Synthesis and structural characterization of cationic octahedral oxorhenium(V) complexes with bidentate imidazole derivatives

Cationic distorted octahedral complexes [ReOCl(OEt)(L)(PPh₃)]X {L = 2-(1-ethylaminomethyl)-1-methylimidazole (eami), 2-(1-methylaminomethyl)-1-methylimidazole (mami), 2-(1-ethylthiomethyl)-1-methylimidazole (etmi); X=ReO₄, PF₆} were prepared by reaction of trans-[ReOCl₃(PPh₃)₂] with a twofold molar excess of L in ethanol under anaerobic conditions. X-ray structure determinations of [ReOCl(OEt)(eami)(PPh₃)](ReO₄) (1a) and its etmi equivalent (3a) were performed. In 1a coordination of the chloride occurs trans to the imidazole nitrogen. However, in 3a the chloride is coordinated trans to the ethereal sulfur donor of etmi.     

Syntheses and crystal structures of neutral oxorhenium(V) complexes of N2O2-donor tripodal ligands

The neutral distorted octahedral complexes [ReOCl(L)] {H₂L = N,N-bis(2-hydroxybenzyl)-2-(2-aminoethyl)dimethylamine (H₂had); N,N-bis(2-hydroxybenzyl)-aminomethylpyridine (H₂hap); N,N-bis(2-hydroxybenzyl)-2-(2-aminoethyl)pyridine (H₂hae)} were prepared by the reaction of trans-[ReOCl₃(PPh₃)₂] with a twofold molar excess of H₂L in ethanol. X-ray structure determinations of [ReOCl(had)] (1) and [ReOCl(hap)] (2) were performed, and the structures compared. In both complexes the choride is coordinated trans to the tripodal tertiary amino nitrogen, with a phenolate oxygen trans to the oxo oxygen.     

Mono- and di-nuclear oxorhenium(V) complexes of 4,7-diphenyl-1,10-phenanthroline

The reactions of [ReOX₃(AsPh₃)₂] (X = Cl, Br) with 4,7-diphenyl-1,10-phenanthroline (dpphen) have been examined and the complexes [ReO(OMe)X₂(dpphen)] and [Re₂O₃X₄(dpphen)₂]·2/3CH₂Cl₂ (X = Cl, Br) have been obtained. They were characterized by IR, UV–Vis spectroscopy, and single crystal X-ray analysis has been performed for [ReO(OMe)Cl₂(dpphen)] and [Re₂O₃Br₄(dpphen)₂]·2/3CH₂Cl₂. The nature of the frontier orbitals of [ReO(OMe)Cl₂(dpphen)] and [Re₂O₃Br₄(dpphen)₂] and the electronic transitions involved in the absorption spectra have been studied by means of the density functional and time-dependent density functional methods.     

Synthesis,characterization and structure of oxorhenium(V) complexes with 2-methylmercaptobenzamide

The neutral, mononuclear complex [ReO(mta)₂Cl] (1) [Hmta?=?2-(methylmercapto)aniline] was prepared by reaction of trans-[ReOCl₃(PPh₃)₂] with a twofold molar excess of Hmta in methanol. The oxo-bridged dimer (μ-O)[ReO(mta)₂]₂ (2) was synthesized by reacting [ReOCl₃(PPh₃)₂] with a twofold excess of Hmta in a 9?:?1 acetone/water mixture. The compounds were characterized by spectroscopy and complex 1 also by X-ray crystallography. Complex 1 has a distorted octahedral geometry with the chloride coordinated trans to the oxo group, and with the chelating ligands in the equatorial plane in a cis-N cis-S configuration.     

Heteronuclear complexes of oxorhenium(V) with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO2(VI) and their biological activities

Heteronuclear complexes containing oxorhenium(V), with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO₂(VI) ions were prepared by the reaction of the complex ligands [ReO(HL¹)(PPh₃)(OH₂)Cl]Cl (a) and/or [ReO(H₂L²)(PPh₃)(OH₂)Cl]Cl (b), where H₂L¹?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(5,6-diphenyl-1,2,4-triazine-3-ylhydrazone) and H₃L²?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(1H-benzimidazol-2-ylhydrazone), with transition and actinide salts. Heterodinuclear complexes of ReO(V) with Fe(III), Co(II), Ni(II), Cu(II) and Cd(II) were obtained using a 1?:?1 mole ratio of the complex ligand and the metal salt. Heterotrinuclear complexes were obtained containing ReO(V) with UO₂(VI) and Cu(II) using 2?:?1 mole ratios of the complex ligand and the metal salts. The complex ligands a and b coordinate with the heterometal ion via a nitrogen of the heterocyclic ring and the nitrogen atom of the C=N⁷ group. All transition metal cations in the heteronuclear complexes have octahedral configurations, while UO₂(VI)?complexes have distorted dodecahedral geometry. The structures of the complexes were elucidated by IR, ESR, electronic and ¹H NMR spectra, magnetic moments, conductance and TG-DSC measurements. The antifungal activities of the complex ligands and their heteronuclear complexes towards Alternaria alternata and Aspergillus niger showed comparable behavior with some well-known antibiotics.     

Binary and ternary oxorhenium(V) complexes: synthesis,characterization, and crystal structure

A series of anionic five-coordinate binary oxorhenium(V) complexes with dithiolato ligands, Bu₄N[ReO(L¹)₂] (1a), Bu₄N[ReO(L²)₂] (1b), and Bu₄N[ReO(L³)₂] (1c), and a series of neutral octahedral ternary oxorhenium(V) complexes of mixed dithiolato and bipyridine ligands, [ReO(L¹)(bpy)Cl] (2a), [ReO(L²)(bpy)Cl] (2b), and [ReO(L³)(bpy)Cl] (2c) (where L¹H₂ = ethane-1,2-dithiol, L²H₂ = propane-1,3-dithiol, L³H₂ = toluene-3,4-dithiol, and bpy = 2,2′-bipyridine), were isolated and characterized by physicochemical and spectroscopic methods. The solid state structure of 1c was established by X-ray crystallography. All the mononuclear oxorhenium(V) complexes are diamagnetic. The redox behavior of all the complexes has been studied voltammetrically.     

Coordinative, conformational and motional behaviour of triazine-based ligand strands on binding of Pb(II) cations

The coordinative behaviour of two bis(hydrazone)triazine-based ligands in the presence of Pb(II) was investigated. Free ligand, pincer-like and stick-like complexes' X-ray structures are described. The ligands adopt a pyridine-like coordinative behaviour for Pb(II)/ligand molar ratio equal to 1/2 and 1/1, and a pyrimidine-like coordinative behaviour for Pb(II)/ligand molar ratio equal to 2/1. The complexation processes are reversible and may be modulated by external stimuli. They generate conformational and motional behaviour through interconversion of three entities, free ligand, pincer and stick complex.     

Thermal decomposition and mass spectra of mixed ligand copper(II) complexes of 1,10-phenanthroline and coumarin derivatives

Four copper(II) new mix ligand complexes of the coumarin derivative (A¹ = 7-hydroxy-10,11-dihydroindeno[5,4-c]chromen-6(9H)-one, A² = 2-bromo-7-hydroxy-10,11- dihydroindeno[5,4-c]chromen-6(9H)-one, A³ = 7-hydroxy-4-methoxy-10,11-dihydroindeno[5,4-c]chromen-6(9H)-one, and A⁴ = 5-hydroxy-8,9-dihydrobenzo[f]indeno[5,4-c]chromen-4(7H)-one) and 1,10-Phenanthroline have been synthesized. The structural interpretations were confirmed from elemental analyses, magnetic susceptibility and FAB mass spectral, as well as from IR spectral studies. From the analytical, spectroscopic, and thermal data, the stoichiometry of the mentioned complexes was found to be 1:1:1 (coumarin ligand:copper metal:1,10-Phenanthroline). The thermal stabilities of these complexes were studied by thermogravimetric (TG/DTG) and the decomposition steps of these four complexes are investigated. Kinetic parameters such as order of reaction (n) and the energy of activation (E _a) were calculated using Freeman–Carroll method. The pre-exponential factor (A), the activation entropy (S*), the activation enthalpy (H*), and the free energy of activation (G*) were calculated using Horowitz–Matzger equations. Based on the E _a values, the thermal stabilities of complexes in the decreasing order are Cu(II)-2 > Cu(II)-3 > Cu(II)-4 > Cu(II)-1.     

