Synthesis,crystal, molecular and electronic structures of thiocyanate ruthenium(II) complexes with pyrazole,benzimidazole and triazole ligands

The [Ru(SCN)₂(PPh₃)₂(L)₂] complexes, where L = HPz, PhIm, HTz, have been prepared and studied by IR, NMR, UV–vis spectroscopy and X-ray crystallography. The complexes were prepared in the reactions of [RuCl₂(PPh₃)₃] with pyrazole, benzimidazole and triazole in methanol solutions. The electronic structures of the obtained compounds have been calculated using the TD–DFT method.     

Molecular and spectroscopic properties of chloride and thiocyanate hydridecarbonyl ruthenium(II) complexes with pyridine derivative ligands

[RuH(CO)(dpa)(PPh₃)₂]X and [RuHX(CO)(pyCHPh)(PPh₃)₂] (X = Cl, NCS) complexes (where dpa = 2,2′-dipyridylamine, pyCHPh = 4-(3-phenylpropyl)pyridine) have been prepared and studied using IR, NMR, UV-Vis spectroscopies and X-ray crystallography. The electronic structures and bonding of the obtained complexes were defined on the basis of the DFT method. The electronic spectra of the complexes were calculated and associated with the structure of the molecular orbitals of the complexes. The luminescence properties of the complexes were determined.     

Synthesis, crystal, molecular and electronic structures of ruthenium complexes with a benzoxazole derivative ligand

[RuCl₂(HBO)(PPh₃)₂] and [RuCl(CO)(HBO)(PPh₃)₂] complexes with the 2-(2-hydroxyphenyl)benzoxazole (C₁₃H₉NO₂) ligand were synthesized and characterized by infra red, proton and phosphorus nuclear magnetic resonances, electronic absorption and emission spectroscopies and X-ray crystallography. The experimental studies were completed by theoretical calculations. The calculations show that the donor properties of the carbonyl group predominates the π-acceptor ability in the ruthenium(II) complex. The small transfer of electron density to the acceptor π^∗ carbonyl orbitals is compensated by the presence of the chloride acceptor ligand. The electronic structures of these complexes, presented in particular by density of states diagrams, have been correlated with their ability to fluorescence and have been used to analyze the UV-Vis spectra.     

Synthesis, crystal, molecular and electronic structures of hydride carbonyl ruthenium(II) complexes with pyridine and its derivative ligands

[RuHCl(CO)(PPh₃)₂(py)], [RuHCl(CO)(PPh₃)₂(pyIm)] and [RuCl(CO)(PPh₃)₂(pyoh)]·2CH₃OH complexes (where py = pyridine, pyIm = imidazo[1,2-α]pyridine, pyoh = 2-hydroxy-6-methylpyridine) have been prepared and studied by IR, NMR, UV-Vis spectroscopy and X-ray crystallography. Electronic structures and bonding of the complexes were defined on the basis of DFT method, and the pyridine derivative ligands were compared on the basis of their donor-acceptor properties. Values of the ligand field parameter 10Dq and Racah’s parameters were estimated for the studied compounds, and the luminescence properties were determined.     

Synthesis, spectroscopic and electronic characterizations of two half sandwich ruthenium(II) complexes with 2-(2′-hydroxyphenyl)-benzoxazole and 4-picolinic acid ligands

The [(C₆H₆)RuCl(HPB)] and [(C₆H₆)RuCl₂(C₅H₄NCOOH)] complexes have been prepared and studied by IR, UV-Vis spectroscopy and X-ray crystallography. The complexes was prepared in reaction of [(C₆H₆)RuCl₂]₂ with 2-(2′-hydroxyphenyl)-benzoxazole or 4-picolinic acid in methanol. The electronic spectra of the obtained compounds have been calculated using the TDDFT method. The luminescence property of the half sandwich complex [(C₆H₆)RuCl(HPB)] was studied by the DFT method and the mechanism was suggested.     

