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1.
Kojima T Morimoto T Sakamoto T Miyazaki S Fukuzumi S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(29):8904-8915
Ruthenium(II)-TPA-diimine complexes, [Ru(TPA)(diimine)]2+ (TPA=tris(2-pyridylmethyl)amine; diimine=2,2'-bipyridine (bpy), 2,2'-bipyrimidine (bpm), 1,10-phenanthroline (phen)) were synthesized and characterized by spectroscopic and crystallographic methods. Their crystal structures demonstrate severe steric hindrance between the TPA and diimine ligands. They exhibit drastic structural changes on heating and photoirradiation at their MLCT bands, which involve partial dissociation of the tetradentate TPA ligand to exhibit a facially tridentate mode accompanied by structural change and solvent coordination to give [Ru(TPA)(diimine)(solvent)]2+ (solvent=acetonitrile, pyridine). The incoming solvent molecules are required to have pi-acceptor character, since sigma-donating solvent molecules do not coordinate. The thermal process is irreversible dissociation to give the solvent-bound complexes, which takes place by an interchange associative mechanism with large negative activation entropies. The photochemical process is a reversible reaction reaching a photostationary state, probably by a dissociative mechanism involving a five-coordinate intermediate to afford the same product as obtained in the thermal reaction. Quantum yields of the forward reactions to give dissociated products were lower than those of the backward reactions to recover the starting complexes. In the photochemical process, the conversions of the forward and backward reactions depend on the absorption coefficients of the starting materials and those of the products at certain wavelength, as well as the quantum yields of those reactions. The reversibility of the motions can be regulated by heating and by photoirradiation at certain wavelength for the recovery process. In the bpm system, we could achieve about 90 % recovery in thermal/photochemical structural interconversion. 相似文献
2.
Stadler AM Puntoriero F Campagna S Kyritsakas N Welter R Lehn JM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(13):3997-4009
The isomeric bis(tridentate) hydrazone ligand strands 1 a-c react with [Ru(terpy)Cl3] (terpy=2,2':6',2'-terpyridine) to give dinuclear rack-type compounds 2 a-c, which were characterised by several techniques, including X-ray crystallography and NMR methods. The absorption spectra, redox behaviour and luminescence properties (both in fluid solution at room temperature and in rigid matrix at 77 K) of the ligand strands 1 a-c and of the metal complexes 2 a-c have been studied. Compounds 1 a-c exhibit absorption spectra dominated by intense pi-pi* bands, which, in the case of 1 b and 1 c, extend within the visible region, while the absorption spectra of the rack-type complexes 2 a-c show intense bands both the in the UV region, due to spin-allowed ligand-centred (LC) transitions, and in the visible, due to spin-allowed metal-to-ligand charge-transfer (MLCT) transitions. The energy position of these bands strongly depends on the ligand strand: in the case of 2 a, the lowest energy MLCT band is around 470 nm, while in 2 b and 2 c, it lies beyond 600 nm. Ligands 1 a-c undergo oxidation processes that involve orbitals based mainly on the CH3--N--N== fragments. The complexes 2 a-c undergo reversible metal-centred oxidation, while reductions involve the hydrazone-based ligands: in 2 b and 2 c, the bridging ligand is reduced twice and in 2 a once before reduction of the peripheral terpy ligands takes place. Ligands 1 a-c exhibit luminescence from the lowest-lying 1pi-pi* level. Only for complex 2 a does emission occur; this may be attributed to a 3MLCT state involving the bridging ligand. Taken together, the results clearly indicate that the structural variations introduced translate into interesting differences in the spectroscopic, luminescence and redox properties of the ligand strands as well as of the rack-type metal complexes. 相似文献
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Ishizuka T Sawaki T Miyazaki S Kawano M Shiota Y Yoshizawa K Fukuzumi S Kojima T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(24):6652-6662
The pterin‐coordinated ruthenium complex, [RuII(dmdmp)(tpa)]+ ( 1 ) (Hdmdmp=N,N‐dimethyl‐6,7‐dimethylpterin, tpa=tris(2‐pyridylmethyl)amine), undergoes photochromic isomerization efficiently. The isomeric complex ( 2 ) was fully characterized to reveal an apparent 180° pseudorotation of the pterin ligand. Photoirradiation to the solution of 1 in acetone with incident light at 460 nm resulted in dissociation of one pyridylmethyl arm of the tpa ligand from the RuII center to give an intermediate complex, [Ru(dmdmp)(tpa)(acetone)]2+ ( I ), accompanied by structural change and the coordination of a solvent molecule to occupy the vacant site. The quantum yield (?) of this photoreaction was determined to be 0.87 %. The subsequent thermal process from intermediate I affords an isomeric complex 2 , as a result of the rotation of the dmdmp2? ligand and the recoordination of the pyridyl group through structural change. The thermal process obeyed first‐order kinetics, and the rate constant at 298 K was determined to be 5.83×10?5 s?1. The activation parameters were determined to be ΔH≠=81.8 kJ mol?1 and ΔS≠=?49.8 J mol?1 K?1. The negative ΔS≠ value indicates that this reaction involves a seven‐coordinate complex in the transition state (i.e., an interchange associative mechanism). The most unique point of this reaction is that the recoordination of the photodissociated pyridylmethyl group occurs only from the direction to give isomer 2 , without going back to starting complex 1 , and thus the reaction proceeds with 100 % conversion efficiency. Upon heating a solution of 2 in acetonitrile, isomer 2 turned back into starting complex 1 . The backward reaction is highly dependent on the solvent: isomer 2 is quite stable and hard to return to 1 in acetone; however, 2 was converted to 1 smoothly by heating in acetonitrile. The activation parameters for the first‐order process in acetonitrile were determined to be ΔH≠=59.2 kJ mol?1 and ΔS≠=?147.4 kJ mol?1 K?1. The largely negative ΔS≠ value suggests the involvement of a seven‐coordinate species with the strongly coordinated acetonitrile molecule in the transition state. Thus, the strength of the coordination of the solvent molecule to the RuII center is a determinant factor in the photoisomerization of the RuII–pterin complex. 相似文献
5.
Díez-González S Stevens ED Scott NM Petersen JL Nolan SP 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(1):158-168
The preparation of two series of [Cu(NHC)2]X complexes (NHC=N-heterocyclic carbene, X=PF6 or BF4) in high yields from readily available materials is reported. These complexes have been spectroscopically and structurally characterized. The activity of these cationic bis-NHC complexes in the hydrosilylation of ketones was examined, and both the ligand and the counterion showed a significant influence on the catalytic performance. Moreover, when compared with related [Cu(NHC)]-based systems, these cationic complexes proved to be more efficient under similar reaction conditions. The activation step of [Cu(NHC)2]X precatalysts towards hydrosilylation was investigated by means of 1H NMR spectroscopy. Notably, it was shown that one of the N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) ligands in [Cu(IPr)2]BF4 is displaced by tBuO(-) in the presence of NaOtBu, producing the neutral [Cu(IPr)(OtBu)]. This copper alkoxide is known to be a direct precursor of an NHC-copper hydride, the actual active species in this transformation. Furthermore, reagent loading and counterion effects have been rationalized in light of the species formed during the reaction. 相似文献
6.
《Journal of Coordination Chemistry》2012,65(12):1279-1289
This article describes the preparation and characterization of cis-[Ru(bipy)2L](ClO4)2 and trans-[RuCl2L2]?·?Cl (bipy?=?2,2′-bipyridyl and L?=?ortho-phenylenediamine (o-phd), 2-aminopyridine (2-apy) and 2-aminobenzonitrile (2-abn), and examines the catalytic oxidations of benzyl alcohol, benzohydrol and pipronyl alcohol by cis-[Ru(bipy)2 (o-phd)](ClO4)2 and trans-[RuCl2(o-phd)2]?·?Cl complexes at room temperature and in the presence of N-methyl morpholine-N-oxide (NMO) as co-oxidant. 相似文献
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Stable ruthenium(II) carbonyl complexes of the type [RuCl(CO)(EPh3)(B)(L)] (E = P or As; B = PPh3, AsPh3 or Py; L = 2′‐hydroxychalcones) were synthesized from the reaction of [RuHCl(CO)(EPh3)2(B)] (E = P or As; B = PPh3, AsPh3 or Py) with 2′‐hydroxychalcones in benzene under reflux. The new complexes were characterized by analytical and spectroscopic (IR, electronic 1H, 31P and 13C NMR) data. They were assigned an octahedral structure. The complexes exhibited catalytic activity for the oxidation of primary and secondary alcohols into their corresponding aldehydes and ketones in the presence of N‐methylmorpholine‐N‐oxide (NMO) as co‐oxidant and were also found to be efficient transfer hydrogenation catalysts. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
9.
Seiler O Burschka C Metz S Penka M Tacke R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(24):7379-7386
The neutral pentacoordinate silicon(IV) complexes 8 and 9 with an SiO2N3 skeleton and the neutral hexacoordinate silicon(IV) complex 10.1/2 CH3CN with an SiO4N2 skeleton were synthesized, starting from tetra(cyanato-N)silane or tetra(thiocyanato-N)silane. Compounds 8 and 9 contain one tridentate dianionic ligand derived from 4-[(2-hydroxyphenyl)amino]pent-3-en-2-one and two monodentate singly charged cyanato-N or thiocyanato-N ligands bound to the silicon(IV) coordination center, whereas the silicon(IV) center of 10 is coordinated by two of these tridentate dianionic ligands. All compounds were characterized by single-crystal X-ray diffraction and solid-state and solution NMR spectroscopy. To get more information about the stereochemistry of the compounds studied, the experimental investigations were complemented by computational studies. 相似文献
10.
《Journal of Coordination Chemistry》2012,65(14):2523-2534
Dinuclear arene ruthenium complexes [(η6-arene)Ru(μ-Cl)Cl]2 (arene?=?C6H6; p iPrC6H4Me; C6Me6) and monomeric cyclopentadienyl complexes [(η5-Cp)Ru(PPh3)2Cl] (Cp?=?cyclopentadienyl) react with polypyridyl nitrogen ligands L1 (3-(pyridin-2-yl)-1H-1,2,4-triazole) and L2 (1,3-bis(di-2-pyridylaminomethyl)benzene) in methanol to afford cationic mononuclear compounds [(η6-arene)Ru(L1)Cl]+ (arene?=?C6H6, 1; p iPrC6H4Me, 2; C6Me6, 3), [(η6arene)Ru(L2)Cl]+ (arene?=?C6H6, 4; p iPrC6H4Me, 5; C6Me6, 6), [(η5-Cp)Ru(L1)(PPh3)]+ (7), and [(η5Cp)Ru(L2)(PPh3)]+ (8). All cationic mononuclear compounds were isolated as their hexafluorophosphate salts and characterized by elemental analyses, NMR, and IR spectroscopic methods and some representative complexes by UV-Vis spectroscopy. The solid state structures of two derivatives, [6]PF6 and [7]PF6, have been determined by the X-ray structure analysis. 相似文献
11.
