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A series of four new, cyclometallated ruthenium (II) complexes was synthesized from 3-acetyl-8-methoxy-2H-chromen-2-one functionalized 4( N )- substituted thiosemicarbazones and characterized through various spectral and analytical methods. The molecular structures of the complexes 1 , 2 and 4 were determined by single-crystal X-ray diffraction analysis, which confirmed that the complexes possess a distorted octahedral geometry with the ligands coordinating in a dibasic tridentate fashion via C, N and S atoms. DNA [Calf Thymus DNA (CT-DNA)] and protein [Bovine Serum Albumin (BSA) and Human Serum Albumin (HSA)] binding studies indicated an intercalative mode of binding with DNA and static quenching mechanism with proteins. The compounds cleaved plasmid DNA (pBR322) without application of any external agent and acted well as free radical scavengers. A good spectrum of antimicrobial activity was observed against four bacterial and five fungal pathogens. Two cancerous cell lines, MCF-7 (human breast cancer) and A549 (human lung carcinoma) were employed to test their in vitro cytotoxic activity using MTT assay. The complexes ( 1–4 ) showed better activity with lower IC 50 values over cisplatin . Further non toxic nature of the complexes have been examined with human normal keratinocyte cell line HaCaT. Further, the results of Lactate dehydrogenase release (LDH) and Nitric Oxide (NO) release supported the cytotoxic nature of the compounds. The results of all the biological studies carried out implied that the complex 3 bearing an ethyl substituent was observed to be the best. [ABSTRACT FROM AUTHOR]

Abstract: A series of p-cymene ruthenium dichloro complexes containing isonicotinic ester ligands, [(arene)RuCl2NC5H4-4-COO–C6H4–p-O-(CH2) n -CH3] (n = 1: 1, n = 3: 2, n = 5: 3, n = 7: 4, n = 9: 5, n = 11: 6, n = 13: 7, n = 15: 8), were prepared from p-cymene ruthenium dichloro dimer and the corresponding isonicotinic ester ligand. The single-crystal X-ray analysis of 1 shows the molecule to adopt the usual pseudo-tetrahedral piano-stool geometry, the isonicotinic ester ligand being coordinated through the nitrogen atom. The cytotoxicity of all complexes and of the free ligands was studied towards human ovarian cancer cells; high activities were observed only for n = 9 (presenting a chain with ten carbon atoms), both as far as the free ligands and the complexes are concerned. Based on this result, a new isonicotinic ester ligand with a C10 substituent containing a terminal alcohol function, NC5H4-4-COO–C6H4–p-O–(CH2)10–OH, was synthesized by a four-step method, and arene ruthenium complexes thereof, [(arene)RuCl2NC5H4-4-COO–C6H4–p-O–(CH2)10–OH] (arene = C6H6: 9a, arene = p-MeC6H4Pr i : 9b, arene = C6Me6: 9c) were prepared. The complexes 9a and 9b show indeed remarkable anticancer activities, the IC50 values for human ovarian cancer cells being in the submicromolar range. The highest cytotoxicity was observed for complex 9b, with IC50 values of 0.18 μM for A2780 and 3.04 μM for the cisplatin-resistant mutant A2780cisR. [Copyright &y& Elsevier]

Abstract: New ruthenium(II) complexes containing η6-arene-η1-pyrazole ligands were synthesized and characterized by elemental analysis and spectroscopic methods. In addition, the molecular structure of dichloro-3,5-dimethyl-1-(pentamethylbenzyl)-pyrazole–ruthenium(II), [Ru]L3b , was determined by X-ray diffraction studies. These complexes were applied in the transfer hydrogenation of acetophenone by isopropanol in the presence of potassium hydroxide. The activities of the catalysts were monitored by NMR. [Copyright &y& Elsevier]

The synthesis and characterization of complexes [(η-arene)Ru(N,N′)X][PF], where arene is para-cymene ( p-cym), biphenyl (bip), ethyl benzoate (etb), hexamethylbenzene (hmb), indane (ind) or 1,2,3,4-tetrahydronaphthalene (thn), N,N′ is 2,2′-bipyrimidine (bpm) and X is Cl, Br or I, are reported, including the X-ray crystal structures of [(η- p-cym)Ru(bpm)I][PF], [(η-bip)Ru(bpm)Cl][PF], [(η-bip)Ru(bpm)I][PF] and [(η-etb)Ru(bpm)Cl][PF]. Complexes in which N,N′ is 1,10-phenanthroline (phen), 1,10-phenanthroline-5,6-dione or 4,7-diphenyl-1,10-phenanthroline (bathophen) were studied for comparison. The Ru arene complexes undergo ligand-exchange reactions in aqueous solution at 310 K; their half-lives for hydrolysis range from 14 to 715 min. Density functional theory calculations on [(η- p-cym)Ru(bpm)Cl][PF], [(η- p-cym)Ru(bpm)Br][PF], [(η- p-cym)Ru(bpm)I][PF], [(η-bip)Ru(bpm)Cl][PF], [(η-bip)Ru(bpm)Br][PF] and [(η-bip)Ru(bpm)I][PF] suggest that aquation occurs via an associative pathway and that the reaction is thermodynamically favourable when the leaving ligand is I > Br ≈ Cl. p K* values for the aqua adducts of the complexes range from 6.9 to 7.32. A binding preference for 9-ethylguanine (9-EtG) compared with 9-ethyladenine (9-EtA) was observed for [(η- p-cym)Ru(bpm)Cl][PF], [(η-hmb)Ru(bpm)Cl], [(η-ind)Ru(bpm)Cl], [(η-thn)Ru(bpm)Cl], [(η- p-cym)Ru(phen)Cl] and [(η- p-cym)Ru(bathophen)Cl] in aqueous solution at 310 K. The X-ray crystal structure of the guanine complex [(η- p-cym)Ru(bpm)(9-EtG- N7)][PF] shows multiple hydrogen bonding. Density functional theory calculations show that the 9-EtG adducts of all complexes are thermodynamically preferred compared with those of 9-EtA. However, the bmp complexes are inactive towards A2780 human ovarian cancer cells. Calf thymus DNA interactions for [(η- p-cym)Ru(bpm)Cl][PF] and [(η- p-cym)Ru(phen)Cl][PF] consist of weak coordinative, intercalative and monofunctional coordination. Binding to biomolecules such as glutathione may play a role in deactivating the bpm complexes. [ABSTRACT FROM AUTHOR]

Abstract: A series of heterobimetallic complexes have been prepared by π-coordination of the [CpRu]+ fragment to the aromatic ring of POCOP pincer complexes of nickel, palladium and platinum. Their molecular structures were unequivocally determined by single-crystal X-ray diffraction, exhibiting the ruthenium moiety and the POCOP aromatic ring forming sandwich like species. The analysis in the solid state and in solution clearly showed that the coordination occurs in an orthogonal fashion and, as a consequence, both faces of the pincer complexes become non equivalent, thus conferring diastereotopicity to the isopropyl substituents. The electrochemical behavior of the new bimetallic complexes was studied and compared with that of the monometallic POCOP pincer precursors. [Copyright &y& Elsevier]

Abstract: A series of ruthenium(II) complexes bearing hydroxypicolinato ligands was synthesized and characterized. The reaction of [Ru(NNN)(pic-6OH)Cl] (1), where NNN is 2,6-bis(dimethylamino)methylpyridine and featuring the 6-hydroxypicolinate ligand (pic-6OH), with KOtBu in acetonitrile produced [Ru(NNN)(CH3CN)(2-pyridonato)] (4), in which pic-6OH was converted into its pyridonato tautomer form. The pyridonato-ligated complex 4 reacts with HCl to quantitatively regenerate 1, thus the interconversion between the pyridinol and pyridonato forms of hydroxypicolinate was successfully achieved using a Ru(II) complex supported by the NNN-pincer ligand. The complexes [Ru(NNN)(pic-3OH)Cl] (2) and [Ru(NNN)(pic)Cl] (3) were also prepared and characterized for comparison. [Copyright &y& Elsevier]

