Three zinc iodide complexes based on phosphane ligands: syntheses,structures, optical properties and TD–DFT calculations

Three zinc iodide complexes based on phosphane ligands, namely diiodidobis(triphenylphosphane‐κP)zinc(II), [ZnI₂(C₁₈H₁₅P₂)₂], ( 1 ), diiodidobis[tris(4‐methylphenyl)phosphane‐κP]zinc(II), [ZnI₂(C₂₁H₂₁P₂)₂], ( 2 ), and [bis(diphenylphosphoryl)methane‐κ²O,O′]zinc(II) tetraiodidozinc(II), [Zn(C₂₅H₂₂O₂P₂)₃][ZnI₄], ( 3 ), have been synthesized and characterized. Single‐crystal X‐ray diffraction revealed that the structures of ( 1 ) and ( 2 ) are both mononuclear four‐coordinated ZnI₂ complexes containing two monodentate phosphane ligands, respectively. Surprisingly, ( 2 ) spontaneously forms an acentric structure, suggesting it might be a potential second‐order NLO material. The crystal structure of complex ( 3 ) is composed of two parts, namely a [Zn(dppmO₂)₃]²⁺ cation [dppmO₂ is bis(diphenylphosphoryl)methane] and a [ZnI₄]²⁻ anion. The UV–Vis absorption spectra, thermal stabilities and photoluminescence spectra of the title complexes have also been studied. Time‐dependent density functional theory (TD–DFT) calculations reveal that the low‐energy UV absorption and the corresponding light emission both result from halide‐ligand charge‐transfer (XLCT) excited states.     

A novel luminescent ionic trinuclear Cu3I2 cluster cuprous complex supported by a P^N ligand: synthesis,structure characterization,properties and TD–DFT calculations

Luminescent cuprous complexes are an important class of coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The title ionic trinuclear Cu₃I₂ complex, tris[μ₂‐diphenyl(pyridin‐2‐yl)phosphane‐κ²P:N]di‐μ₃‐iodido‐tricopper(I)(3 Cu—Cu) hexafluoridophosphate, [Cu₃I₂(C₃₉H₃₂NP)₃]PF₆, conventionally abbreviated as [Cu₃I₂(Ph₂PPy)₃]PF₆, is described. Each Cu^I atom is coordinated by two μ₃‐iodide ligands and by a P and an N atom from two Ph₂PPy ligands, giving rise to a CuI₂PN tetrahedral coordination geometry about each Cu^I centre. The electronic absorption and photoluminescence properties of this trinuclear cluster have been studied on as‐synthesized samples, which had been examined previously by powder X‐ray diffraction. A detailed time‐dependent density functional theory (TD–DFT) study was carried out and showed a green emission derived from a halide‐to‐ligand charge transfer and metal‐to‐ligand charge transfer ³(X+M)LCT excited state.     

A new phosphorescent heteroleptic cuprous complex with a neutral 2‐methylquinolin‐8‐ol ligand: synthesis,structure characterization,properties and TD–DFT calculations

Luminescent Cu^I complexes have emerged as promising substitutes for phosphorescent emitters based on Ir, Pt and Os due to their abundance and low cost. The title heteroleptic cuprous complex, [9,9‐dimethyl‐4,5‐bis(diphenylphosphanyl)‐9H‐xanthene‐κ²P ,P ](2‐methylquinolin‐8‐ol‐κ²N ,O )copper(I) hexafluorophosphate, [Cu(C₁₀H₉NO)(C₃₉H₃₂OP₂)]PF₆, conventionally abbreviated as [Cu(Xantphos)(8‐HOXQ)]PF₆, where Xantphos is the chelating diphosphine ligand 9,9‐dimethyl‐4,5‐bis(diphenylphosphanyl)‐9H‐xanthene and 8‐HOXQ is the N ,O‐chelating ligand 2‐methylquinolin‐8‐ol that remains protonated at the hydroxy O atom, is described. In this complex, the asymmetric unit consists of a hexafluorophosphate anion and a whole mononuclear cation, where the Cu^I atom is coordinated by two P atoms from the Xantphos ligand and by the N and O atoms from the 8‐HOXQ ligand, giving rise to a tetrahedral CuP₂NO coordination geometry. The electronic absorption and photoluminescence properties of this complex have been studied on as‐synthesized samples, whose purity had been determined by powder X‐ray diffraction. In the detailed TD–DFT (time‐dependent density functional theory) studies, the yellow emission appears to be derived from the inter‐ligand charge transfer and metal‐to‐ligand charge transfer (M +L ′)→LCT excited state (LCT is ligand charge transfer).     

