Ruthenium Coordination Research Articles

Scanning Electrochemical Microscopy. 43. Investigation of Oxalate Oxidation and Electrogenerated Chemiluminescence across the Liquid−Liquid Interface

To treat the problem of oxalate oxidation in an aqueous phase by a Ru(III) species (mediator) generated in an immiscible nonaqueous phase (benzonitrile) at a scanning electrochemical microscope (SECM tip), the theory of the feedback mode of the SECM is extended to include both finite heterogeneous electron transfer (ET) kinetics at the substrate and homogeneous decomposition of the mediator. As for the classical electrochemical (EC) scheme, a zone diagram is constructed showing pure ET heterogeneous kinetic control, pure homogeneous kinetic (C) control (insulating behavior), and mixed EC kinetic control. The model allows interpretation of the anomalous approach curves obtained for oxalate oxidation by a ruthenium(III) coordination complex at the benzonitrile (BN)−water interface and allows calculation of the rate constant for the ET at the liquid−liquid interface. Attempts are made to relate these rates to the homogeneous rate constant in terms of Marcus theory. The second ET (oxidation of CO2•-) at the l...

Topoisomerase II poisoning by indazole and imidazole complexes of ruthenium.

Trans-imidazolium (bis imidazole) tetrachloro ruthenate (RuIm) and trans-indazolium (bis indazole) tetrachloro ruthenate (RuInd) are ruthenium coordination complexes, which were first synthesized and exploited for their anticancer activity. These molecules constitute two of the few most effective anticancer ruthenium compounds. The clinical use of these compounds however was hindered due to toxic side effects on the human body. Our present study on topoisomerase II poisoning by these compounds shows that they effectively poison the activity of topoisomerase II by forming a ternary cleavage complex of DNA, drug and topoisomerase II. The thymidine incorporation assays show that the inhibition of cancer cell proliferation correlates with topoisomerase II poisoning. The present study on topoisomerase II poisoning by these two compounds opens a new avenue for renewing further research on these compounds. This is because they could be effective lead candidates for the development of more potent and less toxic ruthenium containing topoisomerase II poisons. Specificity of action on this molecular target may reduce the toxic effects of these ruthenium-containing molecules and thus improve their therapeutic index.

Ruthenium(III) Coordination to the Exocyclic Nitrogen of 9-Methyladenine and Stabilisation of the Rare Imine Tautomer by Intramolecular Hydrogen Bonding

The X-ray structure of trans-[RuCl3(dmtp)2(9-MeAde)] shows that this compound is the first crystallographic example of a ruthenium(III) complex with an adenine derivative coordinated as a monodentate ligand through the exocyclic N6 nitrogen; two intramolecular hydrogen bonds stabilise the coordination of the adenine, which is present as a neutral ligand in the rare tautomeric imine form with a unique short C6−N6 distance of 1.293(3) Å.

Complexed bridging ligands: oxorhenium(V) compounds with mono-coordinated pyrazine or pyrimidine as possible building blocks for the construction of polynuclear architectures †

The reactivity of oxorhenium(V) precursors with simple diaza ligands such as pyrazine (pyz) and pyrimidine (pym) was investigated. Treatment of ReOCl3(Me2S)(OPPh3) or ReO(OEt)Cl2(PPh3)2 with an excess of pyz or pym under a range of different conditions yielded a series of oxo- and dioxo-rhenium(V) compounds with one or more terminally coordinated diaza ligands, namely the dinuclear species Re2O3Cl4(pyz)41 and Re2O3Cl4(pym)42, and the mononuclear complexes trans,trans,trans-ReO(OEt)Cl2(pyz)23, trans,trans,trans-ReO(OEt)Cl2(pym)24, trans,trans,trans-ReO(OEt)Cl2(pyz)(PPh3) 5, and [trans-ReO2(pyz)4][PF6] 7. The new compounds were characterized in solution and in the solid state by common spectroscopic techniques; the crystal structures of 1, 3, 5, and 7 were also determined. The dinuclear species 1 presents a nearly linear ORe–O–ReO group and each Re atom brings two cis chlorides and two mono-coordinated pyrazine units. Crystals of the dioxo species 7 contain one NaPF6 and two H2O molecules of crystallization; the four pyrazine bases terminally bound to Re interact also with Na, forming slightly distorted square cavities (side length ca. 7.4 Å), with Na and Re alternating in the corners. Density functional calculations of the excitation spectra of 3 and 4 were also performed with the aim of investigating in more detail the influence of the nature of the nitrogen ligand on the experimental visible spectra. A preliminary investigation of the reactivity of compound 3 towards coordination compounds and metalloporphyrins was also made. Treatment of 3 with a slight excess of the ruthenium(II) complex cis,fac-RuCl2(Me2SO)3(CO) yielded the linear trinuclear species [{trans,trans,trans-ReO(OEt)Cl2}(μ-pyz)2{cis,cis,cis-RuCl2(Me2SO-S)2(CO)}2], in which both ends of the rhenium complex are bound to a ruthenium coordination compound. Similarly, treatment of 3 with an excess of [Ru(TPP)(CO)(EtOH)] (TPP = tetraphenylporphyrinate) led to the symmetrical trinuclear species [{trans,trans,trans-ReO(OEt)Cl2}(μ-pyz)2{Ru(TPP)(CO)}2], consisting of two face-to-face ruthenium porphyrins axially connected through a coordination compound; the corresponding canted trinuclear compound [{trans,trans,trans-ReO(OEt)Cl2}(μ-pym)2{Ru(TPP)(CO)}2] was similarly obtained from 4. Thus the new oxorhenium(V) species can be considered as potentially useful basic building blocks for the self-assembly of polynuclear architectures.