Abstract: The tetradentate N,N-bis(diphenylphosphanyl)amine ligand (Ph2P)2NCH2C6H4CH2N(PPh2)2 (1, xdppa) reacted with in situ prepared [Ru2(μ-H)(μ-PBu t 2)(PBu t 2H)2(CO)4] (2) in a molar ratio of 1:2 affording the novel twofold coordinatively unsaturated tetranuclear metal complex [Ru2(μ-H)(μ-PBu t 2)(CO)4(μ-xdppa)Ru2(μ-H)(μ-PBu t 2)(CO)4] (3). Compound 3 was protonated by tetrafluoroboric acid at each side of the unsaturated diruthenium frameworks affording the oxidative addition product [Ru2(μ-H)2(μ-PBu t 2)(CO)4(μ-xdppa)Ru2(μ-H)2(μ-PBu t 2)(CO)4](BF4)2 (4). All new compounds were characterized by spectroscopic means and the molecular structures of compounds 1 and 4 were determined by X-ray diffraction. [Copyright &y& Elsevier]

A series of cationic dinuclear p-cymene ruthenium trithiophenolato complexes of the type [(η- p-MeCHPr)Ru(SCH- p-X)] ( 1 X is H, 2 X is Me, 3 X is Ph, 4 X is Br, 5 X is OH, 6 X is NO, 7 X is OMe, 8 X is CF, 9 X is F, 10 X is Pr, 11 X is Bu) have been synthesized from the reaction of [(η- p-MeCHPr)RuCl] with the corresponding thiol, isolated as the chloride salts, and further studied for their electrochemical properties, cytotoxicity towards human ovarian cancer cells, and catalytic activity for glutathione (GSH) oxidation. Complex 1 was also compared with the benzene and hexamethylbenzene analogues [(η-CH)Ru(SCH)] ( 12) and [(η-CMe)Ru(SCH)] ( 13). The most active compound [ 11]Cl was structurally studied by single-crystal X-ray diffraction analysis. The concentrations corresponding to 50 % inhibition of cancer cell growth (IC values) in the A2780 and A2780cisR cell lines of these complexes except for 6 were in the submicromolar range, complex 11 showing an IC value of 0.03 µM in both cell lines. The high in vitro anticancer activity of these complexes may be at least partially due to their catalytic potential for the oxidation of GSH, although there is no clear correlation between the IC values and the turnover frequencies at about 50 % conversion. However, the cytotoxicity is tentatively correlated to the physicochemical properties of the compounds determined by the electronic influence of the substituents X (Hammett constants σ) and the lipophilicity of the thiols p-XCHSH (calculated log P parameters). [ABSTRACT FROM AUTHOR]

Three complexes [Ru(CN)4(HAT)]2-(HAT = hexaazatriphenylene; [Ru1]2-), [{Ru(CN)4}2 (μ2-HAT)]4-([RU2]4-) and [{RU(CN)4}3(μ3-HAT)]6-([RU3]6-) for supramolecular assemblies are investigated by quantum-chemical calculations. Due to symmetry of complexes, the energy level differences are 2.014eV and 2.019eV for [Ru1]2- and [Ru3]6- complex, which are about 0.4 eV larger than that for [Ru3]2- complex. The absorption maximum for [Ru3]2- complex in water is at 375.8 nm. Coordination of the second and third Ru(II) center to produce [Ru2]4- and [Ru3]6- result in a red-shift of this strongest absorption to 453.4 nm and 468.1 nm, respectively. Absorption maximum of three complexes belong to MLCT transitions, which are revealed by frontier molecular orbital theory and charge difference density method. [ABSTRACT FROM AUTHOR]

Abstract: Two benzoylpyrazine ligands containing carboxyl and amide functions and their hydride-carbonyl complexes of ruthenium were synthesized and characterized by infrared, proton, carbon phosphorus nuclear magnetic resonance, electronic absorption and emission spectroscopy and X-ray crystallography. The experimental studies were completed by theoretical calculations. From the electronic spectrum of the complex the Racah’s and nepheloauxetic parameters are calculated. The electronic structure of the complexes, presented in particular by the density of states diagram, have been correlated with its ability to fluoresce and used to analyze the UV–Vis spectra. [Copyright &y& Elsevier]

Reaction of (S)-1-(2-chlorophenyl)ethanolwith[Cp*Ru(CH3CN)3][OTf] provides the single diastereomer(Sp)-[Cp*Ru(η6-(S)-1-(2-chlorophenyl)ethanol)][OTf] ((Sp,S)-1), in which the metal center is preferentiallyplaced on one side of the arene ring. The other enantiomer (R)-1-(2-chlorophenyl)ethanol provides the planar chiralruthenium compound (Rp,R)-1. The structures of both enantiomers were ascertained bysingle-crystal X-ray diffraction. These compounds can be used as precursorsto prepare the enantiopure metalated phosphino ligands (Sp)-[Cp*Ru(η6-(S)-1-(2-diphenylphosphinophenyl)ethanol)][OTf]((Sp,S)-2) and (Rp)-[Cp*Ru(η6-(R)-1-(2-diphenylphosphinophenyl)ethanol)][OTf]((Rp,R)-2), in whichthe −PPh2unit is attached to a chiral metalatedπ-arene platform. The chiral planar phosphine ligands reactwith [AuCl(tht)] to give heterobinuclear gold complexes with planarchirality, [AuCl((Sp,S)-2)] ((Sp,S)-3) and[AuCl((Rp,R)-2)] ((Rp,R)-3), as confirmed bytheir CD traces. Our method provides an entry to the preparation ofa wide range of optically pure coordination compounds with potentiallyimportant properties. [ABSTRACT FROM AUTHOR]

Three series of heterodinuclear ruthenium–ironcomplexeshave been synthesized from (η6-arene)ruthenium dichloridedimers and phosphinoferrocene ligands containing glycine-based carboxamidosubstituents. The neutral complexes [(η6-arene)RuCl2(Ph2PfcCONHCH2CO2Me-κP)] (4, arene = benzene (a), p-cymene (b), hexamethylbenzene (c); fc = ferrocene-1,1′-diyl) were obtained by the bridge cleavagereaction of [(η6-arene)RuCl2]2with Ph2PfcCONHCH2CO2Me (1) in chloroform solution. The complex [(η6-p-cymene)RuCl2(Ph2PfcCONHCH2CONH2-κP)] (6b) was synthesized in the same way from Ph2PfcCONHCH2CONH2(3); the preparation of [(η6-p-cymene)RuCl2(Ph2PfcCONHCH2CO2H-κP)](5b), featuring the ferrocene ligand in the free acidform (2), failed due to side reactions and isolationproblems. The salts [(η6-arene)RuCl(MeCN)(1-κP)][PF6] (7a–c) and [(η6-arene)Ru(MeCN)2(1-κP)][PF6]2(8a–c) were prepared from 1and the acetonitrile precursors [(η6-arene)RuCl(MeCN)2][PF6] and from 4a–cvia halide removal with Ag[PF6] in acetonitrile solution,respectively. Alternative synthetic routes to 7band 8bwere also studied. The compounds were fully characterizedby elemental analysis, multinuclear NMR, IR, and electrospray ionizationmass spectra, and their electrochemical properties were studied bycyclic voltammetry at a Pt-disk electrode. The single-crystal X-rayanalyses of two representatives (4band 8b) revealed a pseudotetrahedral coordination geometry at the rutheniumcenters and eclipsed conformations of the ferrocene moieties, withthe substituents at the two cyclopentadienyl rings being anti withrespect to each other. All complexes showed high activity for thecatalytic oxidation of secondary alcohols with tert-butyl hydroperoxide to give ketones in aqueous media. The most activecatalyst was obtained from the neutral p-cymene complex 4b, showing a catalytic turnover frequency of 13 200h–1at room temperature for the oxidation of 1-phenylethanolat a substrate/catalyst ratio of 100 000. [ABSTRACT FROM AUTHOR]

Abstract: We report the synthesis of trans-dichlorobis(1,3-diaminopropane)ruthenium(III) chloride. The molecular structure consists of a ruthenium metal complex and a chloride counterion. Electronic spectra of the solid complexes indicate an octahedral geometry around the ruthenium(III) metal center. We observe a UV-broadened band at 350nm, a common absorption band in trans-ruthenium(III) amine and haloamine complexes. We also report, the single-crystal X-ray structures of the titled complex. The complex was shown to form a self assembled monolayer on quartz, which is a suitable substrate for deposition of conducting polymer PANI, PEDOT and PPy. We discuss key parameters which can be adjusted to tune both the physical properties of the Ru(III) surfaces and the sheet conductivity of the deposited conducting polymers thin films. [Copyright &y& Elsevier]

