Structural and spectral studies of N-2-(pyridyl)-, N-2-(3-, 4-, 5-, and 6-picolyl)- and N-2-(4,6-lutidyl)-N′-2-thiomethoxyphenylthioureas

Structures of the following compounds have been obtained: N-(2-pyridyl)-N′-2-thiomethoxyphenylthiourea, PyTu2SMe, monoclinic, P2₁/c, a=11.905(3), b=4.7660(8), c=23,532(6) Å, β=95.993(8)°, V=1327.9(5) ų and Z=4; N-2-(3-picolyl)-N′-2-thiomethoxyphenyl-thiourea, 3PicTu2SeMe, monoclinic, C2/c, a=22.870(5), b=7.564(1), c=16.941(4) Å, β=98.300(6)°, V=2899.9(9) ų and Z=8; N-2-(4-picolyl)-N′-2-thiomethoxyphenylthiourea, 4PicTu2SMe, monoclinic P2₁/a, a=9.44(5), b=18.18(7), c=8.376(12) Å, β=91.62(5)°, V=1437(1) ų and Z=4; N-2-(5-picolyl)-N′-2-thiomethoxyphenylthiourea, 5PicTu2SMe, monoclinic, C2/c, a=21.807(2), b=7.5940(9), c=17.500(2) Å, β=93.267(6)°, V=2893.3(5) ų and Z=8; N-2-(6-picolyl)-N′-2-thiomethoxyphenylthiourea, 6PicTu2SMe, monoclinic, P2₁/c, a=8.499(4), b=7.819(2), c=22.291(8) Å, β=90.73(3)°, V=1481.2(9) ų and Z=4 and N-2-(4,6-lutidyl)-N′-2-thiomethoxyphenyl-thiourea, 4,6LutTu2SMe, monoclinic, P2₁/c, a=11.621(1), b=9.324(1), c=14.604(1) Å, β=96.378(4)°, V=1572.4(2) ų and Z=4. Comparisons with other N-2-pyridyl-N′-arylthioureas having substituents in the 2-position of the aryl ring are included.     

Structural, spectral and thermal studies of N-2-(4-picolyl)- and N-2-(6-picolyl)-N′-(2-chlorophenyl)thioureas and N-2-(6-picolyl)-N′-(2-bromophenyl)thiourea

N-2-(4-picolyl)-N′-2-chlorophenylthiourea, 4PicTu2Cl, monoclinic, P2₁/c, a=10.068(5), b=11.715(2), β=96.88(4)°, and Z=4; N-2-(6-picolyl)-N′-2-chlorophenylthiourea, 6PicTu2Cl, triclinic, P-1, a=7.4250(8), b=7.5690(16), c=12.664(3) Å, =105.706(17), β=103.181(13), γ=90.063(13)°, V=665.6(2) ų and Z=2 and N-2-(6-picolyl)-N′-2-bromophenylthiourea, 6PicTu2Br, triclinic, P-1, a=7.512(4), b=7.535(6), c=12.575(4) Å, a=103.14(3), β=105.67(3), γ=90.28(4)°, V=665.7(2) ų and Z=2. The intramolecular hydrogen bonding between N′H and the pyridine nitrogen and intermolecular hydrogen bonding involving the thione sulfur and the NH hydrogen, as well as the planarity of the molecules, are affected by the position of the methyl substituent on the pyridine ring. The enthalpies of fusion and melting points of these thioureas are also affected. ¹H NMR studies in CDCl₃ show the NH′ hydrogen resonance considerably downfield from other resonances in their spectra.     

Conformational and structural analysis of N-N′-bis(4-methoxybenzylidene)ethylenediamine

The Schiff base compound, N-N′-bis(4-methoxybenzylidene)ethylenediamine (C₁₈H₂₀N₂O₂) has been synthesized and its crystal structure has been investigated by X-ray analysis and PM3 method. The compound crystallizes in monoclinic space group P2₁/n with a=10.190(1), b=7.954(1), c=10.636(1) Å, β=111.68(1)°, V=801.1(1) ų, Z=2 and D_cal=1.229 Mgm⁻³. The title structure was solved by direct methods and refined to R=0.056 for 2414 reflections [I>3.0σ(I)] by full-matrix anisotropic least-squares methods. The energy profile of the compound was calculated by PM3 method as a function of θ[N1′–C9′–C9–N1]. The most stable molecular structure of the title compound is the anti conformation, which is different in energy by 5.0 and 1.0 kcal mol⁻¹ from the eclipsed conformation I and gauche conformations, (III and V), respectively.     

Syntheses of mixed ligands complexes of Ru(II) with 4,4′-dicarboxy-2,2′-bipyridine and substituted pteridinedione and the use of these complexes in electrochemical photovoltaic cells

The synthesis, spectral and photoelectrochemical studies of mixed ligand complexes of [Ru(dcbpy)₂(LL)]Cl₂, where LL=2,4-(1,3-N,N′-dimethyl)pteridinedione (DMP), 6,7-dimethyl-2,4-(1,3-N,N′-dimethyl)pteridinedione (MDMP), 6,7-diphenyl-2,4-(1,3-N,N′-dimethyl)pteridinedione (PhDMP), dibenzo[h,j]-(1,3-N,N′-dimethyl)isoalloxazine (BIAlo), 6,7-bis(pyrid-2-yl)-2,4-(1,3-N,N′-dimethyl) pteridinedione (PyDMP) were carried out. These complexes were attached to sol–gel processed TiO₂ electrodes and the photocells fabricated were illuminated with polychromatic radiation in the presence of I₂/I₃⁻ as redox electrolyte. The incident photon to current conversion efficiency determined was found to be 20–48%.     

Ethylene oligomerization by diimine iron(II) complexes/EAO

The catalytic properties of a series of Fe(II) diimine complexes (diimine=N,N′-o-phenylenebis(salicylideneaminato), N,N′-ethylenebis(salicylideneaminato), N,N′-o-phenylenebisbenzal, N,N′-ethylenebisbenzal) in combination with ethylaluminoxane (EAO) for ethylene oligomerization have been investigated. Treatment of the iron(II) complexes with EAO in toluene generates active catalytic systems in situ that oligomerize ethylene to low-carbon olefins. The effects of reaction temperature, ratios of Al/Fe and reaction periods on catalytic activity and product distribution have been studied. The activity of complex FeCl₂(PhCH=o-NC₆H₄N=CHPh) with EAO at 200°C is 1.35×10⁵ g oligomers/mol Fe·h, and the selectivity of C_4–10 olefins is 84.8%.     

Molecular structure and electrochemical properties of the Pt complex of 1,1′-bis(methylthio)ferrocene and the Pd complexes of 1,4,7-trithia[7]- and 1,5,9-trithia[9] (1,1′)ferrocenophanes

Molecular structures of (triphenylphosphine) [1,1′-bis-(methylthio)ferrocene-S,S′,Fe]Pt(BF₄)₂ (1), (1,5,9-trithia[9]ferrocenophane-S,S′,S″,Fe)Pd(BF₄)₂ (2), and (acetonitrile)(1,4,7-trithia[7]ferrocenophane-S,S′,S″,Fe)Pd(BF₄)₂ (3) were determined by X-ray analyses. The Pt in 1 and the Pd atom in 2 have a somewhat distorted square-planar geometry including the Fe atom of the ferrocene moiety, while the Pd atom in 3 is coordinated by one equivalent of acetonitrile and takes a distorted tetragonal-pyramidal geometry. The distances of the Fe---M bond (M = Pd, Pt) in 1–3 are 2.851(2), 2.827(2), and 3.0962(8) Å, respectively. Cyclic voltammetry of 1–3 gave no reversible wave, but afforded some information supporting the presence of a dative bond.     

Structural and spectral studies on N-(4-chloro)benzoyl-N′-(4-tolyl)thiourea

The crystal and molecular structure of the N-(4-chloro)benzoyl-N′-(4-tolyl)thiourea (C₁₅H₁₃N₂OSCl, M_r=304.79) is determined by X-ray diffraction. The crystal structure is monoclinic, space group: P2₁/n, a=16.097(6), b=4.5989(2), c=19.388(7) Å and β=89.299(6)° V=1434.7(9)ų, Z=4. FTIR and NMR spectra have been characterized. The interactions of intramolecular and intermolecular hydrogen bonds have been discussed. Density functional theory (DFT) (B3LYP) methods have been used to determine the structure and energies of stable conformers. Minimum energy conformations are calculated as a function of the torsion angle θ (C13–N1–C14–N2) varied every 30°. The optimized geometry corresponding to crystal structure is the most stable conformation. This has partly been attributed to intramolecular hydrogen bonds. With the basis sets of the 6-311G* quality, the DFT calculated bond parameters and harmonic vibrations are predicted in a very good agreement with experimental data.     

