A terminal borylene ruthenium complex: from B-H activation to reversible hydrogen release

Starting from RuHCl(H2)(PCy3)2, a terminal ruthenium mesitylborylene complex was obtained via double B-H bond activation of mesitylborane and concomitant release of dihydrogen, such a process being remarkably reversible.     

Selective alkylation of (hetero)aromatic amines with alcohols catalyzed by a ruthenium pincer complex

A readily available pincer ruthenium(II) complex catalyzes the selective monoalkylation of (hetero)aromatic amines with a wide range of primary alcohols (including pyridine-, furan-, and thiophene-substituted alcohols) with high efficiency when used in low catalyst loadings (1 mol %). Tertiary amine formation via polyalkylation does not occur, making this ruthenium system an excellent catalyst for the synthesis of sec-amines.     

Fluxional rearrangement in congested ruthenium(II) complexes containing pyrimidine- and/or pyridine-based dithioether ligands

The solvento species obtained by the treatment of cis-RuCl₂(N,N-L)₂ [L = di-2-pyridyl sulfide (dps), di-2-pyrimidyl sulfide (dprs)] with AgPF₆, reacted with dithioethers L′ [L′ = 2,6-bis(2-pyridylthiomethyl)pyridine (pytmp), 2,6-bis(2-pyrimidylthiomethyl)pyridine (prtmp) and 2,6-bis{2-(4-methyl)pyrimidylthiomethyl} pyridine (mprtmp)] to afford the compounds [Ru(N,N-L)₂(N,S-L′)][PF₆]₂. The ¹H NMR spectra indicate that L′ is chelated through S and N atoms with the formation of a four-membered ring. As a consequence, the ruthenium and sulfur atoms are stereogenic centers with ∆ and Λ and (R) and (S) configurations, respectively. NMR spectra, at low temperatures, show that two invertomers, of similar abundance, as enantiomeric couples ∆S, ΛR and ∆R, ΛS are present. In the methylene region, four AB systems are observed that in both the species contain two non-equivalent methylene groups. Variable-temperature NMR spectra and EXSY experiments show that the sulfur inversion produces an exchange between the invertomers. The one-dimensional band-shape analysis of the exchanging methylene signals showed that the energy barriers for the process are in the 43–52 kJ mol⁻¹ range. The possible mechanisms of the sulfur inversion are discussed.     

Selective CO2 conversion to formate in water using a CZTS photocathode modified with a ruthenium complex polymer

Highly selective photoelectrochemical CO(2) reduction (>80% selectivity) in water was successfully achieved by combining Cu(2)ZnSnS(4) (CZTS) with a metal-complex electrocatalyst. CZTS, a sulfide semiconductor that possesses a narrow band gap and consists of earth-abundant elements, is demonstrated to be a candidate photoabsorber for a CO(2) reduction hybrid photocatalyst.     

Excited-state annihilation in a homodinuclear ruthenium complex

Ultrafast excited-state annihilation in a homodinuclear ruthenium complex is observed. This coordination compound constitutes a model system for approaches towards artificial photosynthetic systems. The observation of pump-intensity dependent triplet-triplet annihilation highlights the importance of considering various loss mechanisms in the design of artificial photosynthetic assemblies.     

Synthesis and structure of a binuclear ruthenium 4-chlorobenzamidato complex

The compound Ru₂Cl(4-Cl-C₆H₄CONH)₄ was prepared by reaction of Ru₂Cl(O₂CCH₃)₄ with 4-Cl-C₆H₄CONH₂ at 180°C. Crystals of the composition Ru₂Cl(4-Cl-C₆H₄CONH)₄CH₃OH were obtained by slow diffusion of CH₃OH containing Et₄NCl into a Me₂SO solution of the compound. The structure of the crystalline product, which loses solvent of crystallization on removal from the mother liquor, was solved by X-ray crystallography by mounting a single crystal in a capillary containing the mother liquor. The crystals belong to the space group P1? (triclinic crystal system) with a = 12.731(3) Å, b = 14.389(3) Å, c = 12.604(3) Å, α = 103.41(2)°, β = 106.43(2)°, γ = 64.90(2)°, V = 1988.6(8) ų and Z = 2. There are two half ruthenium dimers linked by a Cl atom and an uncoordinated solvent CH₃OH molecule per asymmetric unit. The ruthenium dimers lie on two centers of inversion at 0, 0, 0 and 1/2, 0, 0. The chloride ions bridge dinuclear cations in the crystal, forming infinite zigzag chains. The average Ru-Ru distance is 2.296[1] Å and each ruthenium atom has a RuClN₂O₂ coordination sphere where the average Ru′-Ru-Cl angle is virtually linear (175.68[6]°). The metal oxidation states in the complex are + 2 and + 3, giving an average value of + 2.5. The arrangement of four bridging 4-Cl-benzamidato ligands is of the 2 : 2 type. The average Ru-N, Ru-O, Ru-Cl distances and Ru(1)-Cl(1)-Ru(2) angle are 2.036[6] Å, 2.044[5] Å, 2.583[2] Å and 117.26(8)°, respectively. The IR spectrum of the compound shows two N-H stretches at 3380 and 3340 cm^?1. The electronic spectrum of the compound in Me₂SO exhibits bands at 558 nm (ε = 340 M^?1 cm^?1), 425 nm (1000) and 320 nm (22,700).     

Synthesis and characterisation of a new helically chiral ruthenium complex

A new helically chiral hexacyclic phosphine, containing one thiophene ring was prepared in good yield via a five-step sequence involving a palladium-catalysed Mizoroki-Heck coupling reaction and classical oxidative photocyclisation. A mononuclear air stable ruthenium complex of this phosphine was also prepared and characterised.     