Abstract: A dearomatized complex [RuH(PN3P)(CO)] (PN3P N, N′-bis(di-tert-butylphosphino)-2,6-diaminopyridine) (3) was prepared by reaction of the aromatic complex [RuH(Cl)(PN3P)(CO)] (2) with t-BuOK in THF. Further treatment of 3 with formic acid led to the formation of a rearomatized complex (4). These new complexes were fully characterized and the molecular structure of complex 4 was further confirmed by X-ray crystallography. In complex 4, a distorted square-pyramidal geometry around the ruthenium center was observed, with the CO ligand trans to the pyridinic nitrogen atom and the hydride located in the apical position. The dearomatized complex 3 displays efficient catalytic activity for hydrogen transfer of ketones in isopropanol. [Copyright &y& Elsevier]

Abstract: Organometallic ruthenium complexes containing two dehydrogenated maltol ligands Ru3(CO)8(2L–2H) 1, Ru3(CO)7PPh3(2L–2H) 2, [Ru3(CO)7 (2L–2H)]2(dppm or dppe) 3,4 (L = Maltol) have been synthesized and characterized. The in vitro anticancer activity of compounds 1–4 against seven types of human cancer cell lines was assessed and compared to clinically used drug cisplatin. The anticancer activity of compound 1 () is many times more potent than cisplatin against seven types of human cancer cell lines. There is a correlation between substituting a CO ligand in 1 with different phosphines decreases the activity following the order 1 > 2 > 3 > 4. The X-ray crystal structures of complexes 1 and 2 are reported. The single crystal X-ray diffraction structure of 1 consists of a triangular ruthenium metal framework in which a Ru–Ru bond is bridged by two maltolate ligands with their two oxygen atoms in a μ−η 2-bonding mode. The dihedral angle between Ru3 and maltol planes is 40.2°. The two ruthenium atoms bridged by maltol ligands each have two carbonyl ligands and the third ruthenium atom is bonded to four carbonyl ligands. The greatest structural difference between 1 and 2 is the angle between the best planes of the two coordinated C6H5O3 −1 ligands; in 1 it is 27.1° while in 2 it is 42.8°. It is interesting to note that the phosphine substitution occurs at the ruthenium atom not bound by maltol ligands. [Copyright &y& Elsevier]

Abstract: The reaction of [RuX3(AsPh3)3] and N,N-disubstituted pyridazine-3,6-diamine in benzene under reflux afford novel binuclear, halo-bridged, ruthenium(III) complexes with the general formula [Ru2(AsPh3)2(μ-X)2X4(L)] (X=Cl or Br; L= N,N-disubstituted pyridazine-3,6-diamine). All the complexes have been characterized by elemental analysis, spectral (UV–Vis, EPR) and electrochemical methods (CV, DPV). The electronic spectra of the complexes indicate the presence of d–d and intense LMCT transitions in the visible region. The molecular structure of one of the complexes (2) has been determined by X-ray crystallography, which indicates the bridging coordination of the pyridazine in these binuclear complexes. In complex (2) each metal has a distorted octahedral NCl4As coordination sphere constituted by the two exogenous bridging chlorides. The complexes are paramagnetic (low spin, d 5) in nature and all the complexes at 77K show rhombic distortion around the ruthenium ion with three different ‘g’ values (gx ≠ gy ≠ gz ). All the complexes exhibit two quasi-reversible one electron reductive responses (RuIII–RuIII/RuII–RuIII; RuII–RuIII/RuII–RuII) within the E 1/2 range of −0.68 to −0.78V and −1.25 to −1.33V, respectively, versus SCE. [Copyright &y& Elsevier]

Abstract: The ruthenium(III) complexes [Ru(L n )2]ClO4 with 4-R-2-((2-(pyridin-2-yl)hydrazono)methyl)phenol (HL n ; R =H, Cl, Br, Me and OMe) have been synthesized. Microanalysis, magnetic susceptibility and various spectroscopic (IR, UV–Vis and EPR) measurements have been used for the characterization of these complexes. The molecular structures of all the complexes, except for the complex where R =Br, have been confirmed by a single crystal X-ray diffraction study. The metal centers in these complex cations are in a distorted octahedral N4O2 environment formed by the pyridine-N, the imine-N and the phenolate-O donor (L n )− ligands. Intermolecular hydrogen-bonding assisted supramolecular structures assembled by the solvated complexes range from dimeric to one-dimensional chain to two-dimensional sheet structures. [Copyright &y& Elsevier]

Bis(2,2′-bipyridine) complexes of ruthenium(II) with 2-, 3-, and 4-acetylpyridine derivatives were synthesized and structurally characterized. The effect of changing the location of the pyridine's acetyl substituent was studied experimentally and theoretically to clarify the effect of substituent position on the chemical behavior and photochemical properties of the complex. The substituent position on the heterocyclic-pyridine was found to strongly affect the chemical and photochemical properties of the complex. Variation of the position of the substituent, and thus ligand modification brought by as a consequence of this variation, offers possibilities to design complexes of desired structural and photochemical properties. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this Note is the study of the structure and fluxional behavior of the complex [{Ru(CO)2(η5C5H5)}3(η1:η1:η2:-CC)]+, using density functional methods. The molecular geometry of this complex will be optimized, the transition state (TS) of the fluxional process will be determined and the origin of the energy barrier will be analyzed. [Copyright &y& Elsevier]

The cyclopentadienyl-containing complex [Ru(η5-C5H5)(MeCN){κ3(P,C,C)-Ph2PCH2CHCH2}][PF6] (1) reacts with allenes, giving regioselectively the η2-allene complexes [Ru(η5-C5H5)(MeCN){κ(P)-Ph2PCH2CHCH2}(η2-CH2CCR1R2)][PF6] [R1= R2= Me (3); R1= H, R2= Ph (4); R1R2= −(CH2)5– (5)]. On the other hand, the reaction of the pentamethylcyclopentadienyl-containing complex [Ru(η5-C5Me5)(MeCN){κ3(P,C,C)-Ph2PCH2CHCH2}][OTf] (2) with allenes yields regio- and stereoselectively the complexes [Ru(η5-C5Me5){κ(P),η4-Ph2PCH2CHCHC(R1R2)CHCH2}][OTf] [R1= R2= Me (6); R1= H, R2= Ph (7); R1R2= −(CH2)5– (8)] via the intermolecular coupling of allene and allyldiphenylphosphine ligands. The intermediate complex [Ru(η5-C5Me5)(MeCN){κ(P)-Ph2PCH2CHCH2}{η2-CH2CCMe2}][OTf] (9) has been spectroscopically characterized. The structure of complex [Ru(η5-C5Me5){κ(P),η4-Ph2PCH2CHCHC(Me)2CHCH2}][{3,5-(CF3)2C6H3}4B] (6a) has been resolved by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Electron-rich PNP- and PNN-type ruthenium(II) hydrido borohydride pincer complexes, [RuH(BH4)(tBu-PNP)] (tBu-PNP = (2,6-bis(di-tert-butylphosphinomethyl)pyridine) (5) and [RuH(BH4)(tBu-PNN)] (tBu-PNN = 2-di-tert-butylphosphinomethyl-6-diethylaminomethylpyridine) (6), were prepared from their corresponding N2-bridged dinuclear Ru(II) complexes [(tBu-PNP)RuCl2]2(μ-N2) (3) and [(tBu-PNN)RuCl2]2(μ-N2) (4), respectively. The X-ray structure of 5reveals a BH4–anion η2coordinated to ruthenium through two bridging hydrides. A variable-temperature 1H NMR study of 6exhibits interesting fluxional behavior of the BH4–ligand. Similarly, the Ru(II) hydrido borohydride complex 9, in which the BH4–moiety is coordinated in a η1bonding mode, was obtained by reaction of [RuCl2(PPh3)(iPr-PNP)] (iPr-PNP = 2,6-bis(diisopropylphosphinomethyl)pyridine) (8) with two equivalents of NaBH4at room temperature. The hydrido borohydride pincer complexes 5, 6, and 9catalyze the acceptorless dehydrogenative coupling of primary alcohols to esters and the dehydrogenation of secondary alcohols to the corresponding ketones, accompanied by evolution of hydrogen gas. The reactivity follows the order 6> 9> 5. With the hydrido borohydride complex 6as catalyst, high yields (up to 98%) and high turnover numbers (TON ∼1000) were obtained in the dehydrogenation of primary alcohols under mild and neutral conditions. In addition, 6effectively catalyzes the hydrogenation of nonactivated aromatic and aliphatic esters to the corresponding alcohols with TON ∼200 under a relatively mild pressure of dihydrogen and neutral and homogeneous conditions. Thus, an efficient homogeneous catalytic system for the dehydrogenation–hydrogenation reactions of alcohols is developed, which is relevant to the current interest in hydrogen storage. [ABSTRACT FROM AUTHOR]

The complexation of di-(2-pyridylmethyl)amine to RuHCl(PPh3)3affords the salt [RuH{κ3N-fac-1,3-di-(2-pyridylmethyl)amine}(PPh3)2]Cl. Reaction with potassium tert-butoxide at room temperature yields the unusual ruthenaziridine complex RuH{κ3CalkNNpy-1,3-di-(2-pyridylmethyl)amine}(PPh3)2, where the central nitrogen atom, adjacent alkyl carbon, and pyridine arm coordinate to the metal, leaving the second pyridine arm uncoordinated. Surprisingly, heating of this ruthenaziridine complex with concomitant H2formation affords the ruthenium azaallyl complex RuH(κ3N-1,3-di-(2-pyridyl)-2-azaallyl)(PPh3)2. This is a rare example of a 4d metal complex containing the azaallyl ligand. X-Ray crystal structures and NMR characterization of all three compounds are presented herein. [ABSTRACT FROM AUTHOR]

The S‒S bond undergoes a reductive cleavage when 2,2′-dithiobis(5-nitropyridine) is reacted with Ru(bpy)2Cl2 (bpy = 2,2′-bipyridine) and yields the monocationic species [Ru(bpy)2(S-Py-NO2)]+. The synthesized complex Ru(N5S)+ was characterized by UV-visible (UV-Vis), cyclic voltammetry, FT-IR, 1H-NMR, and X-ray. The 1H-NMR spectra show a set of signals according to low complex symmetry. The electrochemistry analysis showed a quasi-reversible RuIII/II wave observed at 0.78 V versus Ag/AgCl. X-ray structural analysis revealed a distorted octahedral coordination sphere around the metal. The octahedral N5S chromophore surrounding the metal ion is formed via two trans N and S atoms and four nitrogen atoms from two bis(2,2′-bipyridiyl) ligands. The distortion provoked by an N,S-schelating short-bite ligand has already been shown in similar derivatives. In the title compound, this effect is more dramatic since the four-membered ring presents more strain, and this effect is similar to the previously analyzed four-membered N,S-chelating short-bite ligand. [ABSTRACT FROM AUTHOR]

The syntheses, structures, and reactivities of diruthenium complexes having a five-, six-, and seven-membered cyclic diene ligands are discussed in this paper. While the μ-η2:η2-cyclohexadiene complex 3was readily prepared by the reaction of the diruthenium tetrahydrido complex 1with 1,3-cyclohexadiene, 3was alternatively synthesized by the reaction of 1with benzene via partial hydrogenation of benzene on a diruthenium plane. While the μ-η2:η2-cyclohexadiene ligand was liberated as benzene upon mild heating, the treatment of 3with tBuNC and CO caused further migration of hydrido ligand to the C6moiety to yield the μ-η2-cyclohexenyl complex 6and the μ-cyclohexylidene complex 8, respectively. The reactions of 1with cyclopentadiene and cycloheptatriene also afforded the bridging cyclic diene complexes 10and 11. While the thermolysis of the μ-η2:η2-cyclopentadiene complex 10resulted in the degradation of the cluster skeleton forming Cp*RuCp (12), the μ-η2:η2-cycloheptadiene complex 11was stable upon heating. These differences can be attributed to the aromatization of the cyclic diene moiety. [ABSTRACT FROM AUTHOR]

Abstract: Reaction of thiophene-2-methylamine with one or two equivalents of PPh2Cl in the presence of NEt3, proceeds in thf to give thiophene-2-(N-diphenylphosphino)methylamine, 1a and thiophene-2-(N,N-bis(diphenylphosphino))methylamine, 2a respectively, under anaerobic conditions. Oxidations of 1a and 2a with aqueous hydrogen peroxide, elemental sulfur or gray selenium in thf gives the corresponding oxides, sulfides and selenides [Ph2P(E)NHCH2-C4H3S] (E: O 1b, S 1c, Se 1d) and [(Ph2P(E))2NCH2-C4H3S], (E: O 2b, S 2c, Se 2d) respectively, in high yield. Furthermore, two novel Ru(II) complexes with the P–N ligands 1a and 2a were synthesized starting with the complex [Ru(η6-p-cymene)(μ-Cl)Cl]2. The complexes were fully characterized by analytical and spectroscopic methods. 31P–{1H} NMR, DEPT, 1H–13C HETCOR or 1H–1H COSY correlation experiments were used to confirm the spectral assignments. The molecular structure of thiophene-2-(N-diphenylthiophosphino)methylamine was also elucidated by single-crystal X-ray crystallography. Following activation by NaOH, compounds 3 and 4 catalyze the transfer hydrogenation of acetophenone derivatives to 1-phenylethanol derivatives in the presence of iso-PrOH as the hydrogen source. [Ru(Ph2PNHCH2-C4H3S)(η6-p-cymene)Cl2], 3 and [Ru((PPh2)2NCH2-C4H3S)(η6-p-cymene)Cl]Cl, 4 complexes are suitable catalyst precursors for the transfer hydrogenation of acetophenone derivatives in 0.1M iso-PrOH solution. Notably 4 acts as an excellent catalyst giving the corresponding alcohols in excellent conversions up to 99% (TOF⩽744h−1). This transfer hydrogenation is characterized by low reversibility under the experimental conditions. [Copyright &y& Elsevier]

The structure and spectral properties of two organic ruthenium complexes used as sensitizing dyes for solar batteries (well-known N3 dye and its selenophene-conjugated analogue C105 ([Ru(bpy)(bpysef)(COOH)(NCS)] (bpy = 2,2′-bipyridine, bpysef = 4,4′-bis(5-hexylselenophene-2-yl)2,2′-bipyridine)) are comparatively studied within the density functional method. It is shown that the conjugation of the bipyridine ligand with selenophene affects the electronic structure of the C105 dye. A multilevel model for interpreting the electronic spectra of dyes is proposed based on the analysis of the shapes of molecular orbitals. The nature of the absorption bands of these ruthenium complexes in the region of 300-800 nm is explained. It is found that, in the polar acetonitrile solvent, these dyes are negatively solvatochromic, which agrees with the current classical views on the effect of the solvent on the shape of electronic absorption spectra of related compounds. [ABSTRACT FROM AUTHOR]

Abstract: [RuHCl(CO)(PPh3)2(py)], [RuHCl(CO)(PPh3)2(pyIm)] and [RuCl(CO)(PPh3)2(pyoh)]·2CH3OH complexes (where py=pyridine, pyIm=imidazo[1,2-α]pyridine, pyoh=2-hydroxy-6-methylpyridine) have been prepared and studied by IR, NMR, UV–Vis spectroscopy and X-ray crystallography. Electronic structures and bonding of the complexes were defined on the basis of DFT method, and the pyridine derivative ligands were compared on the basis of their donor–acceptor properties. Values of the ligand field parameter 10Dq and Racah’s parameters were estimated for the studied compounds, and the luminescence properties were determined. [ABSTRACT FROM AUTHOR]