Excited state properties,fluorescence energies,and lifetimes of a poly(fluorene‐phenylene), based on TD‐DFT investigation

The structural and electronic properties of fluorene‐phenylene copolymer (FP)_n, n = 1–4 were studied by means of quantum chemical calculations based on density functional theory (DFT) and time dependent density functional theory (TD‐DFT) using B3LYP functional. Geometry optimizations of these oligomers were performed for the ground state and the lowest singlet excited state. It was found that (FP)_n is nonplanar in its ground state while the electronic excitations lead to planarity in its S₁ state. Absorption and fluorescence energies were calculated using TD‐B3LYP/SVP and TD‐B3LYP/SVP+ methods. Vertical excitation energies and fluorescence energies were obtained by extrapolating these values to infinite chain length, resulting in extrapolated values for vertical excitation energy of 2.89 and 2.87 eV, respectively. The S₁ ← S₀ electronic excitation is characterized as a highest occupied molecular orbital to lowest unoccupied molecular orbital transition and is distinguishing in terms of oscillator strength. Fluorescence energies of (FP)_n calculated from TD‐B3LYP/SVP and TD‐B3LYP/SVP+ methods are 2.27 and 2.26 eV, respectively. Radiative lifetimes are predicted to be 0.55 and 0.51 ns for TD‐B3LYP/SVP and TD‐B3LYP/SVP+ calculations, respectively. These fundamental information are valuable data in designing and making of promising materials for LED materials. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Ir(I)–carbonyl complexes of coumarinazoimidazoles: Synthesis structure, electrochemistry, photophysical properties and DFT calculations

The reactions of Vaska’s complex [IrCl(CO)(PPh₃)₂] with 2-(coumaryl-6-azo)imidazole (CZ-H) and its derivatives (CZ-X) have synthesized [Ir(CZ)(CO)(PPh₃)₂] and [Ir(CZ-X)(CO)(PPh₃)₂]. All the complexes have been characterized by FT-IR, UV-Vis, ¹H NMR and FAB-MS spectroscopy. The structural confirmation has been done in one case, by a single crystal X-ray diffraction study, which shows a distorted square pyramidal geometry around the central Ir atom. The complexes are emissive at room temperature. The cyclic voltammetry of the complexes shows a metal centered irreversible oxidation and ligand centered quasireversible reduction couples. To get an insight into the electronic structure, absorption spectra and electrochemical properties, detailed calculations on all three complexes have been performed at the DFT level.     

Theoretical study of two‐dimensionally fused zinc porphyrins: DFT calculations

Electronic structures of D_4h square‐fused zinc porphyrin sheets of two types ( SA , SB ), where SA is a directly meso‐meso‐, β‐β‐, and β‐β‐linked array and SB is a directly β‐fused array, were compared using density functional theory (DFT). The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of oligomeric SA _n are characteristically delocalized at the cyclooctatetraene‐like sites composed of β‐pyrrolic carbons and their nearest‐neighbor nitrogens. Those of oligomeric SB _n remain solitary monomeric features, reflecting weakly interacting porphyrin units. These two‐dimensionally (2D) square‐fused sheets, especially for SA _n, show effective reduction of both the HOMO–LUMO energy gaps (E_g) and the lowest Q‐like excitation energies because of LUMO's greater stabilization with increasing number of porphyrins than the corresponding one‐dimensionally (1D) linear‐fused tapes. To estimate the minimum value of E_g, the electronic band structures of the infinite‐fused SA _∞ and SB _∞ were examined in detail using modern periodic DFT. Results indicate a full metal for SA _∞, with HOMO and LUMO bands crossing the Fermi level, and a semiconductor with E_g ≈ 0.5 eV for SB _∞. Furthermore, the phonon modes and the electron–phonon coupling (EPC) constant of SA _∞ were calculated throughout the Brillouin zone using density functional perturbation theory (DFPT), yielding a weak EPC constant, λ = 0.35. Within the standard phonon‐mediated BCS mechanism, the superconducting transition temperature, T_c is demonstrated using the McMillan formula, predicting ≈0.5 K. Results show that SA _∞ will become a rare synthetic metal/superconductor without a metal‐insulator transition coming from Peierls lattice instability because it has no serious imaginary phonon modes. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

A novel tricarbonyl rhenium complex of 2-benzoylpyridine - Synthesis, spectroscopic characterization, X-ray structure and DFT calculations

The reaction of Re(CO)₅Cl with 2-benzoylpyridine (bopy) has been examined and a novel Re(CO)₃⁺ tricarbonyl - fac-[Re(CO)₃(bopy)Cl] - has been obtained. The compound has been studied by IR, UV-Vis spectroscopy and X-ray crystallography. The molecular orbital diagram of the tricarbonyl has been calculated with the density functional theory (DFT) method. The spin-allowed singlet-singlet electronic transitions of [Re(CO)₃(bopy)Cl] have been calculated with the time-dependent DFT method, and the UV-Vis spectrum of the title compound has been discussed on this basis.     

