Oligothiophene-2-yl-vinyl bridged mono- and binuclear ruthenium(II) tris-bipyridine complexes: Synthesis, photophysics, electrochemistry and electrogenerated chemiluminescence

A series of mono- and binuclear ruthenium(II) tris-bipyridine complexes tethered to oligothienylenevinylenes have been synthesized and characterized by ¹H NMR, ¹³C NMR and TOF-MS spectrometry. Photophysics, electrochemistry and electrogenerated chemiluminescence (ECL) properties of these complexes are investigated. The electronic absorption spectra of the mononuclear ruthenium complexes show a significant red shift both at MLCT (metal-to-ligand charge transfer) and π-π^∗ transitions of oligothienylenevinylenes with increase in the number of thiophenyl-2-yl-vinyl unit. For the binuclear complexes these two absorption bands are overlapped. All the metal complexes have very weak emission compared to that of the reference complex Ru(bpy)²⁺₃. The first reduction potentials of all mononuclear ruthenium complexes are less negative than that of Ru(bpy)²⁺₃, due to the moderate electron-withdrawing effect of oligothienylenevinylenes. For binuclear ruthenium complexes, only one Ru(II/III) oxidation peak (E_1/2 = 0.96 V vs. Ag/Ag⁺) was observed, suggesting a weak interaction between two metal centers. Three successive reduction processes of bipyridine ligands are similar among all ruthenium complexes except for RuTRu, which has a very sharp peak owing to the accumulation of neutral product on the electrode surface. All these ruthenium complexes exhibited different ECL property in CH₃CN solution without any additional reductant or oxidant. For three mononuclear ruthenium complexes, the ECL intensity strengthens with increase in the number of thiophene-2-yl-vinyl unit. However, the ECL efficiency dramatically decreased in the binuclear ruthenium complexes. The ECL efficiencies of all the reported complexes do not exceed that of Ru(bpy)²⁺₃, where the ECL efficiency decreases in the order of RuTRu > Ru3T > Ru2T > RuT > Ru2TRu (RuT,bis-2,2′-bipyridyl-(4-methyl-4′-(2-thienylethenyl)-2,2′-bipyridine) ruthenium dihexafluorophosphate; Ru2T, bis-2,2′-bipyridyl-(4-methyl-4′-{(E)-2-[5-((E)-2-thienylethenyl)-thienylethenyl]}-2,2′-bipyridine) ruthenium dihexafluorophosphate; Ru3T, bis-2,2′-bipyridyl-(4-methyl-4′-{(E)-2-{(E)-2-[5-((E)-2-thienylethenyl)-thienylethenyl]}}-2,2′-bipyridine) ruthenium dihexafluorophosphate; RuTRu, bis-2,2′-bipyridyl-ruthenium-bis-[2-((E)-4′-methyl-2, 2′-bipyridinyl-4)-ethenyl]-thienyl-bis-2,2′-bipyridyl-ruthenium tetrahexafluorophosphate; Ru2TRu, bis-2,2′-bipyridyl-ruthenium-(E)-1,2-bis-{2-[2-((E)-4′-methyl-2,2′-bipyridinyl-4)-ethenyl]-thienyl}-ethenyl-bis-2,2′-bipyridyl-ruthenium tetrahexafluorophosphate).     

系列双核Ln(III)配合物的晶体结构和磁性

合成了分子式为[Ln~2(phen)~2L],phen=C~1~2H~8N~2[ALn=Nd,L=(CH~3COO)~4(ONO~2)~2,BLn=Sm,L=(C~6H~5COO)~6,CLn=Eu,L=(C~6H~5COO)~6]3种同双核配合物。用X射线四圆衍射仪测定了3种化合物的结构。在化合物A分子中,2个Nd(III)原子由4个CH~3COO^-基团桥联,以phen和ONO~2^-为端基,构成了一个具有C~2对称性的双核分子。配合物B和C具有完全相同的结构,它们是以4个苯甲酸根为桥,2个phen和2个C~6H~5COO^-为端基的中心对称双核分子,其中6个苯甲酸根的成键状态可分为3种状况。在3种化合物中,每个Ln均为9配位,呈不规则多面体。Ln-Ln距离,A为0.397nm,B和C均为0.405nm。测定了各配合物的变温磁化率,通过对磁性质研究,发现化合物A在低温下具有反铁磁物质行为,并由理论拟合,求得了磁参数g,J值。     