Ruthenium(III) Coordination to the Exocyclic Nitrogen of 9-Methyladenine and Stabilisation of the Rare Imine Tautomer by Intramolecular Hydrogen Bonding

The X-ray structure of trans-[RuCl3(dmtp)2(9-MeAde)] shows that this compound is the first crystallographic example of a ruthenium(III) complex with an adenine derivative coordinated as a monodentate ligand through the exocyclic N6 nitrogen; two intramolecular hydrogen bonds stabilise the coordination of the adenine, which is present as a neutral ligand in the rare tautomeric imine form with a unique short C6−N6 distance of 1.293(3) Å.

99Ru NMR Spectroscopy of Organometallic and Coordination Complexes of Ruthenium(II)

The ruthenium(II) organometallic and coordination complexes of type Ru(X)(Y)(CO)2(i-Pr-DAB) (i-Pr-DAB = 1,4-diisopropyl-1,4-diaza-1,3-butadiene; X, Y = Cl, Br, I, Me, Et, i-Pr, neo-Pe, Ph3Sn, Me3Sn, Ph3Pb, Ph3Ge, Mn(CO)5, RuCp(CO)2) have been analyzed by means of 99Ru NMR spectroscopy. The 99Ru NMR resonances for these compounds are generally sharp, allowing scalar couplings to group 14 nuclei to be observed. Correlation times τc have been determined from NOE factors and 13C T1 values for selected compounds and were found to parallel the molecular weight of the compounds studied. The M−Ru−M‘ and M−Ru−X complexes have 99Ru NMR resonances in distinct chemical shift regions. In the series M−Ru−M‘ a correlation between the inverse of the crystal field splitting energy ΔE and δ(99Ru) exists. These complexes have a HOMO which is delocalized over the M−Ru−M‘ σ system and a LUMO which has predominantly π*-DAB character; therefore, (ΔE)-1 is dominant in the paramagnetic shielding of the ruthenium nucleus. The diff...

Electrogenerated Chemiluminescence. 65. An Investigation of the Oxidation of Oxalate by Tris(polypyridine) Ruthenium Complexes and the Effect of the Electrochemical Steps on the Emission Intensity

The homogeneous oxidation of oxalate has been investigated at an ultramicroelectrode by means of redox catalysis with different iron and ruthenium coordination complexes. Kinetically, the process is governed by the first electron transfer. It can be rationalized by Marcus theory. When the electron acceptor is a ruthenium coordination complex, the second electron transfer can generate a luminescent excited state of the ruthenium. This electrochemiluminescent process is related, in a first approximation, to the catalytic efficiency of the homogeneous oxalate oxidation, but also to the different competing routes for the second electron transfer (oxidation of CO2•-). The effect of the pH and the ionic strength on the redox catalysis and the light emission are discussed.

A novel ruthenium carbene dimer that is active in the metathesis of internal alkenes; the crystal structure of Ru2(CHPh)2(CF3CO2)2(μ-CF3CO2)2(PCy3)2(μ-H2O)

Abstract The reaction of Ru(CHPh)Cl 2 (PCy 3 ) 2 ( 1 ) with two equivalents of CF 3 CO 2 Ag gives Ru 2 (CHPh) 2 (CF 3 CO 2 ) 2 (μ-CF 3 CO 2 ) 2 (PCy 3 ) 2 (μ-H 2 O) ( 2 ) in high yield. The crystal structure of 2 reveals that the ruthenium atoms are bridged by two trifluoroacetate groups and one water molecule, and that the ruthenium coordination is distorted octahedral. Complex 2 is active in the metathesis of internal alkenes.

