Water-soluble (η-arene)ruthenium(II)-phosphine complexes and their catalytic activity in the hydrogenation of bicarbonate in aqueous solution

The reactions of [(η⁶-C₆H₆)RuCl₂]₂ and [(η⁶-p-cymene)RuCl₂]₂ with hydrogen in the presence of the water-soluble phosphines tppts (meta-trisulfonated triphenylphosphine) and pta (1,3,5-triaza-7-phosphaadamantane) afforded as the main species [(η⁶-C₆H₆)RuH(tppts)₂]⁺, [(η⁶-C₆H₆)RuH(pta)₂]⁺, [(η⁶-p-cymene)RuH(tppts)₂]⁺ and [(η⁶-p-cymene)RuH(pta)₂]⁺. This latter complex was also formed in the reaction of [(η⁶-p-cymene)RuCl₂(pta)] and hydrogen with a redistribution of pta. In addition, prolonged hydrogenation at elevated temperatures and in the presence of excess of pta led to the formation of the arene-free [RuH(pta)₄Cl], [RuH(pta)₄(H₂O)]⁺, [RuH₂(pta)₄] and [RuH(pta)₅]⁺ complexes. Ru-hydrides, such as [(η⁶-arene)RuH(L)₂]⁺, catalyzed the hydrogenation of bicarbonate to formate in aqueous solutions at p(H₂)=100 bar, T=50-70 °C.     

Reactions of [Ru(H(2)O)(6)](2+) with water-soluble tertiary phosphines

In aqueous solutions under mild conditions, [Ru(H(2)O)(6)](2+) was reacted with various water-soluble tertiary phosphines. As determined by multinuclear NMR spectroscopy, reactions with the sulfonated arylphosphines L =mtppms, ptppms and mtppts yielded only the mono- and bisphosphine complexes, [Ru(H(2)O)(5)L](2+), cis-[Ru(H(2)O)(4)L(2)](2+), and trans-[Ru(H(2)O)(4)L(2)](2+) even in a high ligand excess. With the small aliphatic phosphine L = 1,3,5-triaza-7-phosphatricyclo-[3.3.1.1(3,7)]decane (pta) at [L]:[Ru]= 12:1, the tris- and tetrakisphosphino species, [Ru(H(2)O)(3)(pta)(3)](2+), [Ru(H(2)O)(2)(pta)(4)](2+), [Ru(H(2)O)(OH)(pta)(4)](+), and [Ru(OH)(2)(pta)(4)] were also detected, albeit in minor quantities. These results have significance for the in situ preparation of Ru(II)-tertiary phosphine catalysts. The structures of the complexes trans-[Ru(H(2)O)(4)(ptaMe)(2)](tos)(4)x2H(2)O, trans-[Ru(H(2)O)(4)(ptaH)(2)](tos)(4)[middle dot]2H(2)O, and trans-mer-[RuI(2)(H(2)O)(ptaMe)(3)]I(3)x2H(2)O, containing protonated or methylated pta ligands (ptaH and ptaMe, respectively) were determined by single crystal X-ray diffraction.     

Towards Identification of Essential Structural Elements of Organoruthenium(II)-Pyrithionato Complexes for Anticancer Activity

An organoruthenium(II) complex with pyrithione (2-mercaptopyridine N-oxide) 1 a has previously been identified by our group as a compound with promising anticancer potential without cytotoxicity towards non-cancerous cells. To expand the rather limited research on compounds of this type, an array of novel chlorido and 1,3,5-triaza-7-phosphaadamantane (pta) organoruthenium(II) complexes with methyl-substituted pyrithiones has been prepared. After thorough investigation of the aqueous stability of these complexes, their modes of action have been elucidated at the cellular level. Minor structural alterations in the ruthenium-pyrithionato compounds resulted in fine-tuning of their cytotoxicities. The best performing compounds, 1 b and 2 b , with a chlorido or pta ligand bound to ruthenium, respectively, and a methyl group at the 3-position of the pyrithione scaffold, have been further investigated. Both compounds trigger early apoptosis, induce the generation of reactive oxygen species and G1 arrest in A549 cancer cells, and show no strong interaction with DNA. However, only 1 b also inhibits thioredoxin reductase. Wound healing assays and mitochondrial function evaluation have revealed differences between these two compounds at the cellular level.     