Hf, Ta, W and Re experimental L X-ray fluorescence cross-sections at 12, 13 and 14 keV with synchrotron radiation

Experimental determinations of L X-ray fluorescence cross-sections for elements with 72≤Z≤75 at 12, 13 and 14 keV were carried out with synchrotron radiation. The experimental set-up provided a linearly polarized monoenergetic photon beam producing a very low background, which improved the signal-to-noise ratio and reduced the experimental uncertainties. Results of the experimental cross-sections obtained for the L lines were grouped considering the transitions scheme, the energies of the emission lines and the detector's resolution. The data obtained were compared with theoretical ones using two different data tables. A very good agreement was found between our experimental values and the theoretical values calculated using Puri's data (X-Ray Spectrom. 22 (1993) 358–361).     

Molecular and crystal structures of N,N′-propylene- and N,N′-phenylene-diylbis [3-(1-aminoethyl)-6-methyl-2H-pyran-2,4(3H)-dione]

Two macrocyclic ligands, N,N′-propylene-diylbis[3-(1-aminoethyl)-6-methyl-2H-pyran-2,4(3H)-dione] I and N,N′-phenylene-diylbis[3-(1-aminoethyl)-6-methyl-2H-pyran-2,4(3H)-dione] II, have been prepared by the condensation of dehydroacetic acid (3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one) with 1,2-phenylenediamine and 1,3-propylenediamine. They have been characterized by means of elemental analysis, IR spectroscopy as well as by X-ray crystallography. The molecular structures of the compounds I and II can be described as consisting of two β-enaminone-2-pyrone rings interlaced with either alkyl chain in I or phenyl ring in II. The X-ray studies confirmed the existence of strong N–HO intramolecular hydrogen bonds in both structures. Their lengths are in accordance to lengths of RAHB intramolecular hydrogen bonds in 1,3-diketones, aryl-hydrazones, β-enaminones and related heterodienes (2.5–2.6 Å) [P. Gilli, V. Bertolasi, V. Ferretti and G. Gilli, J. Am. Chem. Soc., 122 (2000) 10405].     

Potential of ethylenediaminedi(o-hydroxyphenylacetic acid) and N,N'-bis(hydroxybenzyl)ethylenediamine-N,N'-diacetic acid for the determination of metal ions by capillary electrophoresis

Two aromatic polyaminocarboxylate ligands, ethylenediaminedi(o-hydroxyphenylacetic acid) (EDDHA) and N,N′-bis(hydroxybenzyl)ethylenediamine-N,N′-diacetic acid (HBED), were applied for the separation of transition and heavy metal ions by the ion-exchange variant of electrokinetic chromatography. EDDHA structure contains two chiral carbon centers. It makes it impossible to use the commercially available ligand. All the studied metal ions showed two peaks, which correspond to meso and rac forms of the ligand. The separation of metal–HBED chelates was performed using poly(diallyldimethylammonium) polycations in mixed acetate–hydroxide form. Simultaneous separation of nine single- and nine double-charged HBED chelates, including In(III), Ga(III), Co(II)–(III) and Mn(II)–(III) pairs demonstrated the efficiency of 40 000–400 000 theoretical plates. The separation of Co(III), Fe(III) complexes with different arrangements of donor groups and oxidation of Co(II), Mn(II), Fe(II) ions in reaction with HBED have been discussed.     

Coordination geometry of chromium(VI) species. The first example of cis-bridging chromate ions in helically structured catena(μ-CrO4-O,O′)[Ni(HIm)3H2O]

Nickel(II) chromate complex with imidazole (HIm) was isolated from the [Ni²⁺–HIm–CrO₄²⁻] system in various experimental conditions, i.e. reagent molar ratios and nickel(II) salts. The catena(μ-CrO₄-O,O′)[Ni(HIm)₃H₂O] (1) crystallizes in monoclinic crystal system—space group P2₁/n with cell parameters: a=11.784(2), b=8.899(2), c=13.934(3) (Å), β=95.19(3) (°). The unit cell contains two independent helixes, left- and right-handed, stabilized by intrahelical and interhelical hydrogen bonds (HB) and π–π interactions. The cis coordination of the CrO₄²⁻ anions and the HB systems appeared to be the main determinants of the helical architecture. To the best of our knowledge the cis-chromate coordination was observed for the first time. The cis coordination causes the distortion of the nickel octahedron, which was analysed by 4 K single crystal electronic spectra with D_4h symmetry approximation (gaussian resolution and crystal field parameters). This symmetry was also confirmed with the polarised electronic spectra. The magnetic properties of the complex suggest the occurrence of weak intrachain antiferromagnetic interactions between the magnetic Ni^II center. The computational DFT studies of complex 1 assuming three possible isomers mer[(HIm)₃]–cis[(CrO₄²⁻)₂], mer–trans and fac–cis suggested that the main contribution to the stability of 1 might have interhelical and intrahelical hydrogen bonds.     

Measurement of atomic L shell fluorescence (ω1, ω2, ω3) and Auger (a1, a2 and a3) yields for some elements in the atomic number range 59≤Z≤85

A comprehensive set of theoretical Coster–Kronig and fluorescence yields are presented for atomic numbers 18≤Z≤100. These quantities are based on ab initio relativistic calculations. Agreement with experimental values is fair for ω₁ and generally good for ω₂, ω₃ (Z≥54) [1]. Therefore, atomic L shell fluorescence (ω₁, ω₂, ω₃) and Auger yields (a₁, a₂ and a₃) for some elements in the atomic number range 59≤Z≤85 were determined. These selected measured semi-empirical values were also fitted by least squares to polynomials in the Z of the form ∑_na_nZⁿ and compared with theoretical and with earlier fitted values.     

3-exo,3′-exo-(1R,1′R)-Bithiocamphor — a versatile source for functionally different 3,3′-bibornane derivatives, II. 1 An access to 3-exo,3′-exo-(1r,1′r)-bicamphor and related compounds

3-exo,3′-exo-(1R,1′R)-bicamphor (12) is obtained from 3-exo,3′-exo-(1R,1′R)-bithtiocamphor (3) by condensation with hydrazine hydrate followed by hydrolysis of the resulting dihydropyridazine 11. Deprotonation of 12 with NaH and subsequent treatment with potassium hexacyanoferrate (III) furnishes the 2,2′-dioxo-3,3′-bibornanylidene 13, whilst reduction of 12 with L1AlH₄ affords the 3,3′-biisoborneol 16. Further related transformations to various 2,2′-difunctional 3,3′-bibornane derivatives are described, which are could be of interest as chiral ligands     

Synthesis and crystal structure of a complex bearing interesting structural motifs: [Cu (C4H7N3) H2O (4,4′-Hbpy)]·SO4·NO3

A new complex [Cu (C₄H₇N₃) H₂O (4,4′-Hbpy)]·SO₄·NO₃ was synthesized and X-ray characterized. Elemental analysis, X-ray diffraction and infrared spectroscopy of the complex were performed. The crystal system is orthorhombic. Crystal data: Fw=498.98, spacegroup: P212121. Z=4, a=14.952(3), b=20.491(4), c=6.713 Å. V=2056.7(9) Å. λ(Mo-K)=0.71070 Å. μ=12.18 cm⁻¹, D_calc=1.66 g/cm³, F₀₀₀=1032.00, R=0.062, Rw=0.087. X-ray analysis illustrated that 4,4′-bpy is mono-protonated and that there are two kinds of anions in one molecule, which give rise to the hydrogen interaction between the molecules in the crystal. Then an extended three-dimensional network is formed along the hydrogen bonds and π–π bonds between the pyridine rings.     

