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Complexes Containing (complex + containing)
Selected AbstractsSynthesis and Characterization of a Gold Complex Containing [SbPh]2, and [SbPh2], Anions as Bridging LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2007Dieter Fenske Abstract The synthesis and structural characterization of the gold antimony complex [Au8(SbPh)2(SbPh2)4(PEt3)6] (1) is reported. Complex 1 can be obtained by the reaction of [AuCl(PEt3)] with a mixture of PhSb(SiMe3)2 and Ph2(SbSiMe3) in presence of the bidentate phosphane ligand dppm [dppm = bis(diphenylphosphanyl)methane]. Complex 1 consists of a distorted heterocubic central [Au6Sb2] unit connected to two annulated five-membered rings on two opposite edges. The AuI ions show weak aurophilic interactions and are bridged by [SbPh]2, and [SbPh2], anions. Despite the high oxidation potential of AuI, the reaction mixtures and crystals are surprisingly stable. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Cytotoxic Rhodium(III) Polypyridyl Complexes Containing the Tris(pyrazolyl)methane Coligand: Synthesis, DNA Binding Properties and Structure,Activity RelationshipsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2009Ruth Bieda Abstract The RhIII complexes of the type [RhCl(pp)(tpm)]2+ [pp = bpy, bpm, phen, tap, dpq, dppz] 4,9 have been prepared by stepwise treatment of RhCl3·3H2O or mer,cis -[RhCl3(DMSO-,S)2(DMSO-,O)] with the appropriate polypyridyl ligand (pp) followed by the tripodal ligand tris(pyrazolyl)methane (tpm). Intermediates of the type [RhCl3(CH3OH)(pp)] 1,3 with pp = bpy, phen, dpq were also characterized but exhibit either low (3) or no (1, 2) cytotoxicity. X-ray structural analyses of [RhCl(bpy)(tpm)][PF6]24 and [RhCl(phen)(tpm)][PF6]26 were performed, and the interaction of complexes 4,9 with DNA was investigated by CD and UV/Vis spectroscopy and by gel electrophoresis. CD and viscosity studies confirm strong intercalation of dppz complex 9 into DNA. Complexes 8 and particularly 9 (IC50 = 0.43, 0.37 ,M) are potent cytotoxic agents towards the human cancer cell lines MCF-7 and HT-29, whereas respectively little (complex 6) or no activity (complexes 4, 5, 7) is observed for the other members of the series. Our findings indicate that the cytotoxicity is dependent on the hydrophobicity of both the polypyridyl and the facial coligand in these and other half-sandwich RhIII complexes. Irradiation of bpy compound 4 in the presence of plasmid pBR322 for 30 min at 311 nm at a molar ratio of r = 0.1 leads to total conversion of the supercoiled form into the nicked version. Although dppz complex 9 also functions as a photonuclease under these conditions, the degree of cleavage is much lower. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Structures, Redox and Spectroscopic Properties of PdII and PtII Complexes Containing an Azo FunctionalityEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2009Sayak Roy No abstract is available for this article. [source] Mechanistic Insights into Acetophenone Transfer Hydrogenation Catalyzed by Half-Sandwich Ruthenium(II) Complexes Containing 2-(Diphenylphosphanyl)aniline , A Combined Experimental and Theoretical StudyEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 28 2008Alessia Bacchi Abstract Several new half-sandwich ruthenium(II) complexes containing 2-(diphenyphosphanyl)aniline (PNH2) of formula {Ru[(,2P,N)PNH2](p -cymene)Cl}Y [Y = Cl (1a), PF6 (1b), BF4 (1c), BPh4 (1d), TfO (1e)] were synthesized and fully characterized both in solution (1H NMR and 31P{1H} NMR spectroscopy) and in the solid state (FTIR, X-ray analysis on single crystal). Complexes 1a and 1b are active precatalysts in the hydrogen transfer reaction of acetophenone, leading to tof values up to 4440 h,1. In comparison, the {Ru[(,2P,N)PNMe2](p -cymene)Cl}Cl complex leads to a tof value of 100 h,1 under the same catalytic conditions. The mechanism through which the precatalysts operate was deeply explored by high-resolution MS (ESI) and DFT/PCM studies. The results reveal that the complexes containing PNH2 operate through a bifunctional mechanism analogous to that proposed for diamines and amino alcohol ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Luminescent Gold(I) and Copper(I) Phosphane Complexes Containing the 4-Nitrophenylthiolate Ligand: Observation of ,,,* Charge-Transfer EmissionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2008Cheng-Hui Li Abstract Gold(I) and copper(I) phosphane complexes containing the 4-nitrophenylthiolate ligand, namely [(PCy3)Au(SC6H4NO2 -4)] (1) (PCy3 = tricyclohexylphosphane), [Au2(,-dcpm)(SC6H4NO2 -4)2] (2) [dcpm = bis(dicyclohexylphosphanyl)methane], [Au2(,-dppm)(SC6H4NO2 -4)2] (3) [dppm = bis(diphenylphosphanyl)methane], and [(,2 -SC6H4NO2 -4)2(,3 -SC6H4NO2 -4)2(CuPPh3)4] (4), were prepared and characterized by X-ray crystal analysis. All of these complexes show an intense absorption band with ,max at 396,409 nm attributed to the intraligand (IL) ,(S),,*(C6H4NO2 -4) charge-transfer transition. The assignment is supported by the results of DFT and TDDFT calculations on the model complexes [PH3Au(SC6H4NO2 -4)] and [(,2 -SC6H4NO2 -4)2(,3 -SC6H4NO2 -4)2(CuPH3)4]. The emissions of solid samples and glassy solutions (methanol/ethanol, 1:4, v/v) of 1,4 at 77 K are assigned to the [,(S),,*(C6H4NO2 -4)] charge-transfer excited state. Metallophilic interactions are not observed in both solid state and solutions of complexes 1,3. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis and Reactions of Polynuclear Polyhydrido Rare Earth Metal Complexes Containing "(C5Me4SiMe3)LnH2" Units: A New Frontier in Rare Earth Metal Hydride ChemistryEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2007Zhaomin Hou Abstract A series of tetranuclear octahydrido rare earth metal complexes of general formula [(C5Me4SiMe3)Ln(,-H)2]4(THF)n (Ln = Sc, Y, Gd, Dy, Ho, Er, Tm, Lu; n = 0, 1, or 2) that contain C5Me4SiMe3 as an ancillary ligand have been prepared and structurally characterized. These hydride clusters are soluble in common organic solvents such as THF, toluene, and hexane, and maintain their tetranuclear framework in solution. Such polynuclear polyhydrido complexes exhibit extremely high and unique reactivity toward a variety of unsaturated substrates including CO, CO2, and nitriles. The reaction of these neutral polyhydrides with one equivalent of [Ph3C][B(C6F5)4] affords the corresponding cationic hydride clusters [(C5Me4SiMe3)4Ln4H7(THF)n][B(C6F5)4], which can act as catalysts for the syndiospecific polymerization of styrene and regio- and stereospecific cis -1,4-polymerization of 1,3-cyclohexadiene. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A Magnetostructural and Electrochemical Study of CuII and FeIII Complexes Containing a Tetradentate Aminebis(phenolate) Ligand with a Pendent Tetrahydrofuran GroupEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2007Elham Safaei Abstract Ligating properties of a tetradentate ligand 2-{bis[(3,5-di- tert -butyl-2-hydroxybenzyl)amino]methyl}tetrahydrofuran,H2L, with [O,O,N,O]-donor atoms towards CuII and FeIII are described. The ligand H2L yields both mononuclear LFeIII(acac) (1) and dinuclear [L2FeIII2(,-OCH3)-(,-OH)] (2), [L2FeIII2(,-C2O4)] (3) and [L2CuII2] (4) complexes, which were characterized by various physical techniques, including X-ray diffraction, Mössbauer, electrochemical and magnetic susceptibility (2,290 K) measurements. That the electrochemical oxidations are ligand-centered, i.e. formation of phenoxyl radicals from the coordinated phenolates, have been shown by voltammetric methods. Complexes 2,4 display antiferromagnetic exchange coupling of the neighbouring metal centers. Comparison of the evaluated weak exchange coupling constants (J) with the literature values leads to the conclusion that the angle Cu,O,Cu, is not the only determinant for the nature of the exchange coupling and the capability of the bridging ligands as mediators for spin coupling in case of FeIII follows the order phenoxide , methoxide > hydroxide. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Binuclear Mixed Valence Oxovanadium(IV/V) Complexes Containing a [OVIV(,-Ooxo)(,-Ophen)VVO]2+ Core: Synthesis, EPR Spectra, Molecular and Electronic StructureEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2006Amrita Mondal Abstract Binuclear mixed valence oxovanadium(IV/v) complexes of general formula [V2O3L] containing a [OVIV(,-Ooxo)(,-Ophen)VVO]2+ core have been synthesised using conformationally labile N4O3 -coordinating heptadentate ligands (H3L). The X-ray structure of one complex has been examined. Solution EPR spectra revealed that the unpaired electron of the complexes is delocalised between the two vanadium centres. The simulated EPR spectrum of one complex confirms this experimental observation. DFT studies have been performed using crystallographic coordinates in order to obtain further insight into the electronic structure of this type of molecule. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Water-Soluble Arene Ruthenium Complexes Containing a trans -1,2-Diaminocyclohexane Ligand as Enantioselective Transfer Hydrogenation Catalysts in Aqueous SolutionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2005Jérôme Canivet Abstract The cationic chloro complexes [(arene)Ru(H2N,NH2)Cl]+ (1: arene = C6H6; 2: arene = p -MeC6H4iPr; 3: arene = C6Me6) have been synthesised from the corresponding arene ruthenium dichloride dimers and enantiopure (R,R or S,S) trans -1,2-diaminocyclohexane (H2N,NH2) and isolated as the chloride salts. The compounds are all water-soluble and, in the case of the hexamethylbenzene derivative 3, the aqua complex formed upon hydrolysis [(C6Me6)Ru(H2N,NH2)OH2]2+ (4) could be isolated as the tetrafluoroborate salt. The molecular structures of 3 and 4 have been determined by single-crystal X-ray diffraction analyses of [(C6Me6)Ru(H2N,NH2)Cl]Cl and [(C6Me6)Ru(H2N,NH2)OH2][BF4]2. Treatment of [Ru2(arene)2Cl4] with the monotosylated trans -1,2-diaminocyclohexane derivative (TsHN,NH2) does not yield the expected cationic complexes, analogous to 1,3 but the neutral deprotonated complexes [(arene)Ru(TsN,NH2)Cl] (5: arene = C6H6; 6: arene = p -MeC6H4iPr; 7: arene = C6Me6; 8: arene = C6H5COOMe). Hydrolysis of the chloro complex 7 in aqueous solution gave, upon precipitation of silver chloride, the corresponding monocationic aqua complex [(C6Me6)Ru(TsHN,NH2)(OH2)]+ (9) which was isolated and characterised as its tetrafluoroborate salt. The enantiopure complexes 1,9 have been employed as catalysts for the transfer hydrogenation of acetophenone in aqueous solution using sodium formate and water as a hydrogen source. The best results were obtained (60 °C) with 7, giving a catalytic turnover frequency of 43 h,1 and an enantiomeric excess of 93,%. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthesis and Structural Characterization of Three-Coordinate MnII, FeII, and ZnII Complexes Containing a Bulky Diamide Ligand [DippN(CH2)3NDipp]2, (Dipp = 2,6- iPr2C6H3)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2004Jianfang Chai Abstract The reaction of DippNH(CH2)3NHDipp (1) (Dipp = 2,6- iPr2C6H3) with 2 equiv. of MeLi in diethyl ether resulted in the formation of the monomeric dilithium salt [(Dipp)N(CH2)3N(Dipp)][Li(OEt2)]2 (2) in high yield. Further reactions of 2 with MnCl2, FeCl2, and ZnCl2, respectively, afforded the complexes [M2{N(Dipp)(CH2)3N(Dipp)}2] [M = Mn (3), Fe (4), Zn (5)] with three-coordinate metal centers. Complexes 2,5 were characterized by X-ray structural analysis. The complexes contain a nonplanar MNMN central core. The diamide ligand in complexes 3,5 displays a boat conformation and is both chelating and bridging, so that one of the nitrogen atoms is three-coordinate and the other four-coordinate. Complexes 3,5 are the first examples with diamide ligands in such a bonding mode. The magnetic investigations of compounds 3 and 4 reveal an antiferromagnetic exchange between the metal atoms. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis of (Vinylidene)- and (Cyclopropenyl)ruthenium Complexes Containing a Tris(pyrazolyl)borato (Tp) LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2004Yih-Hsing Lo Abstract A convenient high-yield route to [Ru(C,C,Ph)(Tp)(PPh3)2] [2; Tp = HB(pz)3, pz = pyrazolyl] has been found through the intermediacy of [RuCl2(Hpz)2(PPh3)2] (1). This complex is readily obtained on treatment of [RuCl2(PPh3)3] with 2 equiv. of pyrazole in boiling THF. The molecular structures of complexes 1 and 2 have been confirmed by single-crystal X-ray diffraction analysis. A number of new cationic vinylidene complexes [Ru{=C=C(Ph)CH2R}(Tp)(PPh3)2]+ [3a, R = CN; 3b, R = HC=CH2; 3c, R = CH=C(CH3)2; 3d, R = Ph; 3e, R = C(O)OMe] have been prepared by electrophilic addition of organic halides to complex 2. The deprotonation reaction of 3a yields the cyclopropenyl complex 4a. One phosphane ligand of 4a is remarkably labile, being replaced by donor ligands L to yield diastereomeric mixtures of the cyclopropenyl complexes 5a,5d mostly in an approximate 4:1 ratio. The cyclopropenyl rings in 4a and 5a are susceptible to ring opening by I2. In addition, treatment of 4a with nBuNC in the presence of MeOH results in substitution of a phosphane ligand by nBuNC followed by protonation of the three-membered ring by MeOH. This is then followed by addition of methoxide to give the vinyl ether complex [Ru{C(OMe)=C(Ph)CH2CN}(Tp)(PPh3)(nBuNC)] (8a). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Dimeric 2,2,-Bipyridylruthenium(II) Complexes Containing 2,2,-Bis(1,2,4-triazin-3-yl)-4,4,-bipyridine-Like Bridging Ligands: Syntheses, Characterization and DNA BindingEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2004Cai-Wu Jiang Abstract Three new bridging ligands 2,2,-bis(1,2,4-triazin-3-yl)-4,4,-bipyridine (btb), 2,2,-bis(1,2,4-triazino[5,6-f]acenaphthylen-3-yl)-4,4,-bipyridine (btapb), 2,2,-bis(5,6-diphenyl-1,2,4-triazin-3-yl)-4,4,-bipyridine (bdptb) and their dimeric 2,2,-bipyridylruthenium(II) complexes [Ru(bpy)2(btb)Ru(bpy)2]4+ (1), [Ru(bpy)2(btapb)Ru(bpy)2]4+ (2), [Ru(bpy)2(bdptb)Ru(bpy)2]4+ (3) have been synthesized and characterized by elemental analysis, fast atom bombardment (FAB) mass spectrometry or electrospray mass spectrometry (ES-MS), 1H NMR and UV/Visible spectroscopy. The binding behavior of these dimeric complexes with calf thymus DNA (CT-DNA) was investigated by electronic absorption spectroscopy, viscosity measurements, and equilibrium dialysis experiments. The hypochromism of the metal-ligand charge transfer (MLCT) band in the electronic absorption spectra of the dinuclear complexes 1, 2, and 3 is 8.7%, 19% and 33%, respectively, with bathochromic shifts of 5, 5 and 14 nm, respectively. The binding constants are 7.5×104M,1, 4.8×105M,1 and 7.6×105M,1, respectively. Increasing the size of the plane of the bridging ligand increases the hydrophobicity of their complexes, leading to stronger binding by the complexes to calf thymus DNA. The effect of increasing concentrations of these novel dimeric ruthenium(II) complexes on the relative viscosities of CT-DNA is less notable than that of well-known intercalators such as [Ru(bpy)2(dppz)]2+. The equilibrium experiments showed that ,,,3 binding is stronger than ,,,3 binding to CT-DNA. This is the first example of a dinuclear complex binding enantioselectively to CT-DNA measured by equilibrium dialysis. The experiments suggest that the three complexes may be DNA groove binders. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Coenzyme B12 Model Studies , Kinetics of Axial Ligation of Alkylcobalt Complexes Containing a Tridentate Amino-Oximate LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2003Basam M. Alzoubi Abstract The ligand-substitution reaction of [RCo(LNHpy)(HLNHpy)]+ by cyanide was studied in methanol as a solvent, where R = Et (1), Me (2), CF3CH2 (3), and bridging CH2 (4), HLNHpy = 2-(2-pyridylethyl)amino-3-butanone oxime and LNHpy, is its conjugate base. The second-order rate constants for the substitution of the 2-pyridylethyl moiety in [RCo(LNHpy)(HLNHpy)]+ by cyanide were found to be 19.1, 0.25, 2.2·10,2, and 1.7·10,2M,1·s,1 for R = Et, Me, CF3CH2, and bridging CH2, respectively. From the temperature- and pressure-dependence studies of the substitution reaction, the activation parameters (,H,, ,S,, ,V,) for the reaction of [RCo(LNHpy)(HLNHpy)]+ with cyanide in methanol were found to be, for R = Et: 69±2 kJ·mol,1, +11±7 J·K,1 mol,1, +9.6±0.3 cm3·mol,1; R = Me: 86±4 kJ·mol,1, +31±15 J·K,1·mol,1, +4.3±0.2 cm3·mol,1; R = CF3CH2: 73±3 kJ·mol,1, ,33±10 J·K,1·mol,1, +8.7±0.2 cm3·mol,1; R = bridging CH2: 80±1 kJ·mol,1, ,13±3 J·K,1·mol,1, +5.4±0.1 cm3·mol,1, respectively. Based on the reported rate and activation parameters, the mechanism of the ligand-substitution reaction varies between a limiting dissociative and a dissociative interchange type of mechanism depending on the ,-donor and steric effects of the alkyl group. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Novel Chiral (Salen)MnIII Complexes Containing a Calix[4]arene Unit as Catalysts for Enantioselective Epoxidation Reactions of (Z)-Aryl AlkenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2005Maria E. Amato Abstract New asymmetric (salen)MnIII and UO2 complexes containing a calix[4]arene unit in the ligand framework were synthesized. The UO2 complexes were characterized by 1H-, 13C-, 2D TOCSY and T-ROESY NMR spectroscopy. Furthermore, the structure of one UO2 complex was determined by single-crystal X-ray analysis. The data showed that UO2 complexes, which can be considered in first approximation models of the Mn=O oxidant active species, possess a chiral pocket and adopt relevant conformations for the selectivity of the oxygen transfer process. Epoxidation data of model alkenes with the MnIII complexes showed moderate ee values and were not conclusive in indicating that the calix[4]arene unit might be able to influence the selectivity by a molecular recognition mechanism. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Effects of Zinc(II) on the Luminescence of Europium(III) in Complexes Containing , -Diketone and Schiff BasesHELVETICA CHIMICA ACTA, Issue 11 2009Yuko Hasegawa Abstract The UV, excitation, and luminescence spectra of tris(pivaloyltrifluoroacetonato)europium(III) ([Eu(pta)3]; Hpta=1,1,1-trifluoro-5,5-dimethylhexane-2,4-dione=HA) were measured in the presence of bis(salicylidene)trimethylenediamine (H2saltn), bis[5-(tert- butyl)salicylidene]trimethylenediamine (H2(tBu)saltn), or bis(salicylidene)cyclohexane-1,2-diyldiamine (H2salchn), and the corresponding ZnII complexes [ZnB] (B=Schiff base). The excitation and luminescence spectra of the solution containing [Eu(pta)3] and [Zn(salchn)] exhibited much stronger intensities than those of solutions containing the other [ZnB] complexes. The introduction of a tBu group into the Schiff base was not effective in sensitizing the luminescence of [Eu(pta)3]. The luminescence spectrum of [ZnB] showed a band around 450,nm. The intensity decreased in the presence of [Eu(pta)3], reflecting complexation between [Eu(pta)3] and [ZnB]. On the basis of the change in intensity against the concentration of [ZnB], stability constants were determined for [Eu(pta)3Zn(saltn)], [Eu(pta)3Zn{(tBu)saltn}], and [Eu(pta)3Zn(salchn)] as 4.13, 4.9 and 5.56, respectively (log,, where =[[Eu(pta)3ZnB]]([[Eu(pta)3]][[ZnB]]),1). The quantum yields of these binuclear complexes were determined as 0.15, 0.11, and 0.035, although [Eu(pta)3Zn(salchn)] revealed the strongest luminescence at 613,nm. The results of X-ray diffraction analysis for [Eu(pta)3Zn(saltn)] showed that ZnII had a coordination number of five and was bridged with EuIII by three donor O-atoms, i.e., two from the salicylidene moieties and one from the ketonato group pta. [source] Synthesis and Characterization of Copper Complexes Containing the Tripodal N7 Ligand Tris{2-[(pyridin-2-ylmethyl)amino]ethyl}amine (=N,-(Pyridin-2-ylmethyl)- N,N -bis{2-[(pyridin-2-ylmethyl)amino]ethyl}ethane-1,2-diamine): Equilibrium, Spectroscopic Data, and Crystal Structures of Mono- and Trinuclear Copper(II) ComplexesHELVETICA CHIMICA ACTA, Issue 9 2005Christian Gérard The stability constants of the CuII chelates with the tripodal heptadentate ligand tris{2-[(2-pyridylmethyl)amino]ethyl}amine (=N,-(pyridin-2-ylmethyl)- N,N -bis{2-[(pyridin-2-ylmethyl)amino]ethyl}ethane-1,2-diamine; tpaa), determined by potentiometry and UV spectrometry, show the formation of [Cu(tpaaH)]3+ and [Cu(tpaa)]2+ species. In the solid state, two mononuclear CuII compounds, [Cu(tpaa)](PF6)2 (1) and [Cu(tpaaH)](ClO4)3,H2O (2), and one trinuclear [Cu3(tpaa)2(ClO4)2](ClO4)4,2,H2O (3) complex were isolated and characterized by IR, UV/VIS, and EPR spectroscopy. An X-ray structure of the mononuclear protonated complex 2 shows that the Cu2+ ion has a distorted square-pyramidal geometry (,=0.21). and the proton is bound to the secondary-amine function of one uncoordinated arm of the tripod ligand (Fig.,4). The crystal lattice for 2 is stabilized by the H-bonds between the N-atom of the free pyridinyl group with the proton of the free secondary-amine function of the neighboring molecule. The linear trinuclear complex 3 consists of two entities of the pyramidal mononuclear complex 1 bound to the third central Cu2+ ion by the free unprotonated arms of the ligands in equatorial position (Fig.,5). The octahedral geometry of the third CuII atom is achieved by two perchlorate anions in the axial positions. The redox properties of 1,3 compounds was examined by cyclic voltammetry. [source] Water-Soluble Group 8 and 9 Transition Metal Complexes Containing a Trihydrazinophosphaadamantane Ligand: Catalytic Applications in Isomerization of Allylic Alcohols and Cycloisomerization of (Z)-Enynols in Aqueous MediumADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12-13 2006Abstract An optimized synthesis of the 2,4,10-trimethyl-1,2,4,5,7,10-hexaaza-3-phosphatricyclo[3.3.1.13,7]decane ligand (THPA) is described. It readily reacts with the dimers [{RuCl(,-Cl)(,6 -arene)}2] and [{MCl(,-Cl)(cod)}2] to