Abstract: The Ru(II) precursors, [RuHCl(CO)(EPh3)3] (E=P or As) when reacted with some well known monoxime and dioxime ligands in ethanolic solution afforded the new complexes of the types [RuCl(CO)(EPh3)2L1], [RuH(CO)(EPh3)2L2] and [RuCl(CO)(EPh3)2L3] ((H1L1)=diacetylmonoxime, (H1L2)=dimethylglyoxime and (H2L3)=benzoiloxime). The ligands coordinated in a bidentate chelate mode forming a five membered chelate ring. The molecular structures of two of the complexes have been determined by single crystal X-ray diffraction study. The structural determination confirms the deprotonation of the oxime function. Examination of all the complexes by cyclic voltammetry showed the occurrence of some quasi-reversible redox reactions owing to changes in the oxidation state of the central metal atoms. Structural assignments are supported by combination of IR, UV–Vis, 1H NMR and elemental analyses. In addition, the DNA binding properties and cleavage efficiency of new complexes have been tested. [ABSTRACT FROM AUTHOR]

Abstract: Mononuclear ruthenium–thiolate complexes of structural type CpRu(PPh3)2SR (1) [R=2-imidazolyl (a), 1-methylimidazolyl (b), 5-methyl-1,3,5-thiadiazolyl (c) and 5-methyl-4H-1,2,4-triazolyl (d)] are accessible from the reaction of CpRu(PPh3)2Cl with the corresponding thiolate anions. Reaction of CpRu(PPh3)2Cl with the heterocyclic-thiolate anions in the presence of the bisphosphine ligands affords CpRu(P–P)SR [P–P=bis(diphenylphosphino)methane; dppm (2), bis(diphenylphosphino)ethane; dppe (3)]. If CO gas was bubbled through a THF solution of 1b, the complex CpRu(PPh3)(CO)S(C4N2H5) (4b) is produced. These ruthenium–heterocyclic thiolate complexes have been characterized by elemental analysis, spectroscopy (IR, 1H, 31P{1H} NMR and MS) and cyclic voltammetry for some samples. The solid-state structures of 3a and 3b are determined by single-crystal X-ray structure analysis. [ABSTRACT FROM AUTHOR]

Octahedral, trigonal prismatic, and capped square pyramidal structures have been optimized for the Ru6C(CO)nclusters (15 ≤ n≤ 20) using density functional theory. The experimentally known very stable Ru6C(CO)17is predicted to have an octahedral structure in accord with experiment as well as the Wade–Mingos rules. The stability of Ru6C(CO)17is indicated by its high carbonyl dissociation energy of ∼37 kcal mol−1and the high energy of ∼33 kcal mol−1required for disproportionation into Ru6C(CO)18+ Ru6C(CO)16. Theoretical calculations predict a doubly carbonyl bridged octahedral Ru6C(CO)17structure to be ∼0.7 kcal mol−1more stable than the experimentally observed singly bridged structure. A trigonal prismatic Ru6C(CO)19cluster isoelectronic with the known Co6C(CO)152−dianion does not appear to be viable as indicated by a low carbonyl dissociation energy of 8.8 kcal mol−1and a required energy of only 4.9 kcal mol−1for disproportionation into Ru6C(CO)20+ Ru6C(CO)18. The predicted instability of Ru6C(CO)n(n≥ 18) derivatives suggests a maximum of 17 external carbonyl groups around a stable polyhedral Ru6C structure. [ABSTRACT FROM AUTHOR]

Abstract: Reactions of 1-{[2-(arylazo)phenyl]iminomethyl}-2-phenol, HLsal, 1, [where H represents the dissociable protons upon complexation and aryl groups of HLsal are phenyl for HL1 sal, p-methylphenyl for HL2 sal, and p-chlorophenyl for HL3 sal], ligands with Ru(H)(CO)(Cl)(PPh3)3 afforded complexes of composition [(Lsal)Ru(CO)(Cl)(PPh3)] and (Lsal)2Ru where the N,N,O donor tridentate (Lsal)− ligands coordinated the metal centre facially and meridionally, respectively. Stepwise formation of [(Lsal)2Ru] has been ascertained. Reaction of 1-{[2-(arylazo)phenyl]iminomethyl}-2-napthol, HLnap, 2, [where H represents the dissociable protons upon complexation and aryl groups of HLnap are phenyl for HL1 nap, p-methylphenyl for HL2 nap, and p-chlorophenyl for HL3 nap], ligands with Ru(H)(CO)(Cl)(PPh3)3 afforded exclusively the complexes of composition [(Lnap)Ru(CO)(Cl)(PPh3)], where N,N,O donor tridentate (Lnap)− was facially coordinated. The ligand 1-{[2-(phenylazo)phenyl]aminomethyl}-2-phenol, HL, 3, was prepared by reducing the aldimine function of HL1 sal. Reaction of HL with Ru(PPh3)3Cl2 afforded new azosalen complex of Ru(III) in concert with regiospecific oxygenation of phenyl ring of HL. All the new ligands were characterized by analytical and spectroscopic techniques. The complexes were characterized by analytical and spectroscopic techniques and subsequently confirmed by the determination of X-ray structures of selected complexes. [ABSTRACT FROM AUTHOR]

Abstract: The ruthenium–nitrosyl complexes [RuII(trpy)(tmp)(NO+)](ClO4)3 ([4](ClO4)3) and [RuII(trpy)(tmp)(NO )](ClO4)2 ([5](ClO4)2) with {Ru–NO}6 and {Ru–NO}7 configurations, respectively (trpy=2,2′:6′,2′′-terpyridine, tmp=3,4,7,8-tetramethyl-1,10-phenanthroline) have been isotaled. The nitrosyl complexes [4]3+ and [5]2+ have been generated by following a stepwise synthetic procedure: [RuII(trpy)(tmp)(X)] n , X/n =Cl/+ (1 +)→CH3CN/2+ (2 2+)→NO2/+ (3 +)→NO+/3+ (4 3+)→NO /2+ (5 2+). The single-crystal X-ray structures of two precursor complexes [1]ClO4 and [3]ClO4 have been determined. The DFT optimized structures of 4 3+ and 5 2+ suggest that the Ru–N–O geometries in the complexes are linear (177.9°) and bent (141.4°), respectively. The nitrosyl complexes with linear (4 3+) and bent (5 2+) geometries exhibit ν(NO) frequencies at 1935cm−1 (DFT: 1993cm−1) and 1635cm−1 (DFT: 1684cm−1), respectively. Complex 4 3+ undergoes two successive reductions at 0.25V (reversible) and −0.48V (irreversible) versus SCE involving the redox active NO function, RuII–NO+ ⇄RuII–NO and RuII–NO →RuII–NO−, respectively, besides the reductions of trpy and tmp at more negative potentials. The DFT calculations on the optimized 4 3+ suggest that LUMO and LUMO+1 are dominated by NO+ based orbitals of around 65% contribution along with partial metal contribution of ∼25% due to (dπ)RuII →π∗(NO+) back-bonding. The lowest energy transitions in 4 3+ and 5 2+ at 360nm and 467nm in CH3CN (TD-DFT: 364 and 459nm) have been attributed to mixed MLLCT transitions of tmp(π)→NO+(π∗), Ru(dπ)/tmp(π)→NO+(π∗) and Ru(dπ)/NO (π)→trpy(π∗), respectively. The paramagnetic reduced species 5 2+ exhibits an anisotropic EPR spectrum with g 1 =2.018, g 2 =1.994, g 3 =1.880 (〈g〉=1.965 and Δg =0.138) in CH3CN, along with 14N (I=1) hyperfine coupling constant, A2=35G at 110K due to partial metal contribution in the singly occupied molecular orbital (DFT:SOMO:Ru (34%) and NO (53%)). Consequently, Mulliken spin distributions in 5 2+ are calculated as 0.115 for Ru and 0.855 for NO (N, 0.527; O, 0.328). The reaction of moderately electrophilic nitrosyl center in 4 3+ with the nucleophile, OH− yields the nitro precursor, 3 + with the second-order rate constant value of 1.7×10−1 M−1 s−1 at 298K in CH3CN–H2O (10:1). On exposure to light (Xenon 350W lamp) both the nitrosyl species, 4 3+ ({RuII–NO+}) and 5 2+ ({RuII–NO }) undergo photolytic Ru–NO bond cleavage process but with a widely varying k NO, s−1 (t 1/2, s) of 1.56×10−1(4.4) and 0.011×10−1(630), respectively. [Copyright &y& Elsevier]