Intramolecular electronic communication in a dimethylaminoazobenzene–fullerene C60 dyad: An experimental and TD‐DFT study

An electronically push–pull type dimethylaminoazobenzene–fullerene C₆₀ hybrid was designed and synthesized by tailoring N,N‐dimethylaniline as an electron donating auxochrome that intensified charge density on the β‐azonitrogen, and on N‐methylfulleropyrrolidine (NMFP) as an electron acceptor at the 4 and 4′ positions of the azobenzene moiety, respectively. The absorption and charge transfer behavior of the hybrid donor‐bridge‐acceptor dyad were studied experimentally and by performing TD‐DFT calculations. The TD‐DFT predicted charge transfer interactions of the dyad ranging from 747 to 601 nm were experimentally observed in the UV‐vis spectra at 721 nm in toluene and dichloromethane. A 149 mV anodic shift in the first reduction potential of the N?N group of the dyad in comparison with the model aminoazobenzene derivative further supported the phenomenon. Analysis of the charge transfer band through the orbital picture revealed charge displacement from the n_(N?N) (nonbonding) and π _(N?N) type orbitals centered on the donor part to the purely fullerene centered LUMOs and LUMO+n orbitals, delocalized over the entire molecule. The imposed electronic perturbations on the aminoazobenzene moiety upon coupling it with C₆₀ were analyzed by comparing the TD‐DFT predicted and experimentally observed electronic transition energies of the dyad with the model compounds, NMFP and (E)‐N,N‐dimethyl‐4‐(p‐tolyldiazenyl)aniline (AZNME). The n_(N?N) → π*_(N?N) and π_(N?N) → π*_(N?N) transitions of the dyad were bathochromically shifted with a significant charge transfer character. The shifting of π_(N?N) → π*_(N?N) excitation energy closer to the n → π*_(N?N) in comparison with the model aminoazobenzene emphasized the predominant existence of charge separated quinonoid‐like ground state electronic structure. Increasing solvent polarity introduced hyperchromic effect in the π_(N?N) → π*_(N?N) electronic transition at the expense of transitions involved with benzenic states, and the extent of intensity borrowing was quantified adopting the Gaussian deconvolution method. On a comparative scale, the predicted excitation energies were in reasonable agreement with the observed values, demonstrating the efficiency of TD‐DFT in predicting the localized and the charge transfer nature of transitions involved with large electronically asymmetric molecules with HOMO and LUMO centered on different parts of the molecular framework. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Synthesis,structural characterization,density functional theory calculations and biological evaluation of a new organotin(IV) complex containing N‐isonicotinyl‐N',N″‐diaryl phosphorictriamide as N‐donor ligand

A new diorganotin(IV) complex with the formula SnCl₂(CH₃)₂L₂ ( C_1a ), L = 4‐NC₅H₄CONHPO(NCH₃CH₂C₆H₅)₂, was synthesized and characterized using ¹H NMR, ¹³C NMR, ³¹P NMR, ¹¹⁹Sn NMR and infrared spectroscopies. The molecular structure of C_1a was determined using X‐ray crystallography, revealing that C_1a contains hexa‐coordinated Sn(IV) centres with trans‐configuration of donor atoms around them. Each Sn(IV) atom is positioned in the centre of inversion of an octahedron. C_1a forms one‐dimensional chains via two equal intermolecular P?O…H? N hydrogen bonds. These hydrogen bonds produce centrosymmetric rings as a supramolecular hydrogen‐bonded pattern. In order to compare the relative stability of C_1a (with N‐ligated configuration) and its possible O‐ligated isomer, C_1b , density functional theory calculations were performed, the results showing a preference of C_1a over C_1b from an energy point of view. Also, natural bond orbital analysis was carried out to obtain detailed information on the electronic features of the optimized structures. The theoretical results show that intermolecular hydrogen bonding in the crystal structure has a significant role in the stabilization of C_1a , and Sn(IV) interacts more strongly with the N_py atom than the P?O functional group. Furthermore, the free ligand and its complex were tested against three human cancer cell lines, i.e. human cervical carcinoma (HeLa), human prostate cancer (PC‐3) and human breast adenocarcinoma cancer (MCF‐7). C_1a displays moderate to good cytotoxicity towards all three cancer cell lines. Moreover, antibacterial tests were carried out using the disc‐diffusion method, in which C_1a shows high activity against selected Gram‐negative and Gram‐positive bacteria. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis, spectroscopic characterization, X-ray structure and DFT calculations of [ReOCl2(8-Sqn)(OPPh3)]