Synthesis and Properties in Solution of Rodlike, 2,2‘:6‘,2‘ ‘-Terpyridine-Based Ruthenium(II) Coordination Polymers

Rodlike ruthenium(II) coordination polymers have been prepared via the conversion of 4,4‘ ‘-bis(2,2‘:6‘,2‘ ‘-terpyridine)-2‘,5‘-dihexyl-p-terphenyl and an appropriately reactive ruthenium(III) species in 1-butanol/DMA. The diamagnetic polymers readily dissolve in polar organic solvents, and their homogeneous constitution could thus be proven and their degrees of polycondensation could be estimated to be Pn ≥ 30, using 1H and 13C NMR spectroscopy. The Pd-catalyzed polycondensation of bis[4‘-(p-bromophenyl)-2,2‘:6‘,2‘ ‘-terpyridine]ruthenium(II) tetrafluoroborate and 2,5-dihexylbenzene-1,4-diboronic acid, on the other hand, which should lead to a constitutionally identical polymer, only resulted in oligomers under all tested conditions. The intrinsic viscosity [η] of the high-molecular-weight polymers (determined in 0.02 M NH4PF6/DMA) is of the order of 300 mL g-1. In salt-free DMA solution and thus at low ionic strengths, the polymers display the characteristic polyelectrolyte behavior in viscosity experim...

Some new chain-like terdentate phosphines, their ruthenium(II) coordination chemistry and the activity of the cations [Ru(MeCN) 3(PhP{CH 2CH 2P( p-X-C 6H 4) 2} 2)] 2+ (X=H, F, Me and OMe) as acetalization catalysts

The new chain-like tritertiary phosphines PhP{CH 2CH 2P( p-X-C 6H 4) 2} 2, (X=F, Me and OMe), phetpX, were prepared and characterized. These ligands react with cis-[RuCl 2(DMSO) 4] giving equilibrium mixtures of the eclipsed ( ec) and staggered ( st) isomers of the dinuclear complexes [Ru 2(μ-Cl) 3(phetpX) 2]Cl. The preparation and characterization of the tritertiary phosphines MesP{CH 2CH 2P( p-X-C 6H 4) 2} 2 (Mes=mesityl, X=H and F), mesetpX, is also reported. They react with cis-[RuCl 2(DMSO) 4] giving equilibrium mixtures of corresponding uninuclear, [RuCl 2(mesetpX)], and dinuclear species, st-[Ru 2(μ-Cl) 3(mesetpX) 2]Cl, whose molecularities were established by determining their diffusion coefficients. The dissociation of st-[Ru 2(μ-Cl) 3(mesetph) 2]Cl to [RuCl 2(mesetph)] ( K=1.8×10 −2 mol −1) is endothermic (Δ H=32 kJ mol −1) and favored by entropy (Δ S=75 J mol −1). The complexes ‘RuCl 2(pp 2)’ (pp 2=phetph, and mesetph) react with CO giving fac-[RuCl 2(CO)(pp 2)] and fac-[RuCl(CO) 2(pp 2)]Cl as kinetic products. These complexes slowly rearrange to the thermodynamically stable products mer-[RuCl 2(CO)(pp 2)]. The complexes st-[Ru 2(μ-Cl) 3(phetpX) 2]Cl react with four equivalents of AgCF 3SO 3 in MeCN giving the corresponding salts [Ru(MeCN) 3(phetpX)](CF 3SO 3) 2. Their activities as catalysts for the acetalization of cyclo-hexanone with 1,2-dihydroxyethane and the trans-acetalization of cyclo-hexanone with 2,2-dimethyl-1,3-dioxolane are described.

Rod-like ruthenium(II) coordination polymers: synthesis and properties in solution

Download options Please wait... Article information DOI https://doi.org/10.1039/A901638D Article type Paper Download Citation Chem. Commun., 1999, 1123-1124 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Rod-like ruthenium(II) coordination polymers: synthesis and properties in solution S. Kelch and M. Rehahn, Chem. Commun., 1999, 1123 DOI: 10.1039/A901638D To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Steffen Kelch Matthias Rehahn

Soluble Ruthenium(II) Coordination Polymers Bearing Bulky Side Groups

Ruthenium(II) coordination polymers bearing lateral methyl and adamantylmethylene substituents, respectively, have been prepared via reaction of equimolar amounts of tetrapyridophenazine 2 and the novel metal monomers [Ru(R2bpy)Cl3]x (3a,b) (R: a, methyl; b, adamantylmethylene). Moreover, the bulky adamantylmethylene substituents are shown to cause a significantly more extended chain conformation of the intrinsically rigid, ribbon-like coordination polymers 1 than is found for other polymers of this kind available so far.

