Ruthenium(II)‐Catalyzed Decarboxylative C−H Activation: Versatile Routes to meta‐Alkenylated Arenes

Ruthenium(II) bis(carboxylate)s proved highly effective for two decarboxylative C−H alkenylation strategies. The decarboxylation proceeded efficiently at rather low temperatures. The unique versatility of the decarboxylative ruthenium(II) catalysis is reflected in the oxidative olefinations with alkenes as well as the redox‐neutral hydroarylations of alkynes.     

Comparative Study of Ruthenium(II) and Ruthenium(III) Complexes with the Ligand dmbpy (dmbpy = 4, 4′‐Dimethyl‐2, 2′‐bipyridine)

The complex cis‐[Ru^III(dmbpy)₂Cl₂](PF₆) ( 2 ) (dmbpy = 4, 4′‐dimethyl‐2, 2′‐bipyridine) was obtained from the reaction of cis‐[Ru^II(dmbpy)₂Cl₂] ( 1 ) with ammonium cerium(IV) nitrate followed by precipitation with saturated ammonium hexafluoridophosphate. The ¹H NMR spectrum of the Ru^III complex confirms the presence of paramagnetic metal atoms, whereas that of the Ru^II complex displays diamagnetism. The ³¹P NMR spectrum of the Ru^III complex shows one signal for the phosphorus atom of the PF₆^– ion. The perspective view of each [Ru^II/III(dmbpy)₂Cl₂]^0/+ unit manifests that the ruthenium atom is in hexacoordinate arrangement with two dmbpy ligands and two chlorido ligands in cis position. As the oxidation state of the central ruthenium metal atom becomes higher, the average Ru–Cl bond length decreases whereas the Ru–N (dmbpy) bond length increases. The cis‐positioned dichloro angle in Ru^III is 1.3° wider than that in the Ru^II. The dihedral angles between pair of planar six‐membered pyridyl ring in the dmbpy ligand for the Ru^II are 4.7(5)° and 5.7(4)°. The observed inter‐planar angle between two dmbpy ligands in the Ru^II is 89.08(15)°, whereas the value for the Ru^III is 85.46(20)°.     

Synthesis and Characterization of Dinuclear Ruthenium(II) Complexes Based on 4,4′‐Bipyridyl Type Bridging Ligands

The synthesis, spectroscopic, electrochemical and photophysical characterization of a series of dinuclear ruthenium(II) complexes of the type [(bpy)₂Ru(NnN)₂RuCl(bpy)₂](PF₆)₃, where NnN = 4,4′‐bipyridyl (N0N), 1,2‐bis(4‐pyridyl)ethylene (NEN), 1,2‐bis(4‐pyridyl)ethane (N2N), and 4,4′‐trimethylenedipyridine (N3N) are reported. The photophysical and electrochemical properties are discussed with particular emphasis on the ability of the bridging ligands to support intercomponent interaction.     

Ruthenium(II)‐Komplexe mit orthometallierten O'Donnell Schiffbasen (Diphenylmethylenglycinester) [1]

Ruthenium(II) Complexes of Orthometallated O'Donnell Schiff Bases (Diphenylmethylene Glycine Esters) [1] The reaction of diphenyl methylene glycine esters with [Ru(PPh₃)₃Cl₂] gives the orthometallated complexes [Ru(PPh₃)₂(Cl){(C₆H₄)(C₆H₅)C=NCH₂CO₂R}] (R = H, Et, CMe₃) in which the ester group is coordinated to the ruthenium atom and which were characterized by IR, NMR, MS data and by cyclovoltammetry.     

Iron(II)‐Catalyzed Biomimetic Aerobic Oxidation of Alcohols

We report the first Fe^II‐catalyzed biomimetic aerobic oxidation of alcohols. The principle of this oxidation, which involves several electron‐transfer steps, is reminiscent of biological oxidation in the respiratory chain. The electron transfer from the alcohol to molecular oxygen occurs with the aid of three coupled catalytic redox systems, leading to a low‐energy pathway. An iron transfer‐hydrogenation complex was utilized as a substrate‐selective dehydrogenation catalyst, along with an electron‐rich quinone and an oxygen‐activating Co(salen)‐type complex as electron‐transfer mediators. Various primary and secondary alcohols were oxidized in air to the corresponding aldehydes or ketones with this method in good to excellent yields.     

Copper(I)‐Catalyzed Three‐Component Reaction of Terminal Propargyl Alcohols,Aldehydes, and Amines: Synthesis of 3‐Amino‐2‐pyrones and 2,5‐Dihydrofurans

A novel copper(I)‐catalyzed three‐component reaction for the efficient synthesis of 3‐amino‐2‐pyrones and 2,5‐dihydrofurans from propargyl alcohols, aldehydes, and amines has been developed. The starting materials are easily available and the scope of this method is broad. Through mechanistic studies, it is believed that the three‐component reaction consists of an A³‐coupling to propargylic amine, alkyne–allene isomerization, and intramolecular cyclization of the allenol to form a furan. In case of using ethyl glyoxalate as the aldehyde, a ring‐opening, lactonization, and isomerization process affords the 3‐amino‐2‐pyrones.     