Barium bis(5,5-dimethyl-1,1,1-trifluorohexane-2,4-dionate)(crown-ether) complexes: Synthesis,characterization and crystal structure

The preparation of the barium β-diketonate complexes with crown-ethers [Ba(pta)₂(18-crown-6)] (1), [Ba(pta)₂(18-crown-6)] (THF) (2), [Ba(pta)₂(18-dibenzocrown-6)](C₆H₅CH₃) (3), [Ba(pta)₂(18-dibenzocrown-6)] (4) (pta = 1,1,1-trifluoro-5,5-dimethylhexanedionato-2,4; 18-crown-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane; 18-dibenzocrown-6 = 6,7,9,10,17,18,20,21-octahydrodibenzo[b,k][1,4,7,10,13,16]-hexaoxacyclooctadecane) is described. The complexes 1 and 2 have been synthesized from reaction of metallic barium with 2 molar equiv. of Hpta and 1 molar equiv. of 18-crown-6 in toluene; the complexes 3 and 4 from reaction of Ba(OH)₂·8H₂O with 1 molar equiv. 18-dibenzocrown-6 and 2 molar equiv. Hpta. The complexes were characterized by elemental analyses, IR-spectroscopy, ¹H NMR spectroscopy. The crystal structures of 2 and 3 were determined by means of single-crystal X-ray diffraction methods. A single-crystal X-ray study of 2 and 3 has shown it be monomeric. The coordination number of Barium cation in 2 and 3 is nine owing to nine oxygen atoms from two pta ligands and crown-ether molecule.     

DNA structural distortions induced by ruthenium-arene anticancer compounds

Organometallic ruthenium(II)-arene (RA) compounds combine a rich structural diversity with the potential to overcome existing chemotherapeutic limitations. In particular, the two classes of compounds [Ru(II)(eta(6)-arene)X(en)] and [Ru(II)(eta(6)-arene)(X)2(pta)] (RA-en and RA-pta, respectively; X = leaving group, en = ethylenediamine, pta = 1,3,5-triaza-7-phosphaadamantane) have become the focus of recent anticancer research. In vitro and in vivo studies have shown that they exhibit promising new activity profiles, for which their interactions with DNA are suspected to be a crucial factor. In the present study, we investigate the binding processes of monofunctional RA-en and bifunctional RA-pta to double-stranded DNA and characterize the resulting structural perturbations by means of ab initio and classical molecular dynamics simulations. We find that both RA complexes bind easily through their ruthenium center to the N7 atom of guanine bases. The high flexibility of DNA allows for fast accommodation of the ruthenium complexes into the major groove. Once bound to the host, however, the two complexes induce different DNA structural distortions. Strain induced in the DNA backbone from RA-en complexation is released by a local break of a Watson-Crick base-pair, consistent with the experimentally observed local denaturation. The bulkier RA-pta, on the other hand, bends the DNA helix toward its major groove, resembling the characteristic DNA distortion induced by the classic anticancer drug cisplatin. The atomistic details of the interactions of RA complexes with DNA gained in the present study shed light on some of the anticancer properties of these compounds and should assist future rational compound design.     

Cellular delivery of pyrenyl-arene ruthenium complexes by a water-soluble arene ruthenium metalla-cage