yield the corresponding mononuclear complexes [RuCl2(THPA)(,6 -arene)] [arene=C6H6 (4a), p -cymene (4b), 1,3,5-C6H3Me3 (4c), C6Me6 (4d)] and [MCl(THPA)(cod)] [M=Rh (7a), Ir (7b)], respectively. Treatment of 4a and b with MeOTf affords the cationic derivatives [RuCl2(THPA-Me)(,6 -arene)][OTf] {arene=C6H6 (5a), p -cymene (5b); THPA-Me=1,2,4,10-tetramethyl-2,4,5,7,10-pentaaza-1-azonia-3-phosphatricyclo[3.3.1.13,7]decane}. The arene-ruthenium(II) complexes 4a,d and 5a and b are efficient catalysts for the redox isomerization of allylic alcohols into carbonyl compounds in both THF and aqueous media. The catalytic systems can be recycled by a simple extraction process and used in up to 4 consecutive runs. All the water-soluble complexes prepared in this work are able to promote the cycloisomerization of (Z)-enynols to afford furans in water, the best performance being obtained with the iridium catalyst 7b. Furthermore, 7b has shown an excellent recyclability (10 runs). This study represents the first example of iridium-catalyzed cycloisomerization of (Z)-enynols. [source] Preparation, Properties, and Catalytic Activity of Transition-Metal Complexes Containing a Ligated 2-Methyl,3,3-diphenyl-1,3-diphosphapropene Skeleton.CHEMINFORM, Issue 6 2004Hongze Liang Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis and Properties of DNA Complexes Containing 2,2,6,6-Tetramethyl-1-piperidinoxy (TEMPO) Moieties as Organic Radical Battery MaterialsCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2008Jinqing Qu Dr. Abstract We report here the first example of organic radical battery with DNA. Though there is a growing interest in DNA/cationic-lipid complexes as promising gene delivery vehicles, few efforts have been focused on the use of such complexes as advanced materials for organic optoelectronic applications. The present article describes how substitution of the sodium counter cation of DNA with cationic amphiphilic lipid(1,4) provided novel DNA,lipid complexes that contain TEMPO radicals, in which the actual mole ratio of phosphate to lipid was 1:0.84 to 1:0.16. All the TEMPO-containing DNA,lipid complexes displayed reversible two-stage charge/discharge processes, the discharge capacities of which were 40.5,60.0,A,h,kg,1. In particular, the capacity of a DNA,lipid(3)-based cell reached 60.0,A,h,kg,1, which corresponds to 192,% relative to its theoretical value for the single-electron one-stage process, indicating a two-electron process. [source] Ytterbocenes as One- and Two-Electron Reductants in their Reactions with Diazadienes: YbIII Mixed-Ligand Bent-Sandwich Complexes Containing a Dianion of DiazabutadieneCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2007Alexander Abstract Ytterbocene [Yb(C5MeH4)2(thf)2] reacts with diazabutadiene 2,6- iPr2C6H3NCHCHNC6H3iPr2 -2,6 (DAD) as a one-electron reductant to afford a bis(cyclopentadienyl) YbIII derivative containing a DAD radical anion [Yb(C5MeH4)2(dad,.)]. However, ytterbocenes [YbCp*2(thf)2] (Cp*=C5Me5, C5Me4H) coordinated by sterically demanding cyclopentadienyl ligands act as two-electron reductants in their reactions with DAD. These reactions occur by abstraction of one Cp* ring and result in the formation of novel YbIII mixed-ligand bent-sandwich complexes, [YbCp*(dad)(thf)], in which the dianion of DAD has an uncommon terminal ,4 -coordination to the ytterbium atom. The variable-temperature magnetic measurements of complex [Yb(C5Me5)(dad)(thf)] suggest the existence of redox tautomerism for this compound. [source] Enantiomerically Pure Titanium Complexes Containing an [OSSO]-Type Bis(phenolate) Ligand: Synthesis, Structure, and Formation of Optically Active OligostyrenesCHEMISTRY - AN ASIAN JOURNAL, Issue 8-9 2008Geert-Jan M. Meppelder Abstract Chiral 1,2- trans -dithiocyclohexanediyl-bridged bis(phenols) of the type [2,2,-{HOC6H2 -6-R1 -4-R2}2S2C6H10] ([OSSO]H2, R1=tBu, iPr, H; R2=tBu, iPr, Me) could be conveniently and selectively synthesized in three steps, starting from cyclohexene oxide and arene thiolate. The racemic bis(phenols) could be resolved using an enantiopure (S)-camphorsulfonic ester auxiliary or by (chiral) HPLC. Complexation of the racemic bis(phenols) to TiX4 (X=Cl, OiPr) proceeds in a diastereoselective fashion to give only the ,,R,R and ,,S,S enantiomers. Racemic [Ti{(OC6H2 -6- tBu-4-Me)2S2C6H10}Cl2] reacts with benzyl magnesium bromide to afford the crystallographically characterized