Reactivity studies of cyclopentadienyl ruthenium(II), osmium(II) and pentamethylcyclopentadienyl iridium(III) complexes towards 2-(2′-pyridyl)imidazole derivatives

The reaction of [CpRu(PPh₃)₂Cl] and [CpOs(PPh₃)₂Br] with chelating 2-(2′-pyridyl)imidazole (N ∩ N) ligands and NH₄PF₆ yields cationic complexes of the type [CpM(N ∩ N)(PPh₃)]⁺ (1: M = Ru, N ∩ N = 2-(2′-pyridyl)imidazole; 2: M = Ru, N ∩ N = 2-(2′-pyridyl)benzimidazole; 3: M = Ru, N ∩ N = 2-(2′-pyridyl)-4,5-dimethylimidazole; 4: M = Ru, N ∩ N = 2-(2′-pyridyl)-4,5-diphenylimidazole; 5: M = Os, N ∩ N = 2-(2′-pyridyl)imidazole; 6: M = Os, N ∩ N = 2-(2′-pyridyl)benzimidazole). They have been isolated and characterized as their hexafluorophosphate salts. Similarly, in the presence of NH₄PF₆, [Cp∗Ir(μ-Cl)Cl]₂ reacts in dry methanol with N ∩ N chelating ligands to afford in excellent yield [Cp∗Ir(N ∩ N)Cl]PF₆ (7: N ∩ N = 2-(2′-pyridyl)imidazole; 8: N ∩ N = 2-(2′-pyridyl)benzimidazole). All the compounds have been characterized by infrared and NMR spectroscopy and the molecular structure of [1]PF₆, [2]PF₆ and [7]PF₆ by single-crystal X-ray structure analysis.     

The reactions of 8-hydroxyquinoline with [RuHCl(CO)(PPh3)3]: A new ruthenium(II) carbonyl complex with a N-donor ligand

The reaction of [RuHCl(CO)(PPh₃)₃] with 8-hydroxyquinoline has been examined and a novel ruthenium(II) complex – [RuCl(CO)(PPh₃)₂(C₉H₆NO)] – has been obtained. This compound has been studied by IR, UV–Vis (absorption and emission), ¹H and ³¹P NMR spectroscopy, and X-ray crystallography. The molecular orbital diagram of the complex has been calculated with the density functional theory (DFT) method. The spin-allowed singlet–singlet electronic transitions of the complex have been calculated with the time-dependent DFT method, and the UV–Vis spectrum of the compound has been discussed on this basis.     

Spectroscopic,structure, and DFT studies of cationic palladium(II) complexes with imidazole derivative ligands

Two palladium(II) complexes with imidazole derivative ligands have been synthesized. The molecular structures of the complexes were determined by X-ray crystallography and their spectroscopic properties were studied. Based on the crystal structures, computational investigations were carried out to determine the electronic structures of the complexes. The electronic spectra were calculated with use of time-dependent DFT method, and the transitions were correlated with the molecular orbitals of the complexes. The emission of the complex with 1-methylimidazole was examined.     

Synthesis,characterization, crystal structure,and DNA-binding of ruthenium(II) complexes of heterocyclic nitrogen ligands resulting from a benzimidazole-based quinazoline derivative

The reaction of cis-[RuCl₂(dmso)₄] with [6-(2-pyridinyl)-5,6-dihydrobenzimidazo[1,2-c]quinazoline] (L) afforded in pure form a blue ruthenium(II) complex, [Ru(L¹)₂] (1), where the original L changed to [2-(1H-benzoimidazol-2-yl)-phenyl]-pyridin-2-ylmethylene-amine (HL¹ ). Treatment of RuCl₃?·?3H₂O with L in dry tetrahydrofuran in inert atmosphere led to a green ruthenium(II) complex, trans-[RuCl₂(L²)₂] (2), where L was oxidized in situ to the neutral species 6-pyridin-yl-benzo[4,5]imidazo[1,2-c]quinazoline (L² ). Complex 2 was also obtained from the reaction of RuCl₃?·?3H₂O with L² in dry ethanol. Complexes 1 and 2 have been characterized by physico-chemical and spectroscopic tools, and 1 has been structurally characterized by single-crystal X-ray crystallography. The electrochemical behavior of the complexes shows the Ru(III)/Ru(II) couple at different potentials with quasi-reversible voltammograms. The interaction of these complexes with calf thymus DNA by using absorption and emission spectral studies allowed determination of the binding constant K _b and the linear Stern–Volmer quenching constant K _SV.     

Synthesis,spectroscopic characterization,X-ray structure and DFT calculations of copper(II) complex with 2-(2-pyridyl)benzimidazole

The reaction of copper(II) nitrate trihydrate and 2-(2-pyridyl)benzimidazole (pybzim) leads to [Cu(pybzim)₂(NO₃)](NO₃). The compound has been studied by IR, UV–Vis spectroscopy and X-ray crystallography. The electronic structure of the [Cu(pybzim)₂(NO₃)]⁺ cation has been calculated with the density functional theory (DFT) method. The spin-allowed doublet–doublet electronic transitions of [Cu(pybzim)₂(NO₃)]⁺ have been calculated with the time-dependent DFT method, and the UV–Vis spectrum of the title compound has been discussed on this basis.     

Syntheses and crystal structures of binuclear ruthenium complexes bearing 1,8′-bis(diphenylphosphinomethyl)naphthalene

Treatment of [RuCl₂(η⁶-C₆H₆)]_x with bidentate phosphine ligand BDNA [1,8-bis(diphenylphosphinomethyl)naphthalene] in methanol at room temperature gave η⁶-benzene-ruthenium complexes Ru₂Cl₄(η⁶-C₆H₆)₂(μ-BDNA) (1). Complex 1 further reacted with AgBF₄ to form complex [Ru₂Cl₂(μ-Cl)(η⁶-C₆H₆)₂(μ-BDNA)](BF₄) (2). [RuCl₂(η⁶-C₆H₆)]_x reacted with BDNA in refluxing methanol and then the reaction solution was treated with AgBF₄ to generate complex [Ru₂Cl₂(η⁶-C₆H₆)₂(μ-BDNA)₂](BF₄)₂ (3). Their compositions and structures had been determined by elemental analyses, NMR spectra and single crystal X-ray diffractions. X-ray diffraction showed that complex 1 belonged to monoclinic crystal system, P2₁/c space group with Z = 4, a = 12.810 Å, b = 21.507 Å, c = 18.471 Å, β = 107.95°; complex 2 belonged monoclinic crystal system, P2₁/n space group with Z = 4, a = 14.498 Å, b = 15.644 Å, c = 20.788 Å, β = 103.404°, and complex 3 belonged to monoclinic crystal system, P2₁/n space group with Z = 2, a = 13.732 Å, b = 14.351 Å, c = 19.733 Å, β = 94.82°.     

Synthesis,crystal, molecular and electronic structures of thiocyanate ruthenium complexes with pyridine and its derivatives as ligands

The complexes [Ru(SCN)₂(PPh₃)₂(L)₂], where L = py and γ-pic, and [Ru(SCN)₂(PPh₃)₂(L)], where L = py-2-CH₂NH₂ and py-2-CH₂O, have been prepared and studied by IR, NMR, EPR, UV–Vis spectroscopy and X-ray crystallography. The complexes were prepared in the reactions of [RuCl₂(PPh₃)₃] with pyridine, γ-picoline, 2-(aminomethyl)pyridine and 2-(hydroxymethyl)pyridine in methanol solutions. The electronic structures of the obtained compounds have been calculated using the DFT/TD-DFT method.     