系列双核Ln(III)配合物的晶体结构和磁性

合成了分子式为[Ln~2(phen)~2L],phen=C~1~2H~8N~2[ALn=Nd,L=(CH~3COO)~4(ONO~2)~2,BLn=Sm,L=(C~6H~5COO)~6,CLn=Eu,L=(C~6H~5COO)~6]3种同双核配合物。用X射线四圆衍射仪测定了3种化合物的结构。在化合物A分子中,2个Nd(III)原子由4个CH~3COO^-基团桥联,以phen和ONO~2^-为端基,构成了一个具有C~2对称性的双核分子。配合物B和C具有完全相同的结构,它们是以4个苯甲酸根为桥,2个phen和2个C~6H~5COO^-为端基的中心对称双核分子,其中6个苯甲酸根的成键状态可分为3种状况。在3种化合物中,每个Ln均为9配位,呈不规则多面体。Ln-Ln距离,A为0.397nm,B和C均为0.405nm。测定了各配合物的变温磁化率,通过对磁性质研究,发现化合物A在低温下具有反铁磁物质行为,并由理论拟合,求得了磁参数g,J值。     

Bis(acetylacetonato)ruthenium(II) complexes containing alkynyldiphenylphosphines. Formation and redox behaviour of [Ru(acac)2(Ph2PC triple bond CR)2] (R=H, Me, Ph) complexes and the binuclear complex cis-[{Ru(acac)2}2(micro-Ph2PC triple bond CPPh2)}2

Two equivalents of Ph(2)PC triple bond CR (R=H, Me, Ph) react with thf solutions of cis-[Ru(acac)(2)(eta(2)-alkene)(2)] (acac=acetylacetonato; alkene=C(2)H(4), 1; C(8)H(14), 2) at room temperature to yield the orange, air-stable compounds trans-[Ru(acac)(2)(Ph(2)PC triple bond CR)(2)] (R=H, trans-3; Me=trans-4; Ph, trans-5) in isolated yields of 60-98%. In refluxing chlorobenzene, trans-4 and trans-5 are converted into the yellow, air-stable compounds cis-[Ru(acac)(2)(Ph(2)PC triple bond CR)(2)] (R=Me, cis-4; Ph, cis-5), isolated in yields of ca. 65%. From the reaction of two equivalents of Ph(2)PC triple bond CPPh(2) with a thf solution of 2 an almost insoluble orange solid is formed, which is believed to be trans-[Ru(acac)(2)(micro-Ph(2)PC triple bond CPPh(2))](n) (trans-6). In refluxing chlorobenzene, the latter forms the air-stable, yellow, binuclear compound cis-[{Ru(acac)(2)(micro-Ph(2)PC triple bond CPPh(2))}(2)] (cis-6). Electrochemical studies indicate that cis-4 and cis-5 are harder to oxidise by ca. 300 mV than the corresponding trans-isomers and harder to oxidise by 80-120 mV than cis-[Ru(acac)(2)L(2)] (L=PPh(3), PPh(2)Me). Electrochemical studies of cis-6 show two reversible Ru(II/III) oxidation processes separated by 300 mV, the estimated comproportionation constant (K(c)) for the equilibrium cis-6(2+) + cis6 <=> 2(cis-6(+)) being ca. 10(5). However, UV-Vis spectra of cis-6(+) and cis-6(2+), generated electrochemically at -50 degrees C, indicate that cis-6(+) is a Robin-Day Class II mixed-valence system. Addition of one equivalent of AgPF(6) to trans-3 and trans-4 forms the green air-stable complexes trans-3 x PF(6) and trans-4 x PF(6), respectively, almost quantitatively. The structures of trans-4, cis-4, trans-4 x PF(6) and cis-6 have been confirmed by X-ray crystallography.     