Synthesis of a New Multidentate Phosphane Ligand C6H2(CH2PPh2)4-1,2,4,5 − X-ray Structure of a Dinuclear Ruthenium(II)-Bridged Complex: [{RuCl2(PPh3)}2{C6H2(CH2PPh2)4-1,2,4,5-P,P′,P′′,P′′′}

The tetrakis(phosphane oxide) C6H2{CH2P(O)Ph2}4-1,2,4,5 (5), has been prepared in high yield from the Arbuzov reaction of C6H2(CH2Br)4-1,2,4,5 (4), with excess (7 equiv.) of Ph2POEt. Subsequent reduction of 5 with HSiCl3 (12 equiv.) in C6H4Cl2-1,2 afforded the new tetraphosphane C6H2(CH2PPh2)4-1,2,4,5 (6), in high yield. The reaction of 6 with [RuCl2(PPh3)4] in CH2Cl2 afforded the green dinuclear ruthenium(II) coordination complex [{RuCl2(PPh3)}2{C6H2- (CH2PPh2)4-1,2,4,5-P,P′,P′′,P′′′}]·0.5 CH2Cl2 (8), in 39% isolated yield. The solid-state molecular geometry of 8, determined by X-ray analysis, shows that the tetraphosphane is ortho-P,P′-chelated to each of the two [RuIICl2(PPh3)] units.

Comparative nephrotoxicity of some antitumour‐active platinum and ruthenium complexes in rats

The nephrotoxicity of three platinum (CPL, KP734, KP735) and three ruthenium coordination complexes (KP418, KP692, KP1019) was tested in rats in comparison to cisplatin (CP). Renal functional changes (excretion of water, protein, p-aminohippurate (PAH) and osmolytes) were not observed after the administration of 10% of the LD50 of the compounds given twice a week for up to 5 weeks. After a relatively high single dose of the substances (50% of the LD50), signs of nephrotoxicity on the day of maximal renal damage decreased in the following order: CP, KP418, CPL, KP734, KP735, KP692 and KP1019. In comparison to CP, proteinuria was significantly lower after the administration of any of the compounds, especially KP692 and KP1019. Neither renal lipid peroxidation (TBARS) nor glutathion status (GSH, GSSG) was affected. In summary, KP735 in the group of platinum complexes and KP1019 in the ruthenium group had the lowest nephrotoxicity. Other investigators have shown that all complexes induced anti-neoplastic activity under analogous experimental conditions. © 1998 John Wiley & Sons, Ltd.

Unusual properties of ruthenium(II) diphenylcyanamide complexes: chemistry and application as sensitizers of nanocrystalline TiO2

In this study, a series of ruthenium(II) polypyridyl complexes of the general formula Na4[RuII(dcbpy)2X2] (dcbpy is 2,2′-bipyridine-4,4′-dicarboxylate and X is a substituted phenylcyanamide anion) are investigated. When introduced into the ruthenium co-ordination sphere, the phenylcyanamide ligand showed linkage isomerism and was co-ordinated via the nitrile- or amide nitrogen, as shown by 1H NMR, 13C NMR spectroscopy and use of a 13C-labeled ligand. The title compounds exhibited unusually high first pKa values between 5 and 6, determined via spectrophotometric titrations. The first protonation occurred at the phenylcyanamide ligand, rendering the energy of the lowest energy 1MLCT absorption strongly pH-dependent. In photovoltaic devices, overall efficiencies were in the range of 3–4%, due to photon-to-current conversion efficiencies of 50–60% at 520 nm. The long-term stability of a representative complex under irradiation was investigated in solution and in a solar cell device.

High-Molecular-Weight Ruthenium(II) Coordination Polymers: Synthesis and Solution Properties

A synthetic strategy is presented that allows the preparation of high-molecular-weight ruthenium(II) coordination polymers 1a,b of homogeneous molecular constitution. The key to this success was the development of an efficient procedure leading to highly pure “metal monomers” [Ru(R2bpy)Cl3]x (3a,b) with (b: R = C6H5) and without (a: R = H) lateral phenyl substituents. Their conversion with equimolar quantities of “ligand monomer” tetrapyrido[3,2-a:2‘,3‘-c:3‘‘,2‘‘-h:2‘‘‘,3‘‘‘-j]phenazine (2) gave excellently soluble ruthenium(II) coordination polymers 1a and 1b, respectively, the molecular constitution of which was proven with high-resolution 1H and 13C NMR spectroscopy. The degrees of polymerization were estimated to be Pn ≥ 30 because of the complete lack of end group absorptions in the NMR spectra. This estimate could be verified by small-angle X-ray scattering (SAXS) for the phenyl-substituted polymer 1b: according to these investigations, the molecular weight reaches Mw ≈ 47 000, and the radius of ...

Air-stable ruthenium(II) and osmium(II) fluoride complexes. Crystal structures of [OC-6-13][MF2(CO)2(PR3)2] [M = Ru, PR3 = PEtPh2; M = Os, PR3 = PPh3 or P(C6H11)3

The reaction of Lewis bases L with [{MF2(CO)3}4] (M = Ru or Os) in organic solvents provided a clean, high-yield, route to a series of air- and moisture-stable ruthenium(II) and osmium(II) fluoride co-ordination compounds of general formulae [MF2(CO)2L2]. Characterisation by elemental analysis, FAB mass spectrometry, NMR and IR spectroscopy indicated a cis,cis,trans ligand arrangement. The crystal structures of [OC-6-13][MF2(CO)2(PR3)2] [M = Ru, PR3 = PEtPh2; M = Os, PR3 = PPh3 or P(C6H11)3] have been determined by X-ray crystallography. The geometry about the central metal atoms for all three structures is distorted pseudo-octahedral with ligand environments consistent with the spectroscopic data. In all the structures the phosphine ligands are bent towards the fluoride ligands and show intramolecular H · · · F interactions.

Electrospray ionization of divalent transition metal ion bipyridine complexes: spectroscopic evidence for preparation of solution analogs in the gas phase

Laser photofragmentation mass spectrometry provides the first spectroscopic evidence that electrospray ionization (ESI) produces gas-phase clusters containing transition metal ion complexes analogous to those found in solution. In solution, the tris(2,2′-bipyridyl)iron(II) and ruthenium(II) coordination complexes exhibit strong metal-to-ligand charge transfer (MLCT) absorption bands in the visible. The characteristic MLCT absorption bands are intact in gas-phase methanolic clusters containing these complexes, indicating that the metal oxidation state is preserved during ESI. Comparison of the ionic species produced by ESI and other ionization/volatilization techniques offers some insight on stabilization of the +2 charge in these gas-phase systems.

A Novel Synthetic Strategy toward Soluble, Well-Defined Ruthenium(II) Coordination Polymers

A Novel Synthetic Strategy toward Soluble, Well-Defined Ruthenium(II) Coordination Polymers

Synthetic methodologies for tripodal phosphines. The preparation of MeSi(CH 2PPh 2) 3 and n-BuSn(CH 2PPh 2) 3 and a comparison of their rhodium(I) and ruthenium(II) coordination chemistry. The X-ray crystal structures of [Rh(NBD){n-BuSn(CH 2PPh 2) 3}](OTf) and [Rh(NBD){MeSi(CH 2PPh 2) 3}](OTf)

The preparation of the new tripodal ligands MeSi(CH 2PPh 2) 3 (Si-triphos) and n-BuSn(CH 2PPh 2) 3 (Sn-triphos) and their complexes of rhodium(I) of the type [Rh(NBD)(tripod)](OTf) (NBD  norbornadiene, OTf  triflate) and of ruthenium(II) of the type [Ru(O 2CCF 3) 2(tripod)], is reported. The coordination chemistry of the new tripodal phosphines, and in particular that of Sn-triphos, differs significantly from that of MeC(CH 2PPh 2) 3 (triphos). A comparison of the X-ray structure of [Rh(NBD)(triphos)](OTf) with those of the new complexes [Rh(NBD)(Sn-triphos)](OTf) and [Rh(NBD)(Si-triphos)](OTf) shows that the steric requirements of the ligands RE(CH 2PPh 2) 3 (E  C, Si and Sn), increas from the carbon to the tin compound. The coordination chemistry of ruthenium(II) indicates that, relative to triphos, Sn-triphos displays an enhanced steric bulk which, however, is not sufficient to stabilize the mononuclear, five-coordinate dichloro complexes.