Peacock AF Melchart M Deeth RJ Habtemariam A Parsons S Sadler PJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(9):2601-2613
Density functional calculations show that aquation of [Os(eta6-arene)(XY)Cl]n+ complexes is more facile for complexes in which XY=an anionic O,O-chelated ligand compared to a neutral N,N-chelated ligand, and the mechanism more dissociative in character. The O,O-chelated XY=maltolato (mal) [M(eta6-p-cym)(mal)Cl] complexes, in which p-cym=p-cymene, M=OsII (1) and RuII (2), were synthesised and the X-ray crystal structures of 1 and 22 H2O determined. Their hydrolysis rates were rapid (too fast to follow by NMR spectroscopy). The aqua adduct of the OsII complex 1 was 1.6 pKa units more acidic than that of the RuII complex 2. Dynamic NMR studies suggested that O,O-chelate ring opening occurs on a millisecond timescale in coordinating proton-donor solvents, and loss of chelated mal in aqueous solution led to the formation of the hydroxo-bridged dimers [(eta6-p-cym)M(mu-OH)3M(eta6-p-cym)]+. The proportion of this dimer in solutions of the OsII complex 1 increased with dilution and it predominated at micromolar concentrations, even in the presence of 0.1 M NaCl (conditions close to those used for cytotoxicity testing). Although 9-ethylguanine (9-EtG) binds rapidly to Os(II) in 1 and more strongly (log K=4.4) than to RuII in 2 (log K=3.9), the OsII adduct [Os(eta6-p-cym)(mal)(9EtG)]+ was unstable with respect to formation of the hydroxo-bridged dimer at micromolar concentrations. Such insights into the aqueous solution chemistry of metal-arene complexes under biologically relevant conditions will aid the rational design of organometallic anticancer agents. 相似文献
12.
Natarajan Thilagavathi Chinnasamy Jayabalakrishnan 《Central European Journal of Chemistry》2010,8(4):842-851
Ru(III) complexes of the type [RuXB(L)2] have been prepared by the reaction of 3,4-dihydropyrimidin-2(1H)-ones/thiones (HL1–HL4) with the precursors of the type [RuX3B3] where X=Cl or Br; B=PPh3 or AsPh3 and L is the deprotonated ligand. The synthesized complexes were characterized by physico-chemical methods, electrochemical
and magnetic moment data. The catalytic efficiency of the complexes were examined in the oxidation of alcohols and antimicrobial
studies were also carried out.
相似文献
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Urmila Pal Chaudhuri Lei Yang Laura R. Whiteaker Arunendu Mondal Matthew R. Fultz Douglas R. Powell Robert P. Houser 《Polyhedron》2007,26(18):5420-5431
Mononuclear copper(II) complexes of a family of pyridylmethylamide ligands HL, HLMe, HLPh, HLMe3 and HLPh3, [HL = N-(2-pyridylmethyl)acetamide; HLMe = N-(2-pyridylmethyl)propionamide; HLPh = 2-phenyl-N-(2-pyridylmethyl)acetamide; HLMe3 = 2,2-dimethyl-N-(2-pyridylmethyl)propionamide; HLPh3 = 2,2,2-triphenyl-N-(2-pyridylmethyl)acetamide], were synthesized and characterized. The reaction of copper(II) salts with the pyridylmethylamide ligands yields complexes [Cu(HL)2(OTf)2] (1), [Cu(HLMe)2](ClO4)2 (2), [Cu(HL)2Cl]2[CuCl4] (3), [Cu(HLMe3)2(THF)](OTf)2 (4), [Cu(HLMe3)2(H2O)](ClO4)2 (5a and 5b), [Cu(HLPh3)2(H2O)](ClO4)2 (6), [Cu(HL)(2,2′-bipy)(H2O)](ClO4)2 (7), and [Cu(HLPh)(2,2′-bipy)(H2O)](ClO4)2 (8). All complexes were fully characterized, and the X-ray structures vary from four-coordinate square-planar, to five-coordinate square-pyramidal or trigonal-bipyramidal. The neutral ligands coordinate via the pyridyl N atom and carbonyl O atom in a bidentate fashion. The spectroscopic properties are typical of mononuclear copper(II) species with similar ligand sets, and are consistent their X-ray structures. 相似文献
15.
Meiners J Scheibel MG Lemée-Cailleau MH Mason SA Boeddinghaus MB Fässler TF Herdtweck E Khusniyarov MM Schneider S 《Angewandte Chemie (International ed. in English)》2011,50(35):8184-8187
Squaring the circle: the novel dienamido pincer ligand N(CHCHPtBu(2))(2)(-) affords the isolation of the unusual square-planar iridium(II) and iridium(III) amido complexes [IrCl{N(CHCHPtBu(2))(2)}](n) (n=0 (1), +1 (2)). In contrast, the corresponding iridium(I) complex of the redox series (n=-1) is surprisingly unstable. The diamagnetism of 2 is attributed to strong N→Ir π donation. 相似文献
16.