Crystal and molecular structures of binuclear complexes of salycilic acid {Cu-M} (M = Cu, Sr, Ba)

Heterometallic complexes [CuSr(SalH)₄(DMAA)₄(H₂O)] (II) and [CuBa(SalH)₄(DMAA)₄ (H₂O)] (III) were synthesized by interaction of salicylates of s elements with copper nitrate. A mixture of III and vanadyl sulfate yielded the crystals of a homonuclear complex [CuCu(SalH)₄(H₂O)₂]·2DMAA (I). According to single crystal X-ray data, all of the products are of lantern type and belong to two space groups: I is triclinic, space group P-1, unit cell parameters a = 9.9083(2) Å, b = 10.5077(3) Å, c = 10.9512(3) Å, α = 112.736(2)°, β = 114.0800(10)°, γ = 93.131°; II and III are tetragonal, space group P4/n, lattice parameters a = b = 16.3180(3) Å, c = 8.7838(2) Å for II and a = b = 16.362(3) Å, c = 8.920(1) Å III. The copper atoms have a square-pyramidal environment. The coordination number of Sr and Ba is 8, and the coordination polyhedron can be represented as a Thomson cube in both cases. The carboxylic groups are coordinated in a syn-syn bridging mode. The oxygen atom of the hydroxyl group of salicylic acid is not involved in coordination, but forms intramolecular hydrogen bonds to the carboxylic groups. The hydrogen bonds between water and DMAA solvate molecules, as well as — interactions between the aromatic fragments of the dimers, play a particularly important role in the molecular packing in crystal.     

Oxo-bridged metal carbene complexes. Synthesis,structure and reactivities of [[Os(Por)(CPh2)]2]O (Por = porphyrinato dianion)

Dinuclear mu-oxo osmium porphyrins containing terminal Os=CPh2 bonds with a linear C=Os-O-Os=C moiety were prepared, which are reactive toward pyridine to form [Os(Por)(CPh2)(py)] and are active catalysts for inter- and intra-molecular cyclopropanation of alkenes and for carbene insertion into saturated C-H bonds.     

Valence-state alternatives in diastereoisomeric complexes [(acac)2Ru(mu-QL)Ru(acac)2]n (QL2- = 1,4-dioxido-9,10-anthraquinone,n = +2, +1, 0, -1, -2)

The title complexes were obtained in neutral form (n = 0) as rac (1) and meso isomers (2). 2 was crystallized for X-ray diffraction and its temperature-dependent magnetism studied. It contains two antiferromagnetically coupled ruthenium(III) ions, bridged by the quinizarine dianion QL(2-) (quinizarine = 1,4-dihydroxy-9,10-anthraquinone). The potential of both the ligand (QLo --> QL4-) and the metal complex fragment combination [(acac)2RuII]2 --> ([(acac)2RuIV]2)4+ to exist in five different redox states creates a large variety of combinations, which was assessed for the electrochemically reversibly accessible 2+, 1+, 0, 1-, 2- forms using cyclic voltammetry as well as EPR and UV-vis-NIR spectroelectrochemistry. The results for the two isomers are similar: Oxidation to 1+ or 2+ causes the emergence of a near-infrared band (1390 nm), without revealing an EPR response even at 4 K. Reduction to 1- or 2- produces an EPR signal, signifying metal-centered spin but no near-infrared absorption. Tentatively, we assume metal-based oxidation of [(acac)2RuIII(mu-QL2-)RuIII(acac)2] to a mixed-valent intermediate [(acac)2RuIII(mu-QL2-)RuIV(acac)2]+ and ligand-centered reduction to a radical complex [(acac)2RuIII(mu-QL.3-)RuIII(acac)2 (-) with antiferromagnetic three-spin interaction.     