Quantal state-to-state H-atom exchange cross sections of low energy 1H (v= 0) + Br reactions

The dynamics of the IH + Br heavy-light + heavy system is treated using the Born-Oppenheimer-type separation between the light and the heavy nuclear motions. The hydrogenic wavefunctions, that describe the H-nucleus motion for clamped I and Br nuclei, provide the potential energy curves and couplings that govern the I-Br relative motion. The Hatom exchange cross sections in the reactive collision: IH(v= 0,j) + Br → I + HBr(v′,j′) are found to strongly depend upon j and to be large only for v′ = 1 with j′ = 16–20 and for v′ = 2 with j′ = 8–11. The present results are compared to our previous estimates, to results of classical trajectory calculations and to available experimental data.     

Identification and quantification of 13 components in Angelica sinensis (Danggui) by gas chromatography-mass spectrometry coupled with pressurized liquid extraction

Angelica sinensis (Danggui in Chinese), a well-known traditional Chinese medicine, is also used as a health food product for women's care in Europe and America. Therefore, the demand for Danggui is enormous throughout the world. Due to the shortage of Angelica sinensis, Angelica acutiloba and Angelica gigas are commonly used as the substitutes of Danggui in the market of southeast Asia. However, the three common Angelica roots showed variation in their genetic and chemical composition. Up to date, it is thought that ferulic acid, ligustilide and other phthalides such as butylidenephthalide are the biologically active components of Danggui. In this paper, the contents of 13 compounds including ferulic acid, Z-ligustilide, E-ligustilide, Z-butylidenephthalide, E-butylidenephthalide, 3-butylphthalide, 3-butylidene-4-hydroxyphthalide, senkyunolide A, 6,7-epoxyligustilide, senkyunolide F, senkyunolide H, senkyunolide I, and 6,7-dihydroxyligustilide were determined or estimated by using gas chromatography-mass spectrometry (GC-MS) coupled with pressurized liquid extraction (PLE). The results showed that GC-MS coupled with PLE offered a simple, rapid and high sensitive method to analysis of components in Angelica root. And the contents of investigated compounds in Angelica sinensis, Angelica acutiloba and Angelica gigas, which are used as Danggui in China, Japan and Korea, respectively, were highly variant. It is thought that interaction of multiple chemical compounds contributes to the therapeutic effects of Chinese medicines. However, the overall clinical efficacy of these different Danggui has not been determined. Therefore, comparison of chemical components and pharmacological activities of different Angelica root is helpful to elucidate the mechanism of therapeutic effects of Danggui.     

Formation and structure of [Co{Ph2PN(Bu)PPh2-P,P′}2(CO)][Co)(CO)4] - a cage molecule-pair or an ion-pair complex?

The strong π-acid ligand Ph₂PN(ⁱBu)PPh₂ reacts with Co₂(CO)_S (1:1) to give Co₂[μ-Ph₂PN(ⁱBu)PPh₂] (μ-CO)₂(CO)₄ (1); however, when the ratio is 2:1 a novel species [Co{Ph₂PN(ⁱBu)PPh₂-P,P′}₂(CO)][Co(CO)₄] (2) has been obtained. Crystal data for 2: M_r = 1140.83; triclinic, space group P , a = 12.330(2), b = 13.340(2), c = 18.122(3) Å, = 86.63(1), β = 80.75(1), γ = 84.24(1)°, V = 2924 ų, Z = 2; R = 0.060 for 3711 reflections having I 3σ(I). The results of X-ray diffraction, ESR, variable-temperature magnetic susceptibility, conductivity, and XPS analysis support that the species 2 is a d⁹-d⁹ cage molecule-pair. The mechanism for the formation of the species 2 has been investigated initially by ³¹P NMR.     

