(6Z,9Z,12Z)-6,9,12-Octadecatriene and (3Z,6Z,9Z,12Z)-3,6,9,12-icosatetraene, the novel sex pheromones produced by emerald moths

(6Z,9Z,12Z)-6,9,12-Octadecatriene and (3Z,6Z,9Z,12Z)-3,6,9,12-icosatetraene, hydrocarbons unsaturated more highly than usual lepidopteran Type II pheromones, were identified from geometrid females of Hemithea tritonaria and Thalassodes immissaria intaminata, respectively. The triene was synthesized by a double Wittig reaction between hexanal and an ylide derived from (Z)-1,6-diiodo-3-hexene, and the tetraene was synthesized by a coupling between (Z)-3-undecenal and an ylide derived from (3Z,6Z)-1-iodo-3,6-nonadiene. Each synthetic compound attracted males of the corresponding emerald moths in a field.     

Crystalline O,O′-di-sec-butyl and O,O′-diethyl dithiophosphate platinum(II) complexes: Synthesis, C and P CP/MAS NMR, single crystal X-ray diffraction studies and thermal behaviour

Crystalline bis(O,O′-di-sec-butyldithiophosphato)platinum(II) was prepared and studied by means of ¹³C, ³¹P CP/MAS NMR spectroscopy and single-crystal X-ray diffraction. The unit cell of the platinum(II) compound is comprised of one centrosymmetric mononuclear molecule [Pt{S₂P(O-sec-C₄H₉)₂}₂], in which the dithiophosphate groups display structural equivalence in both ³¹P NMR and XRD data. A pair of the dithiophosphate ligands exhibit the same S,S′-bidentate chelating structural function and form two planar four-membered chelate rings, [PtS₂P], in this molecule. The planar configuration of the [PtS₄] chromophore in structure 1 is governed by the dsp²-hybrid state of platinum(II). The structural states of the dithiophosphate groups in two different samples of complex 1 (one crystallised from ethanol and the other one precipitated from an aqueous solution) are all characterised by almost rhombic ³¹P chemical shift tensors. The observed essential dispersion of the ³¹P NMR chemical shift is caused by a coexistence of six optical isomers of molecule 1. The thermal behaviour of this compound was studied by means of simultaneous thermal analysis (a combination of TG and DSC) under an argon atmosphere. The thermal behaviour shows that the mass of 1 is lost in three steps, involving successive thermal decompositions of the organic and inorganic parts of this compound with platinum(II) dithio-meta-phosphate and reduced metallic platinum as the intermediate and the final products, respectively.     

Iron valence in double-perovskite (Ba,Sr,Ca)2FeMoO6: isovalent substitution effect

In the Fe-Mo based B-site ordered double-perovskite, A₂FeMoO_6.0, with iron in the mixed-valence II/III state, the valence value of Fe is not precisely fixed at 2.5 but may be fine-tuned by means of applying chemical pressure at the A-cation site. This is shown through a systematic ⁵⁷Fe Mössbauer spectroscopy study using a series of A₂FeMoO_6.0 [A=(Ba,Sr) or (Sr,Ca)] samples with high degree of Fe/Mo order, the same stoichiometric oxygen content and also almost the same grain size. The isomer shift values and other hyperfine parameters obtained from the Mössbauer spectra confirm that Fe remains in the mixed-valence state within the whole range of A constituents. However, upon increasing the average cation size at the A site the precise valence of Fe is found to decrease such that within the A=(Ba,Sr) regime the valence of Fe is closer to II, while within the A=(Sr,Ca) regime it is closer to the actual mixed-valence II/III state. As the valence of Fe approaches II, the difference in charges between Fe and Mo increases, and parallel with this the degree of Fe/Mo order increases. Additionally, for the less-ordered samples an increased tendency of clustering of the antisite Fe atoms is deduced from the Mössbauer data.     

Hydrodehalogenation of halogenated pyridines and quinolines by sodium borohydride/N,N,N′,N′-tetramethylethylenediamine under palladium catalysis

A protocol for the hydrodehalogenation of halogenated pyridines and quