Chemistry Of Ruthenium Research Articles

Factors Affecting DMFC Fuel Cell Performances and Commercialization Consideration

. By combining novel platinum and ruthenium chemistry, we have succeeded in developing a new process for making thoroughly mixed Pt:Ru alloy with minimum undesirable phases at all loadings, as evidenced by XRD analysis. XRD analysis indicated that most other commercial PtRu products have oxide impurities (RuO2 xH2O), or unalloyed Ru phase. Correlation of RDE (rotating disk electrode) results and XRD spectra indicates these phases are ineffective for catalysis. These phases reduce the electronic interaction for weakening Pt-CO bond and the bimolecular reaction rate for CO removal. A good PtRu catalyst should have thorough atomic mixing with large surface area. Oxygen cathodes are also crucial for DMFC performance. Newly developed high performance Pt black cathode catalysts possess high surface areas. 60%-80% Pt on carbon shows similar performance and is easier to process. DMFC anode structure needs to reach a compromise between catalyst access by methanol and cross-over; cathode structure needs to find the compromise between catalyst wetting and proton conduction.

Henry Taube: Inorganic Chemist Extraordinaire

The numerous innovative contributions of Henry Taube to modern inorganic chemistry are briefly reviewed. Highlights include the determination of solvation numbers and lability, elucidation of substitution mechanisms, discovery and documentation of inner-sphere electron transfer, and discovery of the remarkable coordination chemistry of ruthenium and osmium ammine complexes with unsaturated ligands and mixed-valence complexes and their fundamental relationship to intramolecular electron transfer.

Synthesis, characterization, electro chemistry, catalytic and biological activities of ruthenium(III) complexes with bidentate N, O/S donor ligands

New hexa-coordinated ruthenium(III) complexes of the type [RuX2(EPh3)2(L)] (E=P or As; X=Cl or Br; L=monobasic bidentate Schiff base derived from the condensation of benzhydrazide with furfuraldehyde, 2-acetylfuran and 2-acetylthiophene) have been synthesized from the equimolar amounts of [RuX3(EPh3)3] or [RuBr3(PPh3)2(MeOH)] and Schiff bases in benzene. The new complexes have been characterized by analytical, spectral (IR, electronic and EPR), magnetic moment, and cyclic voltammetry. An octahedral structure has been tentatively proposed. All the complexes have exhibited catalytic activity for the oxidation of benzyl alcohol, cyclohexanol and cinnamylalcohol in the presence of N-methylmorpholine-N-oxide as co-oxidant. All the new complexes were found to be active against the bacteria such as E. coli, Pseudomonas, Salmonella typhi and Staphylococcus aureus. The activity was compared with standard Streptomycin.

27 Mechanisms of reactions in solution

Highlights of studies on mechanisms of reactions in solution include a description of a device to measure millisecond reactions in a droplet of solution and increasing application of theoretical techniques such as DFT to mechanisms of enzymes. There has been increased interest in systems involving Pt(II) square planar complexes and mechanistic studies are playing a significant part in the understanding of the role at molecular level of cisplatin and related anticancer drugs. The year 2003 has also seen significant developments in the understanding of the mechanisms of inorganic and organometallic chemistry of rhenium, ruthenium and osmium.

Analysis of Metallo‐Supramolecular Systems Using Single‐Molecule Force Spectroscopy

AbstractSingle‐molecule force spectroscopy has been used for the investigation of the rupture behavior of individual metallo‐supramolecular systems. For this purpose, a specifically designed unsymmetrical α,ω‐functionalized poly(ethylene oxide) has been employed for mono‐termination with a terpyridine ligand and subsequently for the attachment onto atomic force microscopy (AFM) tips and microscope slide substrates. Metallo‐supramolecular complexes were formed by the use of ruthenium(III)–ruthenium(II) chemistry. Vertical stretching with the AFM cantilever ruptured the coordinative bonds. The rupture force of individual bisterpyridine ruthenium(II) complexes was determined to be 95 pN at a force loading rate of 1 nN s–1. Simultaneous rupturing of multiple parallel metallo‐supramolecular bonds was also observed. Monte Carlo simulations corroborated the experimental observations. The presented results lay the basis for the application of such metallo‐supramolecular systems in advanced functional nanomaterials.