A new ruthenium(II) hydride carbonyl complex with pyrimidine ligand

The reaction of [RuHCl(CO)(PPh₃)₃] with pyrimidine gives [RuHCl(CO)(PPh₃)₂(C₄H₄N₂)]. The compound has been studied by IR, UV-Vis and X-ray crystallography. The molecular orbital diagram of the complex has been calculated with density functional theory (DFT). The spin-allowed singlet-singlet electronic transitions of the complex have been calculated with time-dependent DFT method, and the UV-Vis spectrum of the compound has been discussed on this basis. Emission of the compound was studied.     

Tricarbonyl rhenium complexes of bis(pyrazol-1-yl)methane and bis(3,5-dimethylpyrazol-1-yl)methane – Synthesis,spectroscopic characterization,X-ray structure and DFT calculations

Two novel tricarbonyl rhenium complexes based on the bidentate heterocyclic N–N ligands [bis(pyrazol-1-yl)methane(bpzm) and bis(3,5-dimethylpyrazol-1-yl)methane(bdmpzm)] have been synthesized by heating at reflux [Re(CO)₅Cl] with the appropriate N–N ligand in toluene. The compounds have been characterized by IR and UV–Vis spectroscopy and X-ray analysis. Density functional theory (DFT) and time-dependent (TD) DFT calculations have been carried out for the [Re(CO)₃(bdmpzm)Cl] complex.     

Synthesis,spectroscopic and structural characterization of new complex of ruthenium(II) with Hmtpo ligand

The [(PPh₃)₂RuHCl(CO)(Hmtpo)] complex has been prepared and studied by IR, NMR, UV–VIS spectroscopy and X-ray crystallography. The complex was prepared in reactions of [RuHCl(CO)(PPh₃)₃] with 7-hydroxy-5-methyl[1,2,4]triazolo[1,5-a]pyrimidine in methanol. The electronic structure and UV–Vis spectrum of the obtained compound have been calculated using the TD–DFT method.     

Synthesis, characterization and molecular structure of Ru(II) complex with 8-hydroxyquinoline derivative

The new (E)-8-hydroxyquinoline-2-carbaldehyde O-benzyl oxime ligand and its hydride-carbonyl complex of ruthenium was synthesized and characterized by infrared, proton and phosphorus nuclear magnetic resonance, electronic absorption and emission spectroscopy and X-ray crystallography. The experimental studies were complemented by theoretical calculations. From the electronic spectrum of the complex the Racah’s and nepheloauxetic parameters are calculated. The electronic structure of the complexes, presented in particular by the density of states diagram, have been correlated with its ability to fluoresce and used to analyze the UV-Vis spectra.     

Synthesis,characterisation and crystal structures of three trinuclear cadmium(II) complexes with multidentate Schiff base ligands

Three novel Schiff base Cd(II) trimeric complexes, [Cd₃(L¹)₂(SCN)₂(CF₃COO)₂] (1), [Cd₃(L¹)₂(SCN)₂(HCONMe₂)] (2) and [Cd₃(L²)₂{N(CN)₂}₂] (3) have been prepared from two different symmetrical Schiff bases H₂L¹ and H₂L² (where H₂L¹ = N¹,N³-bis(salicylideneimino)diethylenetriamine, a potentially pentadentate Schiff base with a N₃O₂ donor set, and H₂L² = N¹,N³-bis(3-methoxysalicylideneimino)diethylenetriamine, a potentially heptadentate Schiff base with a N₃O₄ donor set). All the complexes have been synthesised under similar synthetic procedures and their crystal structures have been established by single crystal X-ray diffraction methods. The ligands and their metal complexes have been characterised by analytical and spectroscopic techniques. Among the three complexes, 1 and 3 are linear whereas 2 is a cyclic trimer. In 1 and 3, all the doubly phenoxo bridged Cd(II) metal centres are in a distorted octahedral environment. In complex 2, two of the three Cd(II) centres reside in a distorted octahedral environment and the remaining one enjoys a monocapped octahedral geometry. Altogether the variety in the bridging mode of two new salen-type ligands has been established through these complexes.