Abstract: The previously reported complex [Ru(ttpy)(CN)3]− [ttpy=4′(p-tolyl)-2,2′:6′,2″-terpyridine] is conveniently synthesised by reaction of ttpy with Ru(dmso)4Cl2 to give [Ru(ttpy)(dmso)Cl2], which reacts in turn with KCN in aqueous ethanol to afford [Ru(ttpy)(CN)3]− which was isolated and crystallographically characterised as both its (PPN)+ and K+ salts. The K+ salt contains clusters containing three complex anions and three K+ cations connected by end-on and side-on cyanide ligation to the K+ ions. The solution speciation behaviour of [Ru(ttpy)(CN)3]− was investigated with both Zn2+ and K+ salts in MeCN, a solvent sufficiently non-competitive to allow the added metal cations to associate with the complex anion via the externally-directed cyanide lone pairs. UV–Vis spectroscopic titration of (PPN)[Ru(ttpy)(CN)3] with Zn(ClO4)2 showed a blue shift of 2900cm−1 in the 1MLCT absorption manifold due to the ‘metallochromism’ effect; a series of distinct binding events could be discerned corresponding to formation of 4:1, 1:1 and then 1:3 anion:cation adducts, all with high formation constants, as the titration proceeded. In contrast titration of (PPN)[Ru(ttpy)(CN)3] with the more weakly Lewis-acidic KPF6 resulted in a much smaller blue-shift of the 1MLCT absorptions, and the titration data corresponded to formation of 1:1 and then 2:1 cation:anion adducts with weaker stepwise association constants of the order of 104 and then 103 M−1. Although association of [Ru(ttpy)(CN)3]− resulted in a blue-shift of the 1MLCT absorptions, the luminescence was steadily quenched, as raising the 3MLCT level makes radiationless decay via a low-lying 3MC state possible. [Copyright &y& Elsevier]

Abstract: In an unusual reaction of H2L2 (H2L2 =N-heteropentacene) with Ru(PPh3)3Cl2 a phospho-ylide ruthenium(II) complex (1) was obtained via unprecedented chemical transformations of the conjugate base [L2]2−. A bidentated phospho-ylide ligand is formed with concomitant aromatic ring hydroxylation and new C–P bond formation reactions. The new ligand, binds to RuII as a neutral N, O-donor. Crystal structure determination by single crystal X-ray diffraction has been used to characterize the compound. The phospho-ylide Ru(II) description of the complex was established based on 13C as well as 31P NMR studies. The complex shows rich spectral and redox properties. UV–Vis–NIR spectrum consisted of multiple low-energy transitions in the visible and near IR regions. Preliminary density functional theory calculations were employed to understand the electronic structure and to assign the spectral transitions. Cyclic voltammogram and EPR-spectrum of the electrogenerated oxidized compound are reported and used to characterize the redox properties. [ABSTRACT FROM AUTHOR]

Abstract: Interaction of the dimer [(η 6-p-cymene)RuCl(μ-Cl)]2 or [Cp∗RuCl(μ-Cl)]2 with two equiv. of K[HB(timMe)3] at reflux gave anionic complex [(η 6-p-cymene)Ru{κ 3-S,S,S-HB(timMe)3}]Cl (1) or neutral complex [Cp∗Ru{κ 3-S,S,S-HB(timMe)3}] (2), respectively, with terminally non-coordinated Bomplexes 1 and 2 were further refluxed in CHCl3 to result in the quantitative formation of [(η 6-p-cymene)Ru{κ 3-S,S,S-ClB(timMe)3}]Cl (3) and [Cp∗Ru{κ 3-S,S,S-ClB(timMe)3}] (4), respectively, with B Treatment of [RuHCl(CO)(PPh3)3] or [Ru(PPh3)3Cl2] with equal equiv. of K[HB(timMe)3] at reflux afforded the neutral complex [RuH(CO)(PPh3){κ 3-S,S,H-HB(timMe)3}] (5) or [Ru(PPh3)2Cl{κ 3-S,S,H-HB(timMe)3}] (6), respectively, with an agostic BRu bond. Complex 6 was further treated with one equiv. of NatimMe in THF solution to result in formation of new complex [Ru(PPh3)(κ 2-S,N-timMe){κ 3-S,S,H-HB(timMe)3}] (7) with chelating [timMe]– moiety. All complexes were spectroscopically characterized, of which the structures of 1·1/4C6H14, 4·C6H14·3/4H2O, 5·1/2CH2Cl2, and 7·2CH2Cl2 have been established by X-ray crystallography. [ABSTRACT FROM AUTHOR]

Abstract: Chiral cyclopentadienyl ruthenium(II) complexes [CpRu(L1–L3)Cl] (5–7) have been prepared by reaction of [CpRu(PPh3)2Cl] with chiral P,P-ligands (1R,2R)-1,2-bis(diphenylphosphinamino)cyclohexane (L1), N,N′-[bis-(3,3′-bis-tert-butyl-5,5′-bis-methoxy-1,1′-biphenyl-2,2′-diyl)phosphite]-(1R,2R)-1,2-diaminocyclohexane (L2) and N,N′-[bis-(R)-1,1′-binaphtyl-2,2′-diyl)phosphite]-(1R,2R)-1,2-diaminocyclohexane (L3). The molecular structures of 5 and 6 have been determined by single-crystal X-ray analysis. Studies on catalytic activity of the cations derived from (5–7) by treatment with AgSbF6, are also reported. [ABSTRACT FROM AUTHOR]

Reactions of the tetranuclear (Cp*RuCl)4(1) with the corresponding butadienesulfinate salts Li[SO2CHCR′CHCHR] [R = R′ = H, (2a); R = H, R′ = Me, (2b); R = R′ = Me, (2c)] in THF result in the formation of tetrameric [Cp*Ru(1,2,5-η-SO2CHCR′CHCHR)LiCl]4[R = R′ = H, (3); R = H, R′ = Me, (4); R = R′ = Me, (5)] complexes. Compound 5has been isolated in two pseudo-polymorphic crystal forms as 5in space group P4̅21cand as 5·3THF, where there are three molecules of solvated THF per tetramer, in space group I4̅. Both tetramers occupied a crystallographic 4-fold-roto inversion axis. In both structures the tetramer symmetry is S4, and these distorted cubane-like kernel structures are similar to the one found in compound 1. If potassium butadienesulfinates are used in the reaction with 1instead of lithium salts 2a−c, mononuclear allylsulfene ruthenium compounds [Cp*Ru(1−5-η-SO2CHCR′CHCHR)] [R = R′ = H, (6); R = H, R′ = Me, (7)] are isolated. The analogous compound 8[R = R′ = Me] was prepared directly from addition of water to 5. Compounds 6−8are the first complexes to contain a dioxo-η5-thiapentadienyl or 1−5-η-butadienesulfonyl ligand, as confirmed by the determination of the structure of 7by X-ray crystallography. Tetrameric 3−5and monomeric 6−8easily interconvert into each other in the presence of H2O and LiCl, respectively. A comparative study of the dissociation of tetramers 1and 3, in the presence of THF, via dynamic light scattering measurements shows a tendency of 1to dissociate and favor polydisperse aggregates in THF, whereas in 3the tetranuclear structure remains essentially preserved. Furthermore, when the mononuclear 6was studied and compared to 3, only one well-defined peak was observed in each case, with the average aggregate 4:1 radius ratio. This implies that 3has aggregates 4 times larger than those formed by 6. Cyclic voltammetry confirms the formation of the ion pair [Cp*Ru(1,2,5-η-SO2CHCHCHCH2)(5-η-S(O2−K+)CHCHCHCH2)] (12a-K) from 6and 2a-Kunder stoichiometric ratio or directly from 1and excess of 2a-K. Selective exchange of the counterion occurs for 12a-Kin the presence of AgBF4and n-Bu4NBF4in THF to afford 12a-Agand 12a-(n-Bu4N). Compound 6reacts with a high excess of 2a-Li, under reflux in THF, to yield [Cp*Ru(1,2,5-η-SO2CHCHCHCH2)(5-η-S(O2−Li+)CHCHCHCH2)] (12a-Li) and [Cp*Ru(5-η-SO2CHCHCHCH2)(5-η-S(O2−Li+)CHCHCHCH2)2] (13a-Li). The equilibrium reaction between analogous 13a-Kand 12a-Kwas studied in solution by means of 1H NMR spectroscopy. HRMS provided evidence of the capacity of the SO2fragment, in the butadienesulfinate complexes, to afford new aggregation states according to the cations employed. [ABSTRACT FROM AUTHOR]