Preparation and reactivity of iridium(III) hydride complexes with pyrazole and imidazole ligands

Pyrazole IrHCl₂(HRpz)P₂ [P = PPh₃, PⁱPr₃; R = H, 3-Me], bis(pyrazole) [IrHCl(HRpz)₂(PPh₃)₂]BPh₄ and imidazole IrHCl₂(HIm)(PPh₃)₂ derivatives were prepared by allowing the IrHCl₂(PPh₃)₃ complex to react with the appropriate azole in refluxing 1,2-dichloroethane. Nitrile IrHCl₂(CH₃CN)(PPh₃)₂ and 2,2′-bipyridine (bpy) [IrHCl(bpy)(PPh₃)₂]BPh₄ derivatives were also prepared using IrHCl₂(PPh₃)₃ as a precursor. The complexes were characterised spectroscopically (IR and NMR) and a geometry in solution was also established. Protonation with Brønsted acid of pyrazole IrHCl₂(Hpz)(PPh₃)₂ and imidazole IrHCl₂(HIm)(PPh₃)₂ complexes proceeded with the loss of the azole ligands and the formation of the unstable IrHCl₂(PPh₃)₂ derivative. Vinyl IrCl₂{CHC(H)R1}(HRpz)P₂ and IrCl₂{CHC(H)R1}(HIm)P₂ (R1 = Ph, p-tolyl, COOCH₃; P = PPh₃, PⁱPr₃) complexes were prepared by allowing hydride-pyrazole IrHCl₂(HRpz)P₂ and hydride-imidazole IrHCl₂(HIm)P₂ to react with an excess of terminal alkyne in 1,2-dichloroethane. The complexes were characterised spectroscopically and by the X-ray crystal structure determination of the IrCl₂{CHC(H)Ph}(Hpz)(PPh₃)₂ derivative.     

Different coordination modes of tetradentate Schiff bases in monomeric and dimeric oxorhenium(V) complexes

The reactions of the tetradentate amine-phenol type Schiff bases H₂sal₂en (1,2-ethylenebis(salicylideneimine) and H₂sal₂mp (1,2-benzylenebis(salicylideneimine)) with trans-[ReOCl₃(PPh₃)₂] or (n-Bu₄N)[ReOCl₄] in air gave the products (µ-O)[ReO(sal₂en)]₂ (1) and [ReOCl(sal₂mp)] (2), respectively. X-ray and spectroscopic studies have shown that 1 contains the linear O=Re–O–Re=O grouping, with the four donor atoms of sal₂en^2? coordinating in the square plane cis to the oxo ions. In 2, a cis oxo-chloro arrangement is observed with a phenolic oxygen being coordinated trans to the oxo group. The terminal Re=O bond lengths in 1 and 2 are 1.709(4) and 1.683(3)?Å, respectively.     

Copper(II) and zinc(II) complexes with terpene derivatives of ethylenediamine: unexpected ligand transformations

Crystallization of copper and zinc complexes with imino terpene derivatives of ethylenediamine causes unexpected chemical transformation of the ligand. Copper(II) chloride catalyzes the hydrolysis of the imine and also acts as a halogenating agent. Crystallization of the zinc complex in acetone is accompanied by the condensation of the ketone with the primary amino group of the ligand.     

Syntheses and structural characterizations of rhenium carbonyl complexes of a bitopic ferrocene-linked bis(pyrazolyl)methane ligand

The reaction between Fe[C₅H₄CH(pz)₂]₂ (pz = pyrazolyl ring) and two equivalents of Re(CO)₅Br in refluxing toluene produces Fe[C₅H₄CH(pz)₂Re(CO)₃Br]₂ (1) in high yield. A similar reaction with a ligand/rhenium ratio of slightly greater than one yields mainly 1 and a low yield of Fe[C₅H₄CH(pz)₂Re(CO)₃Br][C₅H₄CH(pz)₂] (2). The compound H₂C(pz)₂Re(CO)₃Br (3) was prepared by the reaction of H₂C(pz)₂ and Re(CO)₅Br. Compounds 1 and 2 show a reversible oxidation at ca. 0.9 V (Ag/AgCl) that can be assigned to the oxidation of the ferrocene moiety and one irreversible oxidation at ca. 1.4 V assigned to the oxidation of the rhenium metal center. The solid-state structures of 1 · CH₃NO₂, 1 · 2CH₃NO₂, 1 · 2CH₃CN and 2 · 1/2Et₂O · 1/2C₃H₆O have been determined, with 1 · 2CH₃NO₂ and 1 · 2CH₃CN being isomorphous. All four are organized into supramolecular structures by the interactions of the acidic hydrogens of the pyrazolyl and methine groups with either the bromine atoms or carbonyl ligand oxygen atoms, and in 2 the lone pairs on the uncomplexed bis(pyrazolyl)methane units.     