Three pyrenyl-arene ruthenium complexes (M(1)-M(3)) of the general formula [Ru(η(6)-arene-pyrenyl)Cl(2)(pta)] (pta = 1,3,5-triaza-7-phosphaadamantane) have been synthesised and characterised. Prior to the coordination to ruthenium, pyrene was connected to the arene ligand via an alkane chain containing different functional groups: ester (L(1)), ether (L(2)) and amide (L(3)), respectively. Furthermore, the pyrenyl moieties of the M(n) complexes were encapsulated within the hydrophobic cavity of the water soluble metalla-cage, [Ru(6)(η(6)-p-cymene)(6)(tpt)(2)(donq)(3)](6+) (tpt = 2,4,6-tri-(pyridin-4-yl)-1,3,5-triazine; donq = 5,8-dioxydo-1,4-naphthoquinonato), while the arene ruthenium end was pointing out of the cage, thus giving rise to the corresponding host-guest systems [M(n)?Ru(6)(η(6)-p-cymene)(6)(tpt)(2)(donq)(3)](6+) ([M(n)?cage](6+)). The antitumor activity of the pyrenyl-arene ruthenium complexes (M(n)) and the corresponding host-guest systems [M(n)?cage][CF(3)SO(3)](6) were evaluated in vitro in different types of human cancer cell lines (A549, A2780, A2780cisR, Me300 and HeLa). Complex M(2), which contains an ether group within the alkane chain, demonstrated at least a 10 times higher cytotoxicity than the reference compound [Ru(η(6)-p-cymene)Cl(2)(pta)] (RAPTA-C). All host-guest systems [M(n)?cage](6+) showed good anticancer activity with IC(50) values ranging from 2 to 8 μM after 72 h exposure. The fluorescence of the pyrenyl moiety allowed the monitoring of the cellular uptake and revealed an increase of uptake by a factor two of the M(2) complex when encapsulated in the metalla-cage [Ru(6)(η(6)-p-cymene)(6)(tpt)(2)(donq)(3)](6+).     

Structural investigations of copper(II) complexes containing fluorine-substituted β-diketonate ligands

The crystal structures of the β-diketonate complexes Cu(pta)₂, Cu(pta)₂·EtOH, and Cu(F₆-thd)₂ (where pta is the anion of 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dione and F₆-thd is the anion of 2,2-bis(trifluoromethyl)-6,6-dimethylheptane-3,5-dione) were determined. The solid-state structures of Cu(pta)₂ and Cu(F₆-thd)₂ are square planar, while Cu(pta)₂·EtOH is approximately square pyramidal with the EtOH ligand occupying the apical position. In each case, only one geometrical isomer (cis or trans) was observed in the crystals; arguments are presented that both isomers are present in bulk samples. Calculations of molecular volumes for structurally related Cu(II) complexes containing non-fluorinated versus fluorinated ancillary ligands show that fluorine substitution does not significantly affect packing efficiency in the solid-state; however, solvent coordination decreases packing efficiency slightly. [Cu(tdf)(py)(μ-C₃F₇CO₂)]₂ (where tdf is the anion of 1,1,1,2,2,3,3,7,7,8,8,9,9,9-tetradecafluorononane-4,6-dionate), a derived impurity from preparations of Cu(tdf)₂, was isolated in low yield. The copper coordination geometries in the centrosymmetric structure are intermediate between square pyramidal and trigonal bipyramidal, with two unsymmetrically bridging μ,η¹:η¹-C₃F₇CO₂ ligands.     

Effects of Zinc(II) on the Luminescence of Europium(III) in Complexes Containing β‐Diketone and Schiff Bases

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 Zn^II 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 Zn^II had a coordination number of five and was bridged with Eu^III by three donor O‐atoms, i.e., two from the salicylidene moieties and one from the ketonato group pta.     

Study of the incorporation and release of the non-conventional half-sandwich ruthenium(II) metallodrug RAPTA-C on a robust MOF

The highly porous and robust [Ni(8)(OH)(4)(OH(2))(2)(4,4'-(buta-1,3-diyne-1,4-diyl)bispyrazolato)(6)](n) MOF can be used as a proof of concept for the incorporation and release of the non-conventional [Ru(p-cymene)Cl(2)(pta)] RAPTA-C metallodrug.     

Structures and luminescent properties of Sm(III) and Dy(III) coordination polymers with 2,4,6-pyridinetricarboxylic acid

Two rare earth coordination compounds with 2,4,6-pyridinetricarboxylic acid (H₃pta) have been synthesized by the hydrothermal method; the formula is {[RE(pta)(H₂O)₃]?·?H₂O} _n [RE?=?Sm (1) and Dy (2)]. Complexes 1 and 2 are crystallized in the monoclinic crystal system with P2₁/c space group. X-ray structure analyses show the two complexes have the same structure. Each pta^3? connects three rare earth ions. Both the Sm(III) and Dy(III) complexes exhibit characteristic luminescence in the visible region upon excitation with UV-rays.     