Abstract: Synthesis and characterization of the dinuclear ruthenium coordination complexes with heteroleptic ligand sets, [Cl(terpy)Ru(tpphz)Ru(terpy)Cl](PF6)2 (7) and [(phen)2Ru(tpphz)Ru(terpy)Cl](PF6)3 (8), are reported. Both structures contain a tetrapyrido[3,2-α:2′,3′-c:3′′,2′′-h:2′′,3′′-j]phenazine (tpphz) (6) ligand bridging the two metal centers. Complex 7 was obtained via ligand exchange between, RuCl2(terpy)DMSO (5) and a tpphz bridge. Complex 8 was obtained via ligand exchange between, [Ru(phen)2tpphz](PF6)2 (4) and RuCl2(terpy)DMSO (5). Metal-to-ligand-charge-transfer (MLCT) absorptions are sensitive to ligand set composition and are significantly red-shifted due to more electron donating ligands. Complexes 7–9 have been characterized by analytical, spectroscopic (IR, NMR, and UV–Vis), and mass spectrometric techniques. The electronic spectral properties of 7, 8, and [(phen)2Ru(tpphz)Ru(phen)2](PF6)4 (9), a previously reported +4 analog, are presented together. The different terminal ligands of 7, 8, and 9 shift the energy of the MLCT and the π–π* transition of the bridging ligand. These shifts in the spectra are discussed in the context of density functional theory (DFT). A model is proposed suggesting that low-lying orbitals of the bridging ligand accept electron density from the metal center which can facilitate electron transfer to nanoparticles like single walled carbon nanotubes and colloidal gold. [Copyright &y& Elsevier]

Abstract: Five trinuclear monosubstituted complexes of the type Ru3(CO)11L were synthesised by the reaction of Ru3(CO)12 with phosphine ligands (L) using the radical anion catalysed method. The structures of the resulting clusters were elucidated by means of elemental analyses and spectroscopic methods, including IR, 1H NMR, 13C NMR and 31P NMR spectroscopy. 31P NMR spectra of the complexes Ru3(CO)11P(C6H4Me-p)3 and Ru3(CO)11P(C6H4Cl-p)3 showed splitting of the phosphorus signals into triplets. X-ray crystallographic studies of all five complexes were carried out. Out of the three unidentate tertiary phosphine complexes, Ru3(CO)11P(C6H4Me-p)3 and Ru3(CO)11P(C6H4Cl-p)3 are ordered while the complex Ru3(CO)11P(3,5-CF3–C6H3)3 exhibits disorder with respect to the trifluoromethyl groups. In all the five monosubstituted complexes, the ligand occupies the equatorial position due to steric reasons and coordination of the ligands are only at the phosphorus atom. The effect of substitution resulted in significant differences in the Ru–Ru distances. Out of the three Ru–Ru bonds, the one which is cis to the ligand is noticeably longer and the mean value for this longest Ru–Ru bond is 2.889Å, while the mean value for the two shorter Ru–Ru bonds is 2.841Å. The P–C distances are in the range 2.333(6)–2.354(6)Å. The equatorial Ru–CO moieties are almost linear and the average value for all the five complexes studied range from 176.3 to 177.6°, while the axial CO groups are slightly bent, ranging from 173.8 to 174.1°. [Copyright &y& Elsevier]

Abstract: The synthesis and characterization of cationic arene ruthenium compounds [(η 6-p- i PrC6H4Me)RuCl(κ 2-dpa)]BF4 (1), [(η6 -C6H6)RuCl(κ 2-dpa)]BF4 (2), [(η 6-p- i PrC6H4Me)-RuCl(κ 2-dpb)]BF4 (3), [(η 6-p- i PrC6H4Me)RuCl(κ 2-dpb)]PF6.CH3OH (4) and [(η6 -C6H6)-RuCl(κ 2-dpb)]PF6 (5) (arene=C6H6 or p- i PrC6H4Me; dpa=2,2′-dipyridylamine and dpb=di-2-pyridylbenzylamine) have been described. Reactions of the representative compounds 1 and 3 with NaN3, NaCN, and NH4SCN afforded substitution products [(η 6-p- i PrC6H4Me)-Ru(κ 2-dpa)(N3)]BF4 (6), [(η 6-p- i PrC6H4Me)Ru(κ 2-dpa)(CN)]BF4 (7), [(η 6-p- i PrC6H4Me)-Ru(κ 2-dpa)(NCS)]BF4 (8), [(η 6-p- i PrC6H4Me)Ru(κ 2-dpb)(N3)]BF4 (9), [(η 6-p- i PrC6H4Me)-Ru(κ 2-dpb)(CN)]BF4 (10) and [(η 6-p- i PrC6H4Me)Ru(κ 2-dpb)(NCS)]BF4 (11). The compounds under investigation have been characterized by elemental analyses, spectroscopic and electrochemical studies. Molecular structures of 1, 3, 4 and 5 have been determined crystallographically. The compounds 1–3 and 5 exhibited moderate catalytic activity in the reduction of ketones into corresponding alcohol in absence of a base. [Copyright &y& Elsevier]

The reaction of α,β-unsaturated imines with [(1,5-cyclooctadiene)-bis(2-methylallyl)-ruthenium(II)] leads to the formation of mononuclear ruthenium complexes of the general formula {(COD)Ru[RN＝C(H)–C(H)＝C(Ph)]2}. In these complexes the imine ligands are deprotonated in β-position with respect to the imine double bond and coordinate as an enyl-imino ligand. In the case of R=Me, Et the corresponding compounds have been characterized by X-ray crystallography. The relevance of these complexes with respect to ruthenium catalyzed C–C coupling reactions of the same α,β-unsaturated imines is demonstrated by the structural analysis of another mononuclear ruthenium complex in which two imine ligands are reductively coupled (R=Cy). [(1,5-Cyclooctadiene)-bis(2-methylallyl)-ruthenium(II)] also turns out to be a highly effective precatalyst in the reaction of the respective imines with carbon monoxide and ethylene to produce heterocyclic compounds. [ABSTRACT FROM AUTHOR]

Abstract: Three simple ruthenium nitrosyl complexes of the compositions [Et 4N][RuCl4(NO)(DMSO)] (1), [Bu 4N][RuCl4(NO)(DMSO)] (2), and [Ph 4P][RuCl4(NO)(H2O)]·DMSO (3); where DMSO=dimethyl sulfoxide, Et= ethyl, Bu= butyl and Ph= phenyl, have been synthesized in the single crystal form and their molecular and crystal structures have been determined. The Ru(II) centre is six-coordinated by four chlorido ligands in the equatorial plane and by the N (from NO+) and O (from DMSO in 1 and 2, H2O in 3) atoms in the axial positions forming an RuCl4NO donor set. The complexes have been also characterized by infrared and electronic spectroscopies, conductivity measurements, and thermogravimetric (TG) and differential thermal (DTA) analyses. The spectroscopic investigation is consistent with the {Ru(NO)}6 formulation with NO+ coordinated to the diamagnetic Ru(II) centre. The geometries of the complex anions as well as spectroscopic properties were calculated at the B3LYP/LANL2DZ/cc-pVTZ level of theory. These results were compared with those experimentally determined. [Copyright &y& Elsevier]

Abstract: A solid-state electrochemiluminescence (ECL) biosensing switch incorporating quenching of ECL of ruthenium(II) tris-(bipyridine) (Ru(bpy)3 2+) by ferrocene (Fc) has been successfully developed for DNA hybridization detection. The important issue for this biosensing system is based on the ferrocene-labeled molecular beacon (Fc-MB), i.e. using the special Fc-MB to react with the target DNA and then change its structure, resulting in an ECL intensity change. Under the optimal conditions, the difference of ECL intensity before and after the hybridization reaction (ΔI ECL) was linearly related to the concentration of the complementary sequence in the range of 10fM–10pM and the detection limit was down to 1.0fM. [Copyright &y& Elsevier]