Visible light induced reversible extrusion of nitric oxide from a ruthenium(II) nitrosyl complex: a facile delivery of nitric oxide

The new ruthenium compound [Ru(NO)(pysiS4)]Br (3) (pysiS4 = 2,6-bis(3-triphenylsilyl-2-sulfanylphenylthiomethyl)pyridine), containing sterically bulky SiPh3 groups ortho to the thiolate donors, has been synthesized. In solution, 3 releases NO efficiently on exposure to visible light (lambda >/= 455 nm) at room temperature to afford [Ru(Br)(pysiS4)] (4). Treatment of 4 with NO yielded exclusively 3 without any metal-bound side reaction.     

Transfer hydrogenation with a ferrocene diamide ruthenium complex

The use of a 1,1'-ferrocenediamide ruthenium complex as a mediator for base-free transfer hydrogenation is reported. Ketones were transformed to their respective alcohols at room temperature in 36-99% conversions with turnover frequencies up to 339 h(-1).     

Thiocyanate linkage isomerism in a ruthenium polypyridyl complex

Ruthenium polypyridyl complexes have seen extensive use in solar energy applications. One of the most efficient dye-sensitized solar cells produced to date employs the dye-sensitizer N719, a ruthenium polypyridyl thiocyanate complex. Thiocyanate complexes are typically present as an inseparable mixture of N-bound and S-bound linkage isomers. Here we report the synthesis of a new complex, [Ru(terpy)(tbbpy)SCN][SbF(6)] (terpy = 2,2';6',2'-terpyridine, tbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine), as a mixture of N-bound and S-bound thiocyanate linkage isomers that can be separated based on their relative solubility in ethanol. Both isomers have been characterized spectroscopically and by X-ray crystallography. At elevated temperatures the isomers equilibrate, the product being significantly enriched in the more thermodynamically stable N-bound form. Density functional theory analysis supports our experimental observation that the N-bound isomer is thermodynamically preferred, and provides insight into the isomerization mechanism.     

Photoinduced ligand transformations in a ruthenium complex of dimethoxytetrapyridotetraazapentacene

The dinuclear ruthenium(II) complex [(phen)(2)Ru(tatpOMe)Ru(phen)(2)](4+) (2(4+); phen is 1,10-phenanthroline and tatpOMe is 10,21-dimethoxy-9,10,20,33-tetraazatetrapyrido[3,2-a:2'3'-c:3',2'-l:2',3'-n]pentacene) has been synthesized and characterized by (1)H NMR, ESI mass spectroscopy and elemental analysis. Loss of methoxy group from bridging ligand of complex 2(4+) due to irradiation is observed by (1)H NMR and photochemistry. The interrelated electronic properties UV-Vis, electrochemistry, photochemistry and molecular orbital calculation are analyzed and discussed on the bridging ligand of the complex 2(4+).     

The formation of a reversible complex between diethylcadmium and oxygen

From an investigation of the autoxidation of diethylcadmium (DEC) in n-heptane the formation of a reversible $\text{1}\text{2}$ DEC-oxygen complex has been established by a kinetic method.Some properties of this complex have been studied, viz. its ability to undergo spontaneous and catalytic transformation into bis(ethylperoxy)cadmium and its ultraviolet and infrared absorption spectra.     

Molecularly organized Langmuir-Blodgett films from a ruthenium biphosphine complex

Langmuir-Blodgett (LB) films from a ruthenium complex mer-[RuCl3 (dppb)(4-Mepy)] (dppb = PPh2 (CH2)4PPh2; 4-Mepy = 4-methylpyridine), termed Ru-Pic, display a distinct color, which is different from the coloration exhibited by cast films or chloroform solutions. The solution and cast films are red, while the LB films are green-bluish. The manifestation of the blue color in the LB film finds its explanation in a unique absorption band at 690 nm, which is associated with the oxidation of the phosphine moieties. Fluorescence emission and absorption-reflection infrared spectroscopy measurements revealed the molecular organization in the LB films. In contrast, cast films showed a random distribution of complexes. Surface-enhanced Raman scattering was also used in an attempt to identify the main interactions in Ru-Pic.     

A 2,3-naphthoquinodimethane complex of ruthenium

Treatment of 2,3-dimethylnaphthalene with BuLi·TMED (TMED = tetramethylethylenediamine) gives 2-lithiomethyl-3-methyl-naphthalene·TMED, which in tu     

Exceptionally facile CO addition to a saturated ruthenium complex

Synthesis and characterization of Cp*Ru[eta3-HC(PPh2NPh)2], 1, reveals it to have a "piano stool" structure with the ligand bound to Ru(II) via two N and the unique, sp3 hybridized carbon. While the analogous (cymene) Ru[eta3-HC(PPh2NPh)2]+ does not react with CO, under the same conditions, 1 adds one CO rapidly (25 degrees C, 1 atm CO). Characterization, including an X-ray structure determination, shows that CO has displaced one chelate ligand nitrogen, which then hangs off the molecule, free of Ru. DFT calculations reveal a possible mechanism via a remarkably low energy (+9.3 kcal/mol) intermediate, pendant N, but with one phenyl on phosphorus stabilizing Ru via donation from a C(ipso)=C(ortho) bond. DFT calculations show that the electronic energy change for binding CO is over 20 kcal/mol less favorable for cymene than for C5Me5- as ligand; the reactivity difference is thus thermodynamic in origin.