dibenzyl complex. The benzyl cation formed using B(C6F5)3 in C6D5Br slowly decomposes at temperatures above +10,°C. When treated with methylaluminoxane, the dichloro complexes [Ti{OSSO}Cl2] polymerize styrene with activities up to 146,kg,(mol,catalyst),1,[styrene,(mol,L,1)],1,h,1; diisopropoxy complexes [Ti{OSSO}(OiPr)2] show mere trace activity. With 1-hexene as a chain-transfer agent, activated enantiopure titanium complexes give low-molecular-weight homochiral isotactic oligostyrenes, terminated by one to five 1-hexene units with Mn values as low as 750,g,mol,1 for R=tBu and 1290,g,mol,1 for R=Me. Below Mn,5000 these oligostyrenes show optical activity. [source] Photoinduced Energy- and Electron-Transfer Processes in Dinuclear RuII,OsII, RuII,OsIII, and RuIII,OsII Trisbipyridine Complexes Containing a Shape-Persistent Macrocyclic SpacerCHEMPHYSCHEM, Issue 1 2006Margherita Venturi Prof. Abstract The PF6,salt of the dinuclear [(bpy)2Ru(1)Os(bpy)2]4+complex, where 1 is a phenylacetylene macrocycle which incorporates two 2,2,-bipyridine (bpy) chelating units in opposite sites of its shape-persistent structure, was prepared. In acetonitrile solution, the Ru- and Os-based units display their characteristic absorption spectra and electrochemical properties as in the parent homodinuclear compounds. The luminescence spectrum, however, shows that the emission band of the RuIIunit is almost completely quenched with concomitant sensitization of the emission of the OsIIunit. Electronic energy transfer from the RuIIto the OsIIunit takes place by two distinct processes (ken=2.0×108and 2.2×107s,1at 298 K). Oxidation of the OsIIunit of [(bpy)2Ru(1)Os (bpy)2]4+by CeIVor nitric acid leads quantitatively to the [(bpy)2RuII(1)OsIII(bpy)2]5+complex which exhibits a bpy-to-OsIIIcharge-transfer band at 720 nm (,max=250,M,1cm,1). Light excitation of the RuIIunit of [(bpy)2RuII(1)OsIII(bpy)2]5+is followed by electron transfer from the RuIIto the OsIIIunit (kel,f=1.6×108and 2.7×107s,1), resulting in the transient formation of the [(bpy)2RuIII(1)OsII(bpy)2]5+complex. The latter species relaxes to the [(bpy)2RuII(1)OsIII(bpy)2]5+one by back electron transfer (kel,b=9.1×107and 1.2×107s,1). The biexponential decays of the [(bpy)2*RuII(1)OsII(bpy)2]4+, [(bpy)2*RuII(1)OsIII(bpy)2]5+, and [(bpy)2RuIII(1)OsII(bpy)2]5+species are related to the presence of two conformers, as expected because of the steric hindrance between hydrogen atoms of the pyridine and phenyl rings. Comparison of the results obtained with those previously reported for other Ru,Os polypyridine complexes shows that the macrocyclic ligand 1 is a relatively poor conducting bridge. [source] The proteasome inhibitor, MG132, promotes the reprogramming of translation in C2C12 myoblasts and facilitates the association of hsp25 with the eIF4F complexFEBS JOURNAL, Issue 17 2004Joanne L. Cowan The eukaryotic translation initiation factor (eIF) 4E, is regulated by modulating both its phosphorylation and its availability to interact with the scaffold protein, eIF4G, to form the mature eIF4F complex. Here we show that treatment of C2C12 myoblasts with the proteasomal inhibitor, MG132 (N -carbobenzoxyl-Leu-Leu-leucinal), resulted in an early decrease in protein synthesis rates followed by a partial recovery, reflecting the reprogramming of translation. The early inhibition of protein synthesis was preceded by a transient increase in eIF2, phosphorylation, followed by a sustained increase in eIF4E phosphorylation. Inhibition of eIF4E phosphorylation with CGP57380 failed to prevent translational reprogramming or the moderate decrease in eIF4F complexes at later times. Prolonged incubation with MG132 resulted in the increased expression of heat shock protein (hsp)25, ,B-crystallin and hsp70, with a population of hsp25 associating with the eIF4F complex in a p38 mitogen-activated protein kinase-dependent manner. Under these conditions, eIF4GI, and to a lesser extent eIF4E, re-localized from a predominantly cytoplasmic distribution to a more perinuclear and granular staining. Although MG132 had little effect on the colocalization of eIF4E and eIF4GI, it promoted the SB203580-sensitive association of eIF4GI and hsp25, an effect not observed with ,B-crystallin. Addition of recombinant hsp25 to an in vitro translation assay resulted in stimulation of on-going translation and a moderate decrease in de novo translation, indicating that this modified eIF4F