1,10-邻菲咯啉衍生物La(III)配合物的电子结构与抗癌活性

对一系列1,10-邻菲咯啉衍生物La(III)配合物,用密度泛函(DFT)法,在B3LYP/LanL2DZ水平进行理论研究.探讨了配合物的电子结构与其抗癌活性的关系,发现偶极矩(μ)和原子净电荷(Q)都对配合物的抗癌活性有影响,但不起决定性作用,而配合物的LUMO的能量(ELUMO)是决定其抗癌活性强弱的主要因素.并且揭示了配体上侧链烷基链的增长并不是获得高活性分子的最佳途径,而侧链上苯环引入却为设计活性更强的分子提供了可能性.基于理论研究结果,设计了三个具有更高抗癌活性的新配合物.     

Synthesis and photochemistry of binary and mixed ligand complexes of copper(II) containing 5-arylazo-8-hydroxyquinoline derivatives and alkyl xanthates

Summary Mixed ligand complexes of the type K[Cu(x-HQA)Rxan] [x-HQA = 5-arylazo-8-hydroxyquinoline derivatives; Rxan = methyl or ethylxanthate] have been prepared and characterised by elemental analysis, spectral measurements and conductivity. Upon irradiation, solutions of these complexes photoeliminate dinitrogen and a mechanism for this reaction is proposed. The photosensitivity of the oxine ligand was found to be responsible for the observed photolysis of the complexes.     

Syntheses,spectral characterization,thermal properties and DNA cleavage studies of a series of Co(II), Ni(II) and Cu(II) polypyridine complexes with some new imidazole derivatives of 1,10-phenanthroline

In the present study three new imidazole derivatives of phen, 2-(4-hydroxy-3,5-diiodophenyl) imidazo[4,5-f][1,10]phenanthroline L¹, 2-(2-hydroxy-3,5-diiodophenyl)imidazo[4,5-f][1,10]phenanthroline L², 2-(4-hydroxy-5-iodo-3-methoxyphenyl)imidazo[4,5-f][1,10]phenanthroline L³ and their nine new polypyridine complexes[M(N–N)₂(L^1–3)](OAc)₂·(nH₂O) where M is Ni(II), Co(II) and Cu(II) and where (N–N)₂ is 2,2′-bipyridine (bpy)₂ or 1,10-phenanthroline (phen)₂ have been synthesized from the reaction of the metal precursor complexes [M(phen)₂(OAc)₂]·(nH₂O) and [M(bpy)₂(OAc)₂]·(nH₂O) with the respective ligands in ethanol and water. The structures of the compounds were determined with the aid of elemental analysis and FT-IR, UV–Vis, ¹H NMR, ESR spectroscopic methods, magnetic measurements and conductance measurements, further analyzed by powder XRD and thermal studies. Elemental analysis data suggested that the complexes have a 1:2:1 molar ratio among the metal and phen or bpy and L¹/L² or L³ ligands. The spectral data show that all the complexes were six coordinated and possess octahedral geometry around the metal ions. The X-band ESR spectrum of the Cu(II) in DMSO solution at room temperature was recorded and observed anisotropic g values indicate the presence of metal ion in an octahedral environment. The powder XRD patterns of complexes recorded in the range (2θ = 0–80°) and average crystallite size (d_XRD) was calculated using Scherrer’s formula. Thermal decomposition profiles of complexes show high decompound temperatures indicating a good thermal stability. Binding of the complexes with calf thymus DNA (CT DNA) has been investigated by gel electrophoresis. The experimental results indicate that the complexes bind to DNA by intercalation mode and found to promote cleavage of plasmid pBR 322 DNA from the supercoiled form I to the open circular form II upon irradiation.     

Synthesis of mixed-ligand complexes of VO2+ and VO3+ incorporating hydrazone, 1,10-phenanthroline and 8-hydroxyquinoline