Interaction of Sulfonated Ruthenium(II) Polypyridine Complexes with Surfactants Probed by Luminescence Spectroscopy

Novel anionic [RuL₂L′]²⁻ complexes, where L stands for (1,10‐phenanthroline‐4,7‐diyl)bis(benzenesulfonate) (pbbs; 3a ) or (2,2′‐bipyridine)‐4,4′‐disulfonate (bpds; 3b ), and L′ is N‐(1,10‐phenanthrolin‐5‐yl)tetradecanamide (pta; 2a ) or N‐(1,10‐phenanthrolin‐5‐yl)acetamide (paa; 2b ), were synthesized, and their interaction with the prototypical surfactants sodium dodecylsulfate (SDS), cetyl trimethyl ammonium bromide (CTAB), and Triton X‐100 (TX‐100) was investigated by electronic absorption, luminescence spectroscopy, emission‐lifetime determinations, and O₂‐quenching measurements. [Ru(pbbs)₂(pta)]²⁻ ( 5a ) displayed cooperative self‐aggregation in aqueous medium at concentrations above 1.3 μM ; the observed association was enhanced in the presence of either β‐cyclodextrin or NaCl. This amphiphilic Ru^II compound showed the strongest interaction with all the detergents tested: nucleation of surfactant molecules around the luminescent probe was observed below their respective critical micellar concentrations. As much as a 12‐fold increase of the emission intensity and a 3‐fold rise in the lifetime were measured for 5a bound to TX‐100 micelles; the other complexes showed smaller variations. The O₂‐quenching rate constants decreased up to 1/8 of their original value in H₂O (e.g., for [Ru(bpds)₂(pta)]²⁻ ( 6a ) bound to CTAB micelles). Luminescence‐lifetime experiments in H₂O/D₂O allowed the determination of the metal‐complex fraction exposed to solvent after binding to surfactant micelles. For instance, such exposure was as low as 25% for pta complexes⋅CTAB aggregates. The different behaviors observed were rationalized in terms of the Ru^II complex structure, the electrostatic/hydrophobic interactions, and the probe environment.     

Synthesis and characterisation of the water soluble bis-phosphine complex [Ru(η6-cymene)(PPh2(o-C6H4O)-κ2-P,O)(pta)]+ and an investigation of its cytotoxic effects

Metal complexes bearing phosphine ligands are attracting increasing attention for their applications in medicinal chemistry. In particular, organometallic ruthenium-phosphine complexes have been found to exhibit promising antitumour activity. The synthesis, anticancer activity and reactivity of a novel bis-phosphine complex, [Ru(η⁶-cymene)(PPh₂(o-C₆H₄O)-κ²-P,O)(pta)]Cl (pta = 1,3,5-triaza-7-phosphatricyclo[3.3.1.1.]decane), is presented. The complex appears to exhibit its anticancer effect via a different mechanism to other ruthenium-arene pta complexes with labile co-ligands.     

Desulfuration and Cyclization of (Z)‐2‐[Amino(pyridine‐2‐yl)methylene]‐ hydrazonecarbothioamide in the Presence of Manganese(II)

The reaction of (Z)‐2‐[amino(pyridine‐2‐yl)methylene]hydrazonecarbothioamide (HAm4DH) with Mn(ClO₄)₂·6H₂O afforded different mononuclear or polynuclear manganese(II) complexes, the nature of which apparently depended on the solvent used. For example, in ethanol a compound of formula [Mn(HAm4DH)₂](ClO₄)₂ ( 1 ) was obtained, where HAm4DH coordinates as a common tridentate NNS donor, but the [Mn(bpy)₂(NCS)₂] complex ( 2 ) (bpy = 2,2'‐bipyridine) has also been obtained – probably due to C–N bond cleavage of the thiosemicarbazone. Nevertheless, in a basic aqueous medium [Mn(bpy)₃](ClO₄)₂·0.5bpy ( 3 ) is formed and there is structural evidence for chemical transformations of the thiosemicarbazone promoted by Mn^II. Thus, the sulfate in {[Mn(py)₄Mn(py)₂(H₂O)₂(μ‐SO₄)₂]·4H₂O}_n ( 4 ) or sulfate and cyclooctasulfur in [Mn(pta)₂(pdo)]₄(SO₄)₂·4H₂O·S₈] ( 5 ), where pta is 3‐(pyridin‐2‐yl)‐1,2,4‐triazol‐5‐amine and pdo is (2R,4R/2S,4S)‐pentane‐2,4‐diolato, arise from the desulfuration and oxidation of the thiosemicarbazone ligand. The structures of complexes 2 to 5 were established by single‐crystal X‐ray diffraction. The formation of pta is the result of the oxidative cyclization of HAm4DH. In the polynuclear complex 4 , the sulfate acts as an (O,O') bridge between alternating Mn(py)₂(H₂O)₂ and Mn(py)₄ centers. In the tetranuclear complex 5 , pta acts as a bischelating ligand through the N‐pyridine and N‐triazole, and pdo act as a bridge between two manganese atoms. It is also noteworthy that in complexes 4 and 5 hydrogen bonds give rise to different self‐assembly behaviour that leads to complicated supramolecular structures.     