Novel [2+2+1] Cyclotrimerization of Alkynes Mediated by Bidentate Cyclopentadienyl-Phosphine Ruthenium Complexes

A remarkable change in reactivity of ruthenium cyclopentadienyl phosphine complexes toward alkynes HC⋮CR‘ (R‘ = Ph, C6H9, p-C6H4Me, p-C6H4OMe, ferrocenyl (Fc)) has been observed when the phosphine ligand is tethered onto the Cp ring via a two-carbon linker. That is, we contrast [RuCp(PR3)(CH3CN)2]PF6, dealt with before, with the bidentate cyclopentadienyl-phosphine complex [Ru(η5-C5H4CH2CH2-κ1P-PPh2)(CH3CN)2]PF6. While a metallacyclopentatriene complex (C) generated via oxidative coupling of two alkynes is a common first key intermediate, the onward reaction of C differs greatly. If the phosphine is tethered, a third alkyne molecule can be accommodated, resulting finally in an unusual C−C coupling process involving three alkynes and the tethered phosphine to give the cycloaddition product [Ru(η5-C5H4CH2CH2PH2-κ1C-CH-η4-C5H5)]+. According to DFT/B3LYP calculations this intriguing [2+2+1] alkyne cyclotrimerization proceeds via Ru−P bond dissociation, phosphine attack at the coordinated acetylene to yield a 1-metallacyclopropene, carbene vinyl insertion, and olefin vinyl insertion. On the other hand, for HC⋮CR‘ (R‘ = COOMe, COOEt, COMe) a [2+2+2] cyclotrimerization is favored. In sharp contrast, if the phosphine in C is simply unidentate, alkyne attack is prohibited, with alternative internal rearrangements taking place involving phosphine migration or 1,2-hydrogen shift. In these terms tethering may be considered as amounting to a delayed phosphine migration. Thus, the phosphine ligand in ruthenium chemistry is not necessarily just a spectator ligand but can switch over to an actor ligand.

Chemistry of Ruthenium(II) Alkyl Binap Complexes: Novel Bonding, Cyclometalation, and P−C Bond Splitting

Reactions of the bis-isopropyl and bis-cyclohexyl alkyl Binap ligands, 8 and 9, respectively, with [RuCl2(η6-p-cymene)]2 afford new dinuclear chloro-bridged Ru compounds which contain the Binap ligands as six- rather than four-electron donors. A backbone double bond proximate to one of the P-donors complexes the metal atom. NMR details of the olefin bonding plus isomerization reactions involving loss of the olefin complexation are reported. Reactions of 8 or 9 with [Ru(OAc)2(η6-p-cymene)] result in slow P−C bond cleavage and cyclometalation, instead of affording the anticipated [Ru(OAc)2(Binap)] complex. The new cyclometalated complexes, 15 and 16, contain the complexed R2P−O(CO)CH3 ligand and arise (presumably) via acetate attack at phosphorus with the electrons in the P−C bond moving to the ruthenium atom. The solid-state structure of one of these, the cyclohexyl analogue, 16, is reported and represents a rare structural example of a molecule with three different chelate ligands. The complexed R2P−O(CO)CH3 ligand is readily hydrolyzed in wet triflic acid to afford the R2P(OH) donor and an η6-arene ligand (via Ru−C protonation).

Research Committee on Ruthenium and Technetium Chemistry in PUREX System, Organized by the Atomic Energy Society of Japan

The paper summarizes the activity of the committee “Ruthenium and Technetium Chemistry in the PUREX System,” with a focus on basic information on technetium behavior in the PUREX process, the principles of plant design, and the behavior during the final waste treatment.