complex containing hsp25 has a role to play in recovery of mRNA translation following cellular stress. [source] Molecular interaction of neutral trehalase with other enzymes of trehalose metabolism in the fission yeast Schizosaccharomyces pombeFEBS JOURNAL, Issue 15 2002Teresa Soto Trehalose metabolism is an essential component of the stress response in yeast cells. In this work we show that the products of the principal genes involved in trehalose metabolism in Schizosaccharomyces pombe, tps1+ (coding for trehalose-6- P synthase, Tps1p), ntp1+ (encoding neutral trehalase, Ntp1p) and tpp1+ (that codes for trehalose-6- P phosphatase, Tpp1p), interact in vitro with each other and with themselves to form protein complexes. Disruption of the gene tps1+ blocks the activation of the neutral trehalase induced by heat shock but not by osmotic stress. We propose that this association may reflect the Tps1p-dependent requirement for thermal activation of trehalase. Data reported here indicate that following a heat shock the enzyme activity of trehalase is associated with Ntp1p dimers or trimers but not with either Ntp1p monomers or with complexes involving Tps1p. These results raise the possibility that heat shock and osmotic stress activate trehalase differentially by acting in the first case through an specific mechanism involving Tps1p,Ntp1p complexes. This study provides the first evidence for the participation of the catabolic enzyme trehalase in the structural framework of a regulatory macromolecular complex containing trehalose-6- P synthase in the fission yeast. [source] The treatment of solvation by a generalized Born model and a self-consistent charge-density functional theory-based tight-binding methodJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2002Li Xie Abstract We present a model to calculate the free energies of solvation of small organic compounds as well as large biomolecules. This model is based on a generalized Born (GB) model and a self-consistent charge-density functional theory-based tight-binding (SCC-DFTB) method with the nonelectrostatic contributions to the free energy of solvation modeled in terms of solvent-accessible surface areas (SA). The parametrization of the SCC-DFTB/GBSA model has been based on 60 neutral and six ionic molecules composed of H, C, N, O, and S, and spanning a wide range of chemical groups. Effective atomic radii as parameters have been obtained through Monte Carlo Simulated Annealing optimization in the parameter space to minimize the differences between the calculated and experimental free energies of solvation. The standard error in the free energies of solvation calculated by the final model is 1.11 kcal mol,1. We also calculated the free energies of solvation for these molecules using a conductor-like screening model (COSMO) in combination with different levels of theory (AM1, SCC-DFTB, and B3LYP/6-31G*) and compared the results with SCC-DFTB/GBSA. To assess the efficiency of our model for large biomolecules, we calculated the free energy of solvation for a HIV protease-inhibitor complex containing 3204 atoms using the SCC-DFTB/GBSA and the SCC-DFTB/COSMO models, separately. The computed relative free energies of solvation are comparable, while the SCC-DFTB/GBSA model is three to four times more efficient, in terms of computational cost. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 1404,1415, 2002 [source] Poly[[diaqua(,3 -2,2-dimethylmalonato)cadmium(II)] tetrahydrate]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009Ming-Lin Guo In the title complex, {[Cd(C5H6O4)(H2O)2]·4H2O}n, the dimethylmalonate,cadmium metal,organic framework co-exists with an extended structure of water molecules, which resembles a sodalite-type framework. In the asymmetric unit, there are five independent solvent water molecules, two of which are in special positions. The Cd atoms are eight-coordinated in a distorted square-antiprismatic geometry by six O atoms of three different dimethylmalonate groups and by two water molecules, and form a two-dimensional honeycomb layer parallel to the bc plane. Two such layers sandwich the hydrogen-bonded water layer, which has a sodalite-type structure with truncated sodalite units composed of coordinated and solvent water molecules. This work is the first example of a dimethylmalonate cadmium complex containing truncated sodalite-type water clusters. [source] | ||||||||||||||||||||||