Coordination Frameworks based on 3,5‐Bis(imidazole‐1‐yl)­pyridine and Aromatic Dicarboxylate Ligands: Synthesis,Crystal Structures,and Photoluminescent Properties

Three metal coordination polymers [Zn(bdc)(L)(H₂O)]_n ( 1 ), [Co(pta)(L)(H₂O)₂]_n ( 2 ), and [Cd(tda)(L)(H₂O)]_n ( 3 ) [H₂bdc = 1,2‐benzene dicarboxylate acid, H₂pta = terephthalic acid, H₂tda = 2,5‐thiophenedicarboxylic acid, L = 3,5‐bis(imidazole‐1‐yl)pyridine] were synthesized and structurally characterized by IR spectroscopy, elemental analysis, X‐ray powder diffraction, and X‐ray single crystal diffraction. Complex 1 shows a three‐dimensional (3D) structure with cco topology with the symbol 6⁵ · 8, whereas complex 2 features a 3D structure with cds topology with the symbol 6⁵ · 8. Complex 3 has a 2D network constructed by the cadmium atoms bridged through the ligands tda and L. Their X‐ray powder diffraction patterns were compared with the simulated ones. Moreover, their luminescent properties were investigated in the solid state at room temperature, and the thermogravimetric analyses were carried out to study the thermal stability of the 3D networks.     

Organometallic ruthenium-based antitumor compounds with novel modes of action

Both metal complexes and organic molecules are widely used for the treatment of various diseases including cancer - in addition to surgery and radiotherapy. Recent years have witnessed a surge of interest in the application of organometallic compounds to treat cancer and other diseases. Indeed, the unique properties of organometallic compounds, intermediate between those of classical inorganic and organic materials provide new opportunities in medicinal chemistry. In this review, based on the award lecture at ICBOMC’10, we describe a class of ruthenium(II)-arene complexes that are weakly cytotoxic in vitro, but show selective antimetastatic activity in vivo. These compounds, [Ru(η⁶-p-arene)Cl₂(pta)] termed RAPTA, interact strongly with proteins, with the ability to discriminate binding to different proteins, but show a relatively low propensity to bind DNA, which is considered to be the main target of many metal-based drugs. The basic RAPTA structure is quite stable in physiological environments, and studies have shown that aquation of the chloride bonds occurs, it may not be an essential step for anticancer drug activity - direct substitution with biomolecular targets is also possible. Based on the favorable physicochemical properties of RAPTA compounds, combined with their highly promising pharmacological properties, the structure represents an ideal scaffold for rational drug design. Thus far, strategies to overcome drug resistance, by interference with critical enzymes responsible for drug deactivation, and tumor targeting, by tethering to human serum albumin via hydrolyzable linkers, have been demonstrated. However, many more approaches can be envisaged. In any case, the net result are a type of hybrid compounds, that occupy a niche somewhere between classical cisplatin-type anticancer agents that are widely applied to many tumor types and targeted therapies based on organic structures used to inhibit specific enzymes. As such, should these compounds prove themselves in the clinic it is not inconceivable that they could be rapidly refined to form personalized chemotherapies.     