Bis(pyrazol-1-yl)acetato Ligands in Ruthenium Chemistry: Syntheses and Structures of Ruthenium(II) and Ruthenium(III) Complexes with bpza and bdmpza

Bis(pyrazol-1-yl)acetato Ligands in Ruthenium Chemistry: Syntheses and Structures of Ruthenium(II) and Ruthenium(III) Complexes with bpza and bdmpza

The chemistry of ruthenium complexes of 1,2-dicyanoethylene dithiolate (mnt2–). Synthesis and characterization of [RuIV/III(mnt)3]2–/3– and the derivatives trans-[RuIII(mnt)2(PPh3)2]–, trans-[RuIII(mnt)2(py)2]– and trans-[RuIV(mnt)2(Br)2]2–

The chemistry of ruthenium(III) and ruthenium(IV) complexes with 1,2-dicyanoethylene dithiolate(2−) (mnt2−) as ligand has been investigated. The tris-complex [RuIII(mnt)3]3− is readily prepared and oxidized to [RuIV(mnt)3]2−. Both complex anions are characterized by X-ray structural analysis. Ligand substitution behavior of the anions has been examined. Reactions of [RuIII(mnt)3]3− with triphenylphosphine and pyridine are sluggish while reactions of [RuIV(mnt)3]2− with these nucleophiles are complex, involving reduction by the displaced mnt2− ligand, to give trans-[RuIII(mnt)2(PPh3)2]− and trans-[RuIII(mnt)2(py)2]− respectively. A ruthenium(IV) complex, trans-[RuIV(mnt)2(Br)2]2−, is formed on treatment of [RuIV(mnt)3]2− with Br2. These three products have also been characterized by X-ray crystallography. In solution, the complexes trans-[RuIII(mnt)2(PPh3)2]− and trans-[RuIV(mnt)2(Br)2]2− both lose one axial ligand in rapidly established equilibria. The complex, [RuIV(mnt)3]2−, undergoes an unusual photochemical rearrangement in the presence of oxygen resulting in formation of [RuII(mnts)2]2− where mnts2− is a novel tridentate sulfur-bound ligand.

A Facile Route to Carbonylhalogenometal Complexes (M = Rh, Ir, Ru, Pt) by Dimethylformamide Decarbonylation

Dimethyl formamide (DMF) can be a convenient source of the carbonyl ligand in the coordination chemistry of rhodium, ruthenium, iridium, and platinum. We have undertaken a thorough study concerning the course of this reaction. In a first step, DMF-containing complexes are produced, which is usually accompanied by chloride redistribution. Then, upon refluxing, carbonyl species in the same oxidation state are obtained, presumably as a result of HCl-mediated DMF decomposition. Provided that water levels are kept low, reduction can occur to provide the complexes [NH2(CH3)2][RhCl2(CO)2], [NH2(CH3)2][RuCl3(CO)2(DMF)], [RuCl2(CO)2(DMF)2], and [NH2(CH3)2][IrCl2(CO)2]. In the case of platinum, reduction is not effective and [NH2(CH3)2][PtCl3(CO)] is obtained. No carbonylpalladium species can be synthesized in this way, the reaction producing copious amounts of colloidal metal. Adding phosphanes to these chlorocarbonyl-containing solutions allows easy, one-step syntheses of a variety of complexes.

ChemInform Abstract: Crown‐Anellated p‐Phenylenediamine Derivatives as Electrochemical and Fluorescence Responsive Chemosensors: Synthesis via Arene—Ruthenium Chemistry.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Crown-annelated p-phenylenediamine derivatives as electrochemical and fluorescence responsive chemosensors: synthesis via arene–ruthenium chemistry

The synthesis of two crown annelated tetraalkyl-p-phenylenediamine derivatives, via sequential SNAr reactions on (p-dichlorobenzene)RuCp cationic complexes, is described.

Chemistry of ruthenium with some dioxime ligands. Syntheses, structures and reactivities

Reaction of two dioxime ligands, viz. dimethylglyoxime (H 2dmg) and diphenylglyoxime (H 2dpg), (abbreviated in general as H 2L, where H stands for the oxime protons) with [Ru(PPh 3) 3Cl 2] in 1:1 mole ratio affords complexes of type [Ru(PPh 3) 2(H 2L)Cl 2]. Structure of the [Ru(PPh 3) 2(H 2dpg)Cl 2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium is N 2P 2Cl 2 with the two PPh 3 ligands in trans and the two chlorides in cis positions. Reaction of the dioxime ligands with [Ru(PPh 3) 3Cl 2] in 2:1 mole ratio in the presence of a base affords complexes of type [Ru(PPh 3) 2(HL) 2]. Structure of the [Ru(PPh 3) 2(Hdmg) 2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium is N 4P 2 with the two PPh 3 ligands in trans positions. Reaction of the [Ru(PPh 3) 2(H 2dpg)Cl 2] complex with a group of bidentate acidic ligands, viz. picolinic acid (Hpic), quinolin-8-ol (Hq) and 1-nitroso-2-naphthol (Hnn), (abbreviated in general as HL′, where H stands for the acidic proton) in the presence of a base affords complexes of type [Ru(PPh 3) 2(H 2dpg)(L′)] + isolated as perchlorate salts. All the complexes are diamagnetic (low-spin d 6, S=0) and in dichloromethane solution show several intense MLCT transitions in the visible region. Cyclic voltammetry on all the complexes shows a reversible ruthenium(II)–ruthenium(III) oxidation within 0.36–0.98 V versus SCE followed by a quasi-reversible ruthenium(III)–ruthenium(IV) oxidation within 0.94–1.60 V versus SCE.