Abstract: Ruthenium(II)octa-(n-hexyl)-phthalocyanine [(n-hexyl)8PcRu] (2) thin films have been deposited on different substrates by thermal evaporation technique under high vacuum. X-ray diffraction (XRD) pattern of [(n-hexyl)8PcRu] (2) in the powder form indicated that it has polycrystalline form with a triclinic structure. The XRD results for [(n-hexyl)8PcRu] (2) thin films confirm the amorphous nature for the as-deposited films. The optical properties of [(n-hexyl)8PcRu] (2) were investigated for as-deposited and irradiated films using spectrophotometric measurements of the transmittance and reflectance at normal incidence of light in the wavelength range from 200 to 2500nm. The recorded absorption measurements in the UV–vis region show two well defined absorption bands of phthalocyanine molecule; namely the Q-band and the Soret (B-band). The refractive index (n) and the absorption index (k) were calculated. According to the analysis of dispersion curves, the parameters, namely; the optical absorption coefficient (α), molar extinction coefficient (ɛ molar), oscillator energy (E o), oscillator strength (f), and electric dipole strength (q 2) were also evaluated. The analysis of the spectral behaviour of the absorption coefficient (α), in the absorption region revealed indirect transitions. [Copyright &y& Elsevier]

Abstract: The “Ru(P–P)” unit (P–P=diphosphine) is recognized to be an important core in catalytic species for hydrogenation of unsaturated organic substrates. Thus, in this study we synthesized six new complexes containing this core, including the binuclear complex [(dppb)(CO)Cl2Ru-pz-RuCl2(CO)(dppb)] (pz=pyrazine) which can be used as a precursor for the synthesis of cationic carbonyl species of general formula [RuCl(CO)(dppb)(N–N)]PF6 (N–N=diimine). Complexes with the formula [RuCl(py)(dppb)(N–N)]PF6 were synthesized by exhaustive electrolysis of these carbonyl compounds or from the precursors [RuCl2(dppb)(N–N)]. The new complexes were characterized by microanalysis, conductivity measurements, IR and 31P{1H} NMR spectroscopy, cyclic voltammetry and X-ray crystallography. [Copyright &y& Elsevier]

Abstract: This review provides an overview of density functional theory (DFT) calculations in a consequence with spectroelectrochemical measurements on mononuclear and symmetrically or unsymmetrically bridged di- and tetranuclear ruthenium complexes of vinyl and TCNX ligands. The DFT approach is used for the calculations of molecular structures, vibrational frequencies, electronic and electron paramagnetic resonance (EPR) spectral data. DFT calculations enable us to identity the primary redox site and the electron and spin-density distribution between the individual components for the individual redox congeners. The DFT technique reproduces the spectral properties of the presented complexes and their radical ions. The generally close correspondence between experimental and quantum chemical results demonstrate that modern DFT is a powerful tool to address issues like ligand non-innocence and electron and spin delocalization in systems containing both redox-active metal ions and redox-active ligands. [Copyright &y& Elsevier]

Abstract: Reaction of the cis-[RuCl2(dmso)4] with pyridine (py) at room temperature in MeOH/H2O afforded a neutral mononuclear complex cis,cis,cis-[RuCl2(py)2(dmso-S)2] 1. The complex 1 reacted with nitrogen donor bases such as pyridine (py), pyrazine (pyz), 4,4′-bipyridine (bp) and 1,4-bis(4-pyridyl)ethane (bpeta) in different solvents to give substitution products. The nature of the substitution product was governed by the polarity of the solvents employed in the reaction. Resulting complexes have been characterized by elemental analyses, IR, NMR (1H and 1H–1H COSY), ESI-MS, FAB-MS and electronic spectral studies. Molecular structures of the complexes 1 and 5 have been determined crystallographically. Complex 1 exhibits the strong intra- and inter-molecular CX (X=Cl, π) and face-to-face π–π stacking interactions but only intra- and inter-molecular CCl and π–π stacking interactions are present in 5 which play important roles to stabilize crystal packing. Furthermore, the CO interactions in 1 and CCl interactions in 5 lead to a single and double-helical motif. [Copyright &y& Elsevier]

Abstract: Ruthenium complexes [Ru(mpy)2(DMSO)2] (1) and [Ru(mbtz)2(DMSO)2] (2) containing 2-mercaptopyridine (mpy) and 2-mercaptobenzothiazole (mbtz) have been synthesized. Reactivity of 1 have been examined with 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), EPh3 (E=P, As) and 1,2-bis(diphenylphosphino)-methane (dppm). It reacted with bipy or phen in DMF to afford [Ru(mpy)2(bipy)] (3) and [Ru(mpy)2(phen)] (4) while, its reaction with EPh3 or dppm in common organic solvents failed to afford products containing EPh3 or dppm. Complexes under investigation have been characterized by elemental analyses, spectral, electrochemical studies and structures of 1–4 have been determined crystallographically. Density functional theory calculations have been performed on 1–4 and the model complex [Ru(mpy)(PMe3)2] (5) using exchange correlation functionals BP86. Optimized bond length and angles are in good agreement with the structural data. The Ru–N and Ru–S bond distances in [Ru(mpy)2]-moiety of 1 are relatively shorter than 5, indicating higher stability of 1 in comparison to 5. The WBI values of Ru–N1, Ru–N2, Ru–S1 and Ru–S2 bonds indicate Ru–mpy bonding trend as 3 > 4 > 1 > 5. There is an overall charge flow in the direction L→[Ru(mpy)2] (L=DMSO, bipy, phen and PMe3). Due to greater ionic character and Pauli repulsive interactions for Ru–PMe3 bond in comparison to Ru–DMSO, the DMSO ligands in 1 may not be substituted by phosphine ligands experimentally. [Copyright &y& Elsevier]

Abstract: Structural analysis of a previously reported half-sandwich complex having three-legged “piano-stool” geometry [(η6-C6H6)RuII(L1)Cl][PF6] (1) (L1 = 2-(pyrazol-1-ylmethyl)pyridine) is described. Treatment of 1 with (i) Ag(CF3SO3) in CH3CN and (ii) NaN3 in CH3OH, and (iii) the reaction between [(η6-C6H6)Ru(L2)Cl]-[PF6] (2) (previously reported) and NaCN in C2H5OH led to the isolation of [(η6-C6H6)Ru(L1)(CH3CN)][PF6]2 (3), [(η6-C6H6)Ru(L1)(N3)][PF6] (4), and [(η6-C6H6)Ru(L2)(CN)][PF6] (5), respectively (L2 = 2-(3,5-dimethyl-pyrazol-1-ylmethyl)pyridine). The complex [(η6-C6H6)Ru(L4)Cl][PF6] (6) with a new ligand (L4 = 2-[3-(4-fluorophenyl)pyrazol-1-ylmethyl]pyridine) has also been synthesized. The structures of 3–6 have been elucidated (1H NMR spectra; CD3CN). The molecular structures of 1, 4, and 6·C6H5CH3 have been determined. Notably, the crystal-packing in these structures is governed by C–H⋯X (X = Cl, N) interactions, generating helical architectures. [Copyright &y& Elsevier]

The reaction of Ru3(CO)12in chloroform with thioether ligands after 25 min of irradiation leads to the formation of mononuclear ruthenium(ii) complexes of the general formula fac-[Ru(CO)3Cl2(S)] (S = thioether) if monodentate ligands are introduced. In the case of chelating bidentate thioethers a complex of the formula all-cis-[Ru(CO)2Cl2(S∩S)] is produced. If irradiation time is prolonged to 2.5 h mononuclear complexes of the composition trans-[RuCl2(S)4] or trans-[RuCl2(S∩S)2] are observed. The use of tetrahydrothiophene (THT) in the latter case produces a dinuclear ruthenium(ii) complex of the formula [Ru2(CO)2Cl4(THT)2(μ-THT)2] which is the first structurally characterized neutral ruthenium complex with a bridging thioether ligand. Regardless of the used ligand complexes trans-[RuCl2(S)4] or trans-[RuCl2(S∩S)2] are formed from the reaction of RuCl3·3H2O with the corresponding thioether in the presence of NEt3and formaldehyde in excellent yields. Six new ruthenium complexes are characterized by X-ray diffraction. [ABSTRACT FROM AUTHOR]