Aryl-diamide bridged binuclear ruthenium (II) tris(bipyridine) complexes: Synthesis, photophysical, electrochemical and electrochemiluminescence properties

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.     

Synthesis,characterization, electrochemistry,catalytic, and antimicrobial studies of ruthenium(III) complexes containing ONO donor ligands

A series of ruthenium(III) complexes [RuX(EPh₃)₂L] (where X = Cl or Br; E = P or As; L = deprotonated dibasic tridentate ligand) were prepared by the reaction of [RuX₃(EPh₃)₃] with Schiff bases (H₂L¹–H₂L⁴). The ligands were prepared by the condensation of N-4 phenyl/methyl semicarbazide with o-vanillin/o-hydroxy acetophenone. The complexes were characterized by elemental, physico-chemical, and electrochemical methods. Catalytic studies of these complexes for the oxidation of alcohols and aryl–aryl coupling were carried out. Antimicrobial experiments were also carried out.     

Synthesis, electrochemistry, and photophysical properties of binuclear ruthenium(II)-terpyridine complexes comprising redox-active ferrocenyl spacer

In attempting to perturb the electronic properties of the spacer, we now describe an interesting example of Ru²⁺-tpy (tpy = terpyridine) complexes with 1,1′-bis(ethynyl)polyferrocenyl moiety attached directly to the 4′-position of the tpy ligand (tpy-CC-(fc)_n-CC-tpy; fc = ferrocenyl;n = 2-3). Complexes of Ru²⁺-tpy have room-temperature luminescence in H₂O/CH₃CN (4/1) solution. The ground-state HOMO and LUMO energies were probed by electrochemical measurements and the excited-state photophysical properties were probed by UV-Vis absorption spectroscopy and luminescence spectroscopy. The redox behavior of [(tpy)Ru^II-tpy-CC-(fc)_n-CC-tpy-Ru^II(tpy)]⁴⁺ complex is dominated by the Ru²⁺/Ru³⁺ redox couple (E_1/2 from 1.35 to 1.39 V), Fe²⁺/Fe³⁺ redox couples (E_1/2 from 0.4 to 1.0 V) and tpy/tpy⁻/tpy²⁻ redox couples (E_1/2 from −1.3 to −1.5 V). Electrochemical data, UV absorption and emission spectra indicate that the π-delocalization in the spacer is enhanced by the insertion of ethynyl unit. Interestingly, the insertion of ethynyl unit into the main chain causes a dramatic increase of phosphorescence yield (1.48 × 10⁻⁴ for n = 2; 1.13 × 10⁻⁴ for n = 3), triplet lifetime (67 ns for n = 2; 24 ns for n = 3), and emission intensity. The biferrocenyl spacer can be converted into mixed-valence biferrocenium spacer, which gives a more effective π-delocalization along main chain, by selective chemical oxidation of ferrocenyl unit. In deoxygenated H₂O/CH₃CN (4/1) solution at 25 °C, the oxidized complex of [(tpy)Ru^II-tpy-CC-(fc)₂-CC-tpy-Ru^II(tpy)]⁵⁺ is nonemissive. The presence of lower energy ferrocenium-centered excited-state provides an additional channel for excited-state decay. The mixed-valence biferrocenium center acts as an efficient quencher for the MLCT excited-state.     

Syntheses,characterizations, and antimicrobial activities of binuclear ruthenium(III) complexes containing 2-substituted benzimidazole derivatives

