hydrogen bonding and aromatic stacking is observed. 相似文献