The triphenylmethyl group as thiol protection during ruthenium-promoted synthesis of tetraalkyl- p-phenylenediamine systems having alkanethiol side chains

The use of triphenylmethyl as thiol protecting group during the construction of thioalkyl-substituted tetraalkyl- p-phenylenediamine derivatives, via arene–ruthenium chemistry, is reported.

Chemistry of ruthenium with some phenolic ligands: synthesis, structure and redox properties

Reaction of three phenolate ligands, viz. salicylaldehyde (HL 1), 2-hydroxyacetophenone (HL 2) and 2-hydroxynaphthylaldehyde (HL 3), (abbreviated in general as HL, where H stands for the phenolic proton) with [Ru(PPh 3) 3Cl 2] in 1:1 mole ratio gives complexes of the type [Ru(PPh 3) 2(L)Cl 2]. The structure of the [Ru(PPh 3) 2(L 2)Cl 2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium is O 2P 2Cl 2 with a cis– trans– cis geometry, respectively. The [Ru(PPh 3) 2(L)Cl 2] complexes are one-electron paramagnetic (low-spin d 5, S=1/2) and show rhombic ESR spectra in 1:1 dichloromethane–toluene solution at 77 K. In dichloromethane solution the [Ru(PPh 3) 2(L)Cl 2] complexes show several intense LMCT transitions in the visible region. Reaction between the phenolic ligands and [Ru(PPh 3) 3Cl 2] in 2:1 mole ratio in the presence of a base affords the [Ru(PPh 3) 2(L) 2] complexes in two isomeric forms. 1H NMR spectra of one isomer shows that it does not have any C 2 symmetry and has the cis– cis– cis disposition of the three sets of donor atoms. 1H NMR spectra of the other isomer shows that it has C 2 symmetry. The structure of the isomer of the [Ru(PPh 3) 2(L 1) 2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium is O 4P 2 with a cis– trans– cis disposition of the carbonylic oxygens, phenolate oxygens and phosphorus atoms, respectively. The [Ru(PPh 3) 2(L) 2] complexes are diamagnetic (low-spin d 6, S=O) and show intense MLCT transitions in the visible region. Cyclic voltammetry on the [Ru(PPh 3) 2(L)Cl 2] complexes shows a ruthenium(III)ruthenium(II) reduction near −0.3 V versus SCE and a ruthenium(III)ruthenium(IV) oxidation in the range 1.08–1.24 V versus SCE. Cyclic voltammetry on both isomers of the [Ru(PPh 3) 2(L) 2] complexes shows a ruthenium(II)ruthenium(III) oxidation within 0.09–0.41 V versus SCE, followed by a ruthenium(III)-ruthenium(IV) oxidation within 1.31–1.52 V versus SCE.

ChemInform Abstract: Aqueous Organometallic Chemistry of Ruthenium(II): Aquo Carbonyl Derivatives and Related Ethene Hydrocarboxylation in Fully Aqueous Solvent

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Ruthenium(II) chemistry of phosphorus-based ligands, Ph 2PN(R)PPh 2 (R=Me or Ph) and Ph 2PN(Ph)P(E) Ph 2 (E=S or Se). Solution thermochemical study of ligand substitution reactions in the Cp′RuCl(COD) (Cp′=Cp, Cp*; COD=cyclooctadiene) system