Binuclear ruthenium(III) complexes [RuX₃L]₂?·?nH₂O (X?=?Cl, L?=?L¹, L², L³; n?=?1, L⁴ and L⁵, X?=?Br; L?=?L³), [RuX₃L_1.5]₂?·?nH₂O (X?=?Br, L?=?L¹; n?=?0, L⁴; n?=?6 and L⁵; n?=?10), and [RuX₃L₂]₂ (X?=?Br, L?=?L²) have been isolated by treatment of hydrated RuX₃ (X?=?Cl/Br) in acetone with 2-(2′-aminophenylbenzimidazole) (L¹), 2-(3′-aminophenylbenzimidazole) (L²), 2-[(3′-N-salicylidinephenyl)benzimidazole] (L³), 2-(3′-pyridylbenzimidazole) (L⁴), and 2-(4′-pyridylbenzimidazole) (L⁵) in acetone. The complexes were characterized by elemental analysis, conductivity and magnetic susceptibility measurements, IR, electronic, EPR, and mass spectral studies. The complexes were dimeric; based on analytical and spectral studies, an octahedral geometry was proposed for the complexes. The synthesized complexes were screened against Gram-positive and Gram-negative bacteria and fungi.     

Reaction of Ru3(CO)12 with 1,3-diferrocenylprop-2-ene-1-one. Crystal and molecular structures of the complexes Ru3(CO)8(FcC=CHCOFc)2 and [Ru(CO)2Cl(FcC=CHCOFc)]2

The reaction of Ru₃(CO)₁₂ with 1,3-diferrocenylprop-2-en-1-one,trans-FcCH=CHCOFc (where Fc is ferrocenyl), in boiling hexane afforded the complex (2c), which was converted into (3c) upon further heating. These complexes gave the complex (4) containing two Cl-bridged oxaruthenacycles upon dissolution in CHCl₃ or CH₂Cl₂. The structures of complexes 3 and 4 were established by X-ray diffraction analysis. According to the data of¹H NMR spectroscopy, the Cl-bridged complex exists in solutions as a mixture of isomers along with the monomeric form resulting from the cleavage of the halide bridges. All interconversions of the isomers occur with the participation of the monomeric form. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1616–1623, September, 2000.     

Theoretical study on homoleptic mononuclear and binuclear ruthenium carbonyls Ru(CO) n (n= 3–5) and Ru2(CO) n (n = 8, 9)

Science China Chemistry - Homoleptic mononuclear and binuclear ruthenium carbonyls Ru(CO) n (n = 3–5) and Ru2(CO) n (n = 8,9) have been investigated using density functional theory. Sixteen...     

Synthesis and characterization of the complexes of pentane-2,4-dione with nickel(II) and cobalt(III): [Ni(acac)2].0.5CH3OH and [Co(acac)2NO3].2H2O (acac = pentane-2,4-dione)

Two mononuclear complexes, [Ni(acac)2].0.5CH3OH (1) and[Co(acac)2NO3].2H2O (2) (acac = pentane-2,4-dione), have been synthesized and characterized by single crystal X-ray analysis. Complex 1 crystallizes in the monoclinic space group P2(1)/c with a = 9.295(4), b = 11.450(5), c = 12.974(6) A, V = 1379.1(11) A(3),beta = 92.854(7), and Z = 4. Complex 2 crystallizes in the triclinic space group P(-1) with a= 8.153(9), b = 9.925(11), c = 10.355(12), V = 746.3(15) A(3), alpha = 70.530(16), beta =71.154(15), gamma = 80.698(16) and Z = 2. Complex 1 has a one-dimensional chain-like structure, which is extended by weak hydrogen contacts, while complex 2 shows a three-dimensional network structure.     

Synthesis,crystal structure and properties of di-μ2-alkoxo bridged binuclear manganese(III) Schiff base complexes

Transition Metal Chemistry - Preparation and isolation of the dimeric manganese(III) complex, [Mn2(Salpa)2(H2O)2Cl2] · 2DMF, (1), was accomplished by air oxidation of a solution containing...     