The reaction of [ReOCl₃(PPh₃)₂] with 8-quinolinethiol (8-HSqn) has been examined, and the [ReOCl₂(8-Sqn)(OPPh₃)] complex has been obtained. It was characterized by IR, UV–Vis spectroscopy and single crystal X-ray analysis. The nature of the frontier orbitals and the electronic transitions involved in the absorption spectrum have been studied by means of the density functional and time-dependent density functional methods.     

Synthesis,spectroscopic characterization,X-ray structure and DFT calculations of rhenium(III) complex with 1-isoquinolinyl phenyl ketone

The [ReCl₃(MeCN)(PPh₃)] complex reacts with 1-isoquinolinyl phenyl ketone (N–O) to give [ReCl₃(N–O)(PPh₃)]. The compound has been studied by IR, UV–Vis spectroscopy, magnetic measurements and X-ray crystallography. The magnetic behavior is characteristic of mononuclear octahedral Re(III) complex with d⁴ low-spin (³T_1g ground state) and arises because of the large spin–orbit coupling, which gives diamagnetic ground state. The molecular orbital diagram of [ReCl₃(N–O)(PPh₃)] has been calculated with the density functional theory (DFT) method, and time-dependent DFT (TD-DFT) calculations have been employed in order to discussion of its spectroscopic properties in more detail.     

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.     

New aqua rhenium oxocomplex; synthesis,characterization, thermal studies,DFT calculations and catalytic oxidations

The aqua rhenium oxocomplex [ReO(OH)(H₂O)₄]^2? (1) has been prepared and characterized by spectroscopy, thermogravimetry, and elemental analysis and its reactivity towards triphenylphosphine has been evaluated. Complex (1) acts as a catalyst precursor in the presence of molecular oxygen for the oxidation of PPh₃ to OPPh₃. This proceeds through complex intermediates like [Re(PPh₃)_n]³⁺ (2), and [ReO(PPh₃)_n]³⁺ (3). The newly prepared complex (1) was also employed as catalyst for catalytic oxidation of cyclohexane. The geometry of [ReO(OH)(H₂O)₄]^2? has also been optimized in the singlet state by the DFT method with B3LYP level of theory.     

Copper(II) complexes of bis(pyrazol-1-yl)methane - Synthesis, spectroscopic characterization, X-ray structure and DFT calculations

Two novel copper(II) complexes incorporating bis(pyrazol-1-yl)methane ligand (bpzm) have been synthesized. The compounds [CuCl(bpzm)₂(H₂O)]Cl·H₂O (1) and [Cu(N₃)₂(bpzm)]_n (2) have been studied by IR, UV-Vis spectroscopy and X-ray crystallography. The experimental studies on the compounds 1 and 2 have been accompanied computationally by the density functional theory (DFT) calculations.     

Synthesis,structure and characterization of two new metal–organic coordination polymers based on the ligand 5‐iodobenzene‐1,3‐dicarboxylate

Two new coordination polymers (CPs) formed from 5‐iodobenzene‐1,3‐dicarboxylic acid (H₂iip) in the presence of the flexible 1,4‐bis(1H‐imidazol‐1‐yl)butane (bimb) auxiliary ligand, namely poly[[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)butane‐κ²N³:N^3′](μ₃‐5‐iodobenzene‐1,3‐dicarboxylato‐κ⁴O¹,O^1′:O³:O^3′)cobalt(II)], [Co(C₈H₃IO₄)(C₁₀H₁₄N₄)]_n or [Co(iip)(bimb)]_n, (1), and poly[[[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)butane‐κ²N³:N^3′](μ₂‐5‐iodobenzene‐1,3‐dicarboxylato‐κ²O¹:O³)zinc(II)] trihydrate], {[Zn(C₈H₃IO₄)(C₁₀H₁₄N₄)]·3H₂O}_n or {[Zn(iip)(bimb)]·3H₂O}_n, (2), were synthesized and characterized by FT–IR spectroscopy, thermogravimetric analysis (TGA), solid‐state UV–Vis spectroscopy, single‐crystal X‐ray diffraction analysis and powder X‐ray diffraction analysis (PXRD). The iip²⁻ ligand in (1) adopts the (κ¹,κ¹‐μ₂)(κ¹, κ¹‐μ₁)‐μ₃ coordination mode, linking adjacent secondary building units into a ladder‐like chain. These chains are further connected by the flexible bimb ligand in a trans–trans–trans conformation. As a result, a twofold three‐dimensional interpenetrating α‐Po network is formed. Complex (2) exhibits a two‐dimensional (4,4) topological network architecture in which the iip²⁻ ligand shows the (κ¹)(κ¹)‐μ₂ coordination mode. The solid‐state UV–Vis spectra of (1) and (2) were investigated, together with the fluorescence properties of (2) in the solid state.     

Synthesis, spectroscopic characterization, X-ray structure and DFT calculations of rhenium(III) complex with bis(3,5-dimethylpyrazol-1-yl)methane

[ReCl₃(MeCN)(PPh₃)₂] reacts with bis(3,5-dimethypyrazol-1-yl)methane (bdmpzm) in acetone to give [ReCl₃(bdmpzm)(PPh₃)]. The compound has been studied by IR, UV–Vis spectroscopy and X-ray crystallography. The molecular orbital diagram of [ReCl₃(bdmpzm)(PPh₃)] has been calculated with the density functional theory (DFT) method.     

Novel Re(I) tricarbonyl complexes of chelating ligands with aromatic N-heterocycle ring and aliphatic amine donor - Synthesis, spectroscopic characterization, X-ray structure and DFT calculations

Three novel tricarbonyl rhenium(I) complexes of chelating ligands with aromatic N-heterocycle ring and aliphatic amine donor (2-aminomethylpyridine (ampy), 2-(2-aminophenyl)-1H-benzimidazole (apbi) and 2-(2-aminophenyl)benzothiazole (apbt)) have been synthesized and characterized. The compounds [Re(CO)₃(ampy)Cl] (1), [Re(CO)₃(apbi)Cl] (2) and [Re(CO)₃(apbt)Cl] (3) have been identified by IR, UV-Vis spectroscopy and X-ray analysis. The experimental studies on the complexes 1, 2 and 3 have been accompanied computationally by the density functional theory (DFT) calculations.     

Synthesis,NMR structural characterization and molecular modeling of substituted thiosemicarbazones and semicarbazones using DFT calculations to prove the syn/anti isomer formation

Thiosemicarbazones possessing electron‐donating and electron‐withdrawing groups were prepared, and their spectral characteristics determined. In all cases, the spectra showed that one isomer was formed, allowing further functionalization to molecules of biological interest. We provide NMR data for some of the thiosemicarbazones and semicarbazones. We also provide evidence that for 2‐pyridyl thiosemicarbazone, the syn isomer slowly converts into the anti isomer in dimethyl sulfoxide solvent with first‐order kinetics. Molecular modeling and density functional theory calculations confirmed these observations. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis,spectroscopic characterization,X-ray structure and DFT calculations of five-coordinated chlorocopper(II) complex with bis(3,5-dimethylpyrazol-1-yl)methane

The reaction of copper dichloride dihydrate and bis(3,5-dimethylpyrazol-1-yl)methane affords [Cu{H₂C(3,5-Me₂pz)₂}₂Cl]Cl · 3H₂O. The compound has been studied by IR, UV–Vis spectroscopy and X-ray crystallography. The electronic structure of the [Cu{H₂C(3,5-Me₂pz)₂}₂Cl]⁺ cation has been calculated with the density functional theory (DFT) method. The spin-allowed doublet–doublet electronic transitions of [Cu{H₂C(3,5-Me₂pz)₂}₂Cl]⁺ have been calculated with the time-dependent DFT method, and the UV–Vis spectrum of the title compound has been discussed on this basis.     

Novel tricarbonyl rhenium complexes of 5,8-quinolinedione derivatives - Synthesis, spectroscopic characterisation, X-ray structure and DFT calculations

The molecular structure of 7-acetamido-2-methyl-quinoline-5,8-dione has been determined and the reactivity of 7-acetamido-2-methyl-quinoline-5,8-dione (1) and 6-acetamido-2-methyl-quinoline-5,8-dione (2) towards Re(CO)₅Cl has been examined. Two novel tricarbonyl rhenium complexes, fac-[Re(CO)₃(7-acetamido-2-methyl-quinoline-5,8-dione)Cl]·CHCl₃ (3·CHCl₃) and fac-[Re(CO)₃(6-acetamido-2-methyl-quinoline-5,8-dione)Cl]₂·CHCl₃ (4·CHCl₃), have been synthesized and characterized spectroscopically and structurally. The electronic spectrum of 3 was investigated at the TDDFT level employing B3LYP functional in combination with LANL2DZ.