Thermodynamic study of a series lithium β-diketonates

Thermal behaviour of a series of lithium β-diketonates: Li(dpm) (dpm=dipivaloylmethanate (2,2,6,6-tetramethylheptane-3,5- dionate)), Li(pta) (pta=pivaloyltrifluoracetonate (2,2-dimethyl-6,6,6-trifluoro-3,5-hexanedionate)), Li(tfa) (tfa=trifluoracetylacetonate (1,1,1-trifluoro-2,4-pentandionate)), Li(hfa) (hfa=hexafluoracetylacetonate (1,1,1,5,5,5-hexafluoro-2,4-pentandionate)) has been investigated. Gas phase composition of these complexes has been established. Temperature dependences of vapor pressure of lithium compounds were obtained by static and dynamic methods, and thermodynamic parameters were calculated. Dependence of compound volatility on ligand structure is shown. For Li(dpm) detailed investigation has been done by differential scanning calorimetry (DSC).     

六核钴原子簇化学 3: 一些含Co~6八面体簇骼的原子簇化合物的合成、结构和电化学性质

(R~8P)~4-nCoX~n(R=Ph,Et 等;X=C,B=1,2)与Na~E~x(E=S,Se;X=1,2)在DMF或DMF/乙醇介质中反应得到了一系列六核钴的原子簇化合物Co~6(μ~3-E)~8(PR~3)~6.这些化合物含有正规的或畸变的Co~6八面簇骼.化合物可以用I~2氧化生成正一价的簇合物而不改变簇骼的几何构型,反达来,正一价的簇合物也可以被苊烯钠还生成中性的簇合物.本文还研究了这些化合物的电化学性质并提出了氧化还原反应的电子传递过程.     

Comparison of hydration reactions for "piano-stool" RAPTA-B and [Ru(η6-arene)(en)Cl]+ complexes: density functional theory computational study

The hydration process for two Ru(II) representative half-sandwich complexes: Ru(arene)(pta)Cl(2) (from the RAPTA family) and [Ru(arene)(en)Cl](+) (further labeled as Ru_en) were compared with analogous reaction of cisplatin. In the study, quantum chemical methods were employed. All the complexes were optimized at the B3LYP/6-31G(d) level using Conductor Polarizable Continuum Model (CPCM) solvent continuum model and single-point (SP) energy calculations and determination of electronic properties were performed at the B3LYP∕6-311++G(2df,2pd)/CPCM level. It was found that the hydration model works fairly well for the replacement of the first chloride by water where an acceptable agreement for both Gibbs free energies and rate constants was obtained. However, in the second hydration step worse agreement of the experimental and calculated values was achieved. In agreement with experimental values, the rate constants for the first step can be ordered as RAPTA-B > Ru_en > cisplatin. The rate constants correlate well with binding energies (BEs) of the Pt∕Ru-Cl bond in the reactant complexes. Substitution reactions on Ru_en and cisplatin complexes proceed only via pseudoassociative (associative interchange) mechanism. On the other hand in the case of RAPTA there is also possible a competitive dissociation mechanism with metastable pentacoordinated intermediate. The first hydration step is slightly endothermic for all three complexes by 3-5 kcal∕mol. Estimated BEs confirm that the benzene ligand is relatively weakly bonded assuming the fact that it occupies three coordination positions of the Ru(II) cation.     

由两相体系(C~6H~6/H~2O)合成一些新的二茂锆二芳氧基配合物的研究

本文首次报道用两相法(C~6H~6/H~2O)合成二茂锆二芳氧基配合物,并与绝对无水条件下的合成结果进行了比较,共合成了五个新的配合物, 同时对二氧二茂锆的环戊二烯基钠合成法加以改进,使产率由66%提高到81%.     

Synthesis,Characterization, Electrochemical and Spectroscopic Properties of [Ru(dppt)(bpy)Cl]+ and [Ru(pta)(bpy)Cl]+

Two novel Ru^II complexes [Ru(dppt)(bpy)Cl]ClO₄ (1) and [Ru(pta)(bpy)Cl]ClO₄ (2)[dppt, pta and bpy = 3-(1,10-phenanthrolin-2-yl)-5,6-diphenyl-as-triazine, 3-(1,10-phenanthrolin-2-yl)-as-triazino[5,6-f]acenaphthylene and 2,2-bipyridine, respectively] were synthesized and characterized by elemental analysis and electrospray mass spectrometry, ¹H-n.m.r., and u.v.–vis spectroscopy. The redox properties of the complexes were examined using cyclic voltammetry. Due to the strong -accepting character of asymmetric ligands, the MLCT bands of (1) and (2) are shifted significantly to lower energies by comparison with [Ru(tpy)(bpy)Cl]⁺.