Magnetic properties of diruthenium(II,III) carboxylate compounds. Crystal structures of Ru2Cl(mu-O2CCH=CHCH=CHMe)4 and Ru2Cl(mu-O2CCH2OMe)4

The reaction of Ru2Cl(mu-O2CMe)4 with 2,4-hexadienoic and 2-methoxyacetic acids affords the compounds Ru2Cl(mu-O2CR)4 [R = CH=CHCH=CHCH3 (1), CH2OMe (2)]. The structures of both complexes have been determined by X-ray crystallography. 1 crystallizes in the triclinic space group P-1 with a = 9.264(1) A, b = 12.661(8) A, c = 12.839(5) A, alpha = 106.09(3) degrees, beta = 77.89(2) degrees, gamma = 97.73(3) degrees, and Z = 2. 2 crystallizes in the nonstandard monoclinic space group P2(1)/c with a = 12.132(4) A, b = 11.570(2) A, c = 13.674(2) A, beta = 91.18(2) degrees, and Z = 4. Complexes 1 and 2 show [Ru2(mu-O2CR)4]+ units linked by chloride ions, giving zigzag chains with Ru-Cl-Ru angles of 119.43(4) degrees and 110.11(7) degrees, respectively. The Ru-Ru bond distances are 2.2857(9) A (1) and 2.290(1) A (2). A magnetic study, in the 2-300 K temperature range, of the new compounds and the previously described Ru2Cl(mu-O2CR)4 [R = CHMe2 (3), CMe3 (4), C4H4N (5)] is described. The polymeric complexes 1 and 2 and the nonpolymeric 3-5 show a large zero-field splitting which varies from 53.9 to 68.1 cm-1. These complexes also show a weak, but not negligible, through-space intermolecular antiferromagnetic coupling not observed in the previous magnetic studies carried out on these types of compounds.     

Mononuclear manganese(III) aquo complexes. Crystal and molecular structures of [Mn(phen)(OH2)Cl3] and [Mn(acac)2-(OH2)2]ClO4·2H2O (acacH = acetylacetone,phen = 1,10-phenanthroline)

Summary The crystal and molecular structures of [Mn(phen)-(OH₂)Cl₃] (1) and [Mn(acac)₂(OH₂)₂]ClO₄·2H₂O (2) were determined. A comparison is made of the Jahn-Teller distortion in these compounds with those observed in other manganese(III) complexes with monodentate axial ligands.     

Effect of substituents on DNA-binding behaviors of ruthenium(II) complexes: [Ru(dmb)2(dtmi)]2+ and [Ru(dmb)2(dtni)]2+

Two Ru(II) complexes [Ru(dmb)₂(dtmi)](ClO₄)₂ (1) (dmb = 4, 4′-dimethyl-2, 2′-bipyridine, dtmi = 3-(pyrazin-2-yl)-as-triazino[5, 6-f]-5-methoxylisatin) and [Ru(dmb)₂(dtni)](ClO₄)₂ (2) (dtni = 3-(pyrazin-2-yl)-as-triazino[5, 6-f]-5-nitroisatin) have been synthesized and characterized by elemental analysis, ES-MS, and ¹H NMR. DNA-binding behaviors of these complexes have been investigated by spectroscopic titration, viscosity measurements, and thermal denaturation. The results indicate that the two complexes interact with calf thymus DNA by intercalation.     

Interaction studies of DNA binding of ruthenium(II) mixed-ligand complexes: [Ru(phen)2(dtmi)]2+ and [Ru(phen)2(dtni)]2+

Two new ligands, 3-(pyrazin-2-yl)-as-triazino[5,6-f]-5-methoxylisatin (dtmi), 3-(pyrazin-2-yl)-as-triazino[5,6-f]-5-nitroisatin (dtni) and their ruthenium(II) complexes [Ru(phen)2(dtmi)](ClO4)2 (1) and [Ru(phen)2(dtni)](ClO4)2 (2) have been prepared and characterized by elemental analysis, FAB-MS, ES-MS and 1H NMR. The DNA-binding behaviors of complexes have been studied by spectroscopic titration, viscosity measurements, thermal denaturation and circular dichromism (CD). The results indicate that the complexes 1 and 2 interact with calf thymus DNA (CT-DNA) by intercalative mode. The DNA-binding affinity of the complexes 2 is larger than that complex 1 does.