Fernández R Melchart M Habtemariam A Parsons S Sadler PJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(20):5173-5179
We show that the chelating ligand XY in Ru(II) anticancer complexes of the type [Ru(eta6-arene)(XY)Cl]n+ has a major influence on the rate and extent of aquation, the pKa of the aqua adduct, and the rate and selectivity of binding to nucleobases. Replacement of neutral ethylenediamine (en) by anionic acetylacetonate (acac) as the chelating ligand increases the rate and extent of hydrolysis, the pKa of the aqua complex (from 8.25 to 9.41 for arene=p-cymene), and changes the nucleobase specificity. For the complexes containing the hydrogen-bond donor en, there is exclusive binding to N7 of guanine in competitive nucleobase reactions, and in the absence of guanine, binding to cytosine or thymine but not to adenine. In contrast, when XY is the hydrogen-bond acceptor acac, the overall affinity for adenosine (N7 and N1 binding) is comparable to that for guanosine, but there is little binding to cytidine or thymidine. 相似文献
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《Journal of Coordination Chemistry》2012,65(6):923-930
A mononuclear ruthenium(III) complex containing ethylenediaminetetraacetate (edta), [Ru(Hedta)(Htrz)] · 4H2O (1) (Htrz = 1H-1,2,4-triazole), has been synthesized and the structure was determined by single-crystal X-ray diffraction. The complex crystallizes in the triclinic space group P 1, with the unit cell parameters a = 7.212(3) Å, b = 9.873(4) Å, c = 13.806(6) Å, α = 91.945(6)°, β = 100.078(6)°, γ = 97.230(7) and Z = 2. The complex was also characterized by elemental analysis, IR, UV–Vis and ESR spectra. Cyclic voltammetry for the complex shows a ruthenium(III)/ruthenium(IV) oxidation and a ruthenium(III)/ruthenium(II) reduction within the range of ?1.5–0.5 V. Magnetic susceptibility data give an effective moment of 1.81 B.M. at room temperature. 相似文献
19.
Vicinal carbonyl oxime (HL1) and oxime-imine (H2L2) ligands and their mononuclear Ru(III) and Cu(II), heterodinuclear Ru(III)-Mn(II), Ru(III)-Ni(II), Ru(III)-Cu(II), and heterotrinuclear
Ru(III)-Cu(II)-Ru(III) chelates were synthesized and characterized by elemental analysis, molar conductivity, IR, ESR, ICP-OES,
magnetic moment measurements, and thermal analyses studies. The free ligands were also characterized by 1H NMR spectra. The carbonyl-oxime ligand coordinates through the oxygen of =N-OH to form a six-membered chelate ring. The
quadridentate tetraaza ligand (H2L2) obtained by condensing of the bidentate ligand 1-p-diphenylmethane-2-hydroxyimino-2-(1-naphthylamino)-1-ethanone (HL1) with 1,2-phenylenediamine coordinates with Ru(III) through its nitrogen donors in the equatorial position with the loss
of one of the oxime protons and concomitant formation of an intramolecular hydrogen bond. Stoichiometric and spectral results
of the metal complexes indicated that the metal: ligand ratios in the mononuclear complexes of the ligand (HL1) were found to be 1: 2, while these ratios were 1: 1 in the mononuclear complexes of the ligand (H2L2). The metal: ligand ratios of the dinuclear complexes were found to be 2: 1, and this ratio was 3: 2 in the trinuclear complex.
The article is published in the original. 相似文献
20.
Several new symmetrical aromatic hydrocarbon bridged bipyridine ligands and their binuclear Ru (II) complexes have been designed, synthesized and characterized on the basis of 1H NMR, MS and HRMS. Their absorption and emission properties, electrochemical behaviors and electrochemical luminescence were investigated. All ruthenium complexes show characteristic MLCT absorption and similar redox potential. Among the three complexes reported, 4c has the best electrochemical luminescence property. 相似文献