The enthalpies of reactions of Cp′RuCl(COD) (Cp′=Cp, Cp*; COD=cyclooctadiene) with bis(phosphino)amines of the type Ph 2PN(R)PPh 2(R=Me 1 or R=Ph 2) and the monochalcogen derivatives Ph 2PN(Ph)P(E)Ph 2(E=S 3 or Se 4) leading to the formation of Cp′RuCl(PNP) and Cp′RuCl{PNP(E)} complexes, respectively, have been measured by anaerobic solution calorimetry in THF at 30°C. These reactions are clean and quantitative. The synthesis and characterization of new organoruthenium complexes is reported. Comparisons with enthalpy data in this two related organoruthenium systems and other similar organometallic systems are also presented.

The use of macrocyclic and polydentate ligands in ruthenium organometallic chemistry

This report deals with two stereochemically different tridentate N 3-ligands suitable as ancillary ligands in the organometallic chemistry of ruthenium. [{Ru( p-cymene)(Cl)} 2(μ-Cl) 2] assisted the template synthesis of a tridentate N 3-macrocycle derived from 2-aminobenzaldehyde, thus forming [Ru(η 3-C 21H 15N 3)Ru( p-cymene)] 2+2Cl −, 1. The ligand 2, PyrPic·H, derived from the condensation of pyrrole-2-aldehyde and 2-picolylamine, functions as a monoanionic tridentate ligand in the reaction with [{Ru(COD)(Cl)} 2(μ-Cl) 2] leading to [Ru(COD)(Cl)(PyrPicH 2)], 4, which undergoes the ionization of the RuCl bond both in pyridine or in THF in the presence of AgTf, leading to [Ru(PyrPicH)Py 3] +Cl −, 5 and [Ru(COD)(PyrPicH)Tf], 6, respectively. The alkylation of 4 using LiMe led to [(RuMe)(PyrPicH)(COD)], 7, which undergoes a methane elimination to yield [Ru 2(μ-PyrPic) 2(COD) 2], 8. The reaction of potassiumpyren [pyren= N, N′-ethylenebis(2-pyrrolyliminato)dianion], 10, with [{Ru(COD)(Cl)} 2(μ-Cl) 2] led to the Ru-macrocyclic derivative [Ru(Pyren)(COD)], 11, where COD fills two cis-positions around ruthenium. Extended Hückel calculations have been carried out on the two stereochemically different RuN 3 fragments having a facial (see complex 1) and a meridional ( 4, 5, 6, 7 and 8) arrangements in order to identify the difference in the frontier orbitals for the metal reactivity.

Aqueous Organometallic Chemistry of Ruthenium(II). Aquo Carbonyl Derivatives and Related Ethene Hydrocarboxylation in Fully Aqueous Solvent.

A series of new water soluble and stable organometallic compounds is reported, and the peculiar role of water in their formation and stabilization is documented together with their catalytic properties in aqueous solution. The complex fac-Ru(OCOCF(3))(2)(CO)(3)(H(2)O) (1) constitutes the entry to a new type of aqueous organometallic chemistry. The substitution of trifluoroacetato ligands by H(2)O yields [fac-Ru(CO)(3)(H(2)O)(3)](2+) (2), isolated as the tetrafluoroborate derivative, the first structurally characterized complex bearing CO and H(2)O ligands only. In water, 2 undergoes nucleophilic attack by the solvent yielding [fac-Ru(COOH)(CO)(2)(H(2)O)(3)](+) (3), followed by CO(2) elimination to give [fac-RuH(CO)(2)(H(2)O)(3)](+) (4), a ruthenium(II) hydride devoid of group-15-donor coligands and stable toward strong acids. 4 inserts ethene in water to give [fac-Ru(C(2)H(5))(CO)(2)(H(2)O)(3)](+) (5), an exceptionally inert alkyl complex which inserts CO yielding [fac-Ru(C(O)C(2)H(5))(CO)(2)(H(2)O)(3)](+) (6). Attempts to isolate the mononuclear cationic acyl complex gave the tetranuclear Ru(4)(C(O)C(2)H(5))(4)(OH)(2)(CF(3)SO(3))(2)(CO)(8) (7). At 140 degrees C the mononuclear organometallic complexes become labile intermediates of a Reppe hydrocarboxylation of ethene in fully aqueous solvent.