RuS4Cl12 und Ru2S6Cl16, zwei neue Ruthenium(II)‐Komplexe mit SCl2‐Liganden

RuS₄Cl₁₂ and Ru₂S₆Cl₁₆, Two New Ruthenium(II) Complexes with SCl₂ Ligands Ru powder was reacted with SCl₂ in closed silika ampoules at 140 °C. From the black solution three compounds RuS₄Cl₁₂ 1 , Ru₂S₆Cl₁₆ 2 , and Ru₂S₄Cl₁₃ 3 could be crystallized and characterized by x ray analysis. Black crystals of 1 (monoclinic, a = 9.853(1) Å, b = 11.63(1) Å, c = 15.495(1) Å, β = 105.23(1)°, space group P2₁/c, z = 4) are identified as Trichlorsulfonium‐tris(dichlorsulfan)trichloro‐ruthenat(II) SCl₃[RuCl₃(SCl₂)₃]. In the structure the complex anions fac‐[RuCl₃(SCl₂)₃]^– and the cations [SCl₃]⁺ are connected to ion pairs by three chlorine bridges. The brown crystals of 2 (triclinic, a = 7.754(2) Å, b = 7.997(2) Å, c = 10.708(2) Å, α = 103.74(3)°, β = 98.44(3)°, γ = 108.58(3)°, space group P‐1, z = 1) contain the binuclear complex Bis‐μ‐chloro‐dichloro‐hexakis(dichlorsulfan)‐diruthenium(II), (SCl₂)₃ClRu(μ‐Cl)₂RuCl(SCl₂)₃ with two fac‐RuCl₃(SCl₂)₃‐units connected by two chlorine bridges. 3 was identifyed as a known mixed valence Ru(II,III) binuclear complex [Cl₂(SCl₂)Ru(μ‐Cl)₃Ru(SCl₂)₃]. The vibrational spectra and the thermal behaviour of the compounds are discussed.     

Synthesis of a Ruthenium(II) Compound based on 5‐(2‐Pyrimidyl)‐1H‐tetrazole for Photodynamic Therapy

Ru^II compounds have been universally investigated due to their unique physical and chemical properties. In this paper, a new Ru^II compound based on 2,2′‐bipy and Hpmtz [2,2′‐bipy = 2,2′‐bipyridine, Hpmtz = 5‐(2‐pyrimidyl)‐1H‐tetrazole], namely [Ru(2,2′‐bipy)₂(pmtz)][PF₆] · 0.5H₂O was prepared and characterized by elemental analysis, IR and single‐crystal X‐ray diffraction. [Ru(2,2′‐bipy)₂(pmtz)][PF₆] · 0.5H₂O shows a mononuclear structure and forms a three‐dimensional network by non‐classic hydrogen bonds. The ability of generation of ROS (reactive oxygen species) makes it has a low phototoxicity IC₅₀ (half‐maximal inhibitory concentration) after Xenon lamp irradiation on Hela cells in vitro. The results demonstrate that [Ru(2,2′‐bipy)₂(pmtz)][PF₆] · 0.5H₂O with high light toxicity and low dark toxicity may be a potential candidate for photodynamic therapy.     

Synthese und Struktur von Ruthenium(II)‐Komplexen mit Triazenido‐ und Pentaazadienido‐Liganden

Synthesis and Crystal Structure of Ruthenium(II) Complexes with Triazenido and Pentaazadienido Ligands The ruthenium(II) triazenido complex [RuCl(ClC₆H₄N₃C₆H₄Cl)(p‐cymene)] ( 1 ) is obtained by the reaction of silver bis(p‐chlorphenyl)triazenid with [RuCl₂(p‐cymene)]₂ in CH₂Cl₂, and forms air stable, orange yellow crystals. It crystallizes as 1 ·CH₂Cl₂ in the orthorhombic space group Pbca with the lattice parameters a = 3134.3(3), b = 2105.7(2), c = 769.15(4) pm and Z = 8. In the diamagnetic mononuclear complex 1 the chelating triazenido ligand coordinates with the atoms N(1) and N(3). p‐Cymene binds η⁶ with its C₆ ring. The reaction of the etherphosphane complex [RuCl₂(Ph₂PCH₂C₄H₇O₂)₂] with 1, 3‐bis(p‐tolyl)triazenid in THF yields the complex [RuCl(tolyl‐N₃‐tolyl)(Ph₂PCH₂C₄H₇O₂)₂] ( 2 ). 2 forms monoclinic, red crystals with the space group P2₁/c and a = 1521.0(2), b = 1451.8(2), c = 2073.7(2) pm, β = 99.29(1)° and Z = 4. It is air stable and diamagnetic. The triazenide ion coordinates with the atoms N(1) and N(3). One of the two etherphosphane ligands is chelating and coordinates with the P atom and one O atom, while the other ligand binds in a monodentate fashion with its P atom, resulting in a coordination number of six for the Ru^II. [Ag(tolyl‐N₅‐tolyl)]₂ reacts in THF with [RuCl₂(C₆H₆)]₂ to afford the air stable, diamagnetic pentaazadienido complex [RuCl(tolyl‐N₅‐tolyl)(C₆H₆)] ( 3 ). 3 forms monoclinic, red crystals with the space group P2₁/c and a = 1462.4(1), b = 1056.51(8), c = 1371.4(1) pm, β = 114.36(1)° and Z = 4. The chelating pentaazadienido ligand coordinates with the atoms N(1) and N(3) at the divalent Ru atom. The benzene molecule binds η⁶ with its π system.