2-Aminobenzoylhydrazide (abh) reacts with equimolar amounts of either [V^IVO(acac)₂] or [V^IVO(bzac)₂] (where acac^? and bzac^? are the monoanionic forms of acetylacetone (Hacac) and benzoylacetone (Hbzac), respectively) in the presence of equimolar amounts of 1,10-phenanthroline (phen) to form the octahedral mixed-ligand complexes [V^IVO(L¹)(phen)] (1) and [V^IVO(L²)(phen)] (2), where (L¹)^2? and (L²)^2? are the dianionic forms of the 2-aminobenzoylhydrazone of acetylacetone (H₂L¹) and benzoylacetone (H₂L²). Upon substituting phen by 8-hydroxyquinoline (Hhq), pentavalent [V^VO(L¹)(hq)] (3) and [V^VO(L²)(hq)] (4) complexes were instead obtained. In the crystal structures of 3 and 4, the hydrazone ligands coordinate to the vanadium center through the enolic-O, one imine-N and amide-O in a mer geometry. The amine and the second imine nitrogen form intramolecular hydrogen bonds. Complexes 1 and 2 display quasi-reversible one-electron oxidation peaks near +0.60 V, while the pentavalent 3 and 4 exhibit quasi-reversible one-electron reduction peaks near ?0.18 V versus Ag/AgCl in CH₂Cl₂ solution. EPR spectroscopic studies on 1 and 2 suggest that the unpaired electron is present in the d_xy orbital. DFT studies for 3 indicate that the d_xy orbital of vanadium is the main contributor to the LUMO.     

1H n.m.r. studies of palladium(II) complexes of 2,9-dimethyl-1,10-phenanthroline and 8-hydroxyquinoline

Summary The structures in solution of a series of palladium(II) complexes have been determined by¹H n.m.r. and i.r. spectroscopy. Dicyanobis-(8-hydroxyquinoline)palladium(II) has acis-square-planar configuration, the unidentate 8-hydroxyquinoline molecules bonding to Pd through the nitrogen atoms. Dicyanobis-(2,9-dimethyl-1,10-phenanthroline)-palladium(II) has acis-square planar arrangement about Pd with respect to the nitrogen atoms of the two heterocyclic ligands. The cyanide groups bond to the two apical positions apparently giving rise to a six-coordinate PdlI atom. Dihalo-2,9-dimethyl-1,10-phenanthrolinepalladium(II) (X = Cl, Br, I) exhibits the usualcis-square-planar arrangement of Pd^II, whereas the halobis-(2,9-dimethyl-1,10-phenanthroline) - palladium(II) ion (X = Cl, Br) has a trigonal bipyramidal structure with the halogen atom in the trigonal plane.     

Syntheses, luminescence switching, and electrochemical studies of photochromic dithienyl-1,10-phenanthroline zinc(II) bis(thiolate) complexes

A series of zinc(II) diimine bis(thiolate) complexes with photochromic diarylethene-containing phenanthroline ligands was synthesized, and their photophysical and photochromic properties were studied. The X-ray crystal structures of two of these complexes have been characterized. All complexes exhibit strong 3LLCT phosphorescence at 510-620 nm in the solid state at 77 and 298 K and in EtOH-MeOH glass at 77 K. Detailed studies revealed that the absorption, emission, and electrochemical properties of the complexes could be readily switched via the photochromic ring-closing and ring-opening reactions.     

Syntheses,crystal structures,and catalytic properties of dioxomolybdenum(VI) complexes with hydrazone ligands

Two new dioxomolybdenum(VI) complexes, [MoO₂L¹(CH₃OH)] (1) and [MoO₂L²(H₂O)] (2), where L¹ and L² are dianionic form of N′-(2-hydroxy-3-methoxybenzylidene)-4methoxybenzohydrazide and N′-(2-hydroxy-3methoxybenzylidene)-2-hydroxybenzohydrazide, respectively, have been synthesized and structurally characterized by spectroscopic methods and single-crystal X-ray determination. The complexes are mononuclear molybdenum(VI) compounds. Mo in each complex is octahedral. The difference in the substituent groups in the benzohydrazides leads to coordination of different solvent molecules. Crystals of the complexes are stabilized by hydrogen bonds. The complexes are effective catalysts for sulfoxidation.     

Thio-azo proligands based on 5,6-derivatives-1,10-phenanthroline and their use for iron(II) complexes: Synthesis,characterization and crystal structures

The preparation and characterization of 5,6-substituted-1,10-phenanthrolines, phdtos = 5,6-bistosyl-1,10-phenanthroline (1) and phdbt = 5,6-dibenzyltiol-1,10-phenanthroline (2) are described. The synthesis of (1) was achieved in good yield via the corresponding dihydroxide and 2 was obtained by cross-coupling reaction of 5,6-dibromo-1,10-phenanthroline and benzylthiol mediated by a palladium catalytic system in refluxing toluene (120 °C). These phenanthroline derivatives were used as ligands to afford [Fe^II(phdtos)₃](PF₆)₂ (5) and [Fe^II(phdbt)₃](PF₆)₂ (6) complexes.