Far infrared spectra, conformational equilibria, vibrational assignments, ab initio calculations and structural parameters for 2-bromoethanol

The far infrared spectrum from 370 to 50 cm⁻¹ of gaseous 2-bromoethanol, BrCH₂CH₂OH, was recorded at a resolution of 0.10 cm⁻¹. The fundamental O–H torsion of the more stable gauche (Gg′) conformer, where the capital G refers to internal rotation around the C–C bond and the lower case g to the internal rotation around the C–O bond, was observed as a series of Q-branch transitions beginning at 340 cm⁻¹. The corresponding O–H torsional modes were observed for two of the other high energy conformers, Tg (285 cm⁻¹) and Tt (234 cm⁻¹). The heavy atom asymmetric torsion (rotation around C–C bond) for the Gg′ conformer has been observed at 140 cm⁻¹. Variable temperature (−63 to −100°C) studies of the infrared spectra (4000–400 cm⁻¹) of the sample dissolved in liquid xenon have been recorded. From these data the enthalpy differences have been determined to be 411±40 cm⁻¹ (4.92±0.48 kJ/mol) for the Gg′/Tt and 315±40 cm⁻¹ (3.76±0.48 kJ/mol) for the Gg′/Tg, with the Gg′ conformer the most stable form. Additionally, the infrared spectrum of the gas, and Raman spectrum of the liquid phase are reported. The structural parameters, conformational stabilities, barriers to internal rotation and fundamental frequencies have been obtained from ab initio calculations utilizing different basis sets at the restricted Hartree–Fock or with full electron correlation by the perturbation method to second order. The theoretical results are compared to the experimental results when appropriate. Combining the ab initio calculations with the microwave rotational constants, r₀ adjusted parameters have been obtained for the three 2-haloethanols (F, Cl and Br) for the Gg′ conformers.     

Synthesis, spectroscopic studies and nonlinear optical behavior of N,N′-bis(2-hydroxy-1-naphthylmethylidene)-1-methyl-1,2-diaminoethane-N,N′,O,O′-nickel(II)

A Schiff base complex N,N′-bis(2-hydroxy-1-naphthylmethylidene)-1-methyl-1,2- diaminoethane-N,N′,O,O′-nickel(II) has been synthesized. The title compound has been characterized by FT-IR and UV–vis spectroscopies. The UV–vis experiments indicate that the compound has solvatochromism in the UV region, implying non-zero molecular first hyperpolarizability. To investigate microscopic second-order nonlinear optical (NLO) behavior of the examined complex, the electric dipole moments (μ) and the first static hyperpolarizabilities (β) were computed using Finite Field second-order Møller Plesset (FF MP2) perturbation procedure. According to ab initio quantum mechanical calculations, the title complex exhibits non-zero β values, revealing microscopic second-order NLO behavior.     

Cyano-bridged bimetallic complexes of copper(II) with tetracyanonickelate(II). Crystal structure of [Cu(dpt)Ni(CN)4]

Five new complexes of composition [Cu(dpt)Ni(CN)₄] (1) (dpt=dipropylenetriamine), [Cu(dien)Ni(CN)₄]·2H₂O (2) (dien=diethylenetriamine), [Cu(N,N′-dimeen)Ni(CN)₄]·H₂O (3) (N,N′-dimeen=N,N′-dimethylethylenediamine), [Cu(N,N-dimeen)Ni(CN)₄]·H₂O (4) (N,N-dimeen=N,N-dimethylethylenediamine) and [Cu(trimeen)Ni(CN)₄] (5) (trimeen=N,N,N′-trimethylethylenediamine) have been obtained by the reactions of the mixture of Cu(ClO₄)₂·6H₂O, appropriate amine and K₂[Ni(CN)₄] in water and have been characterized by IR and UV–Vis spectroscopies and magnetic measurements. The crystal structure of [Cu(dpt)Ni(CN)₄] (1) has been determined by single-crystal X-ray analysis. The structure of 1 consists of a one-dimensional polymeric chain ---Cu(dpt)---NC---Ni(CN)₂---CN---Cu(dpt)--- in which the Cu(II) and Ni(II) atoms are linked by CN groups. The nickel atom is four coordinate with four cyanide-carbon atoms (two cyano groups are terminal and two cyano groups (in cis fashion) are bridged) in a square-planar arrangement and the copper atom is five coordinate with two cyanide-nitrogen and three dpt-nitrogen atoms, in a distorted square-pyramidal arrangement. The temperature dependence of magnetic susceptibility (2–300 K) was measured for compound 1. The magnetic investigation showed the presence of a very weak antiferromagnetic interaction (J=−0.16 cm⁻¹) between the copper atoms within each chain through the diamagnetic Ni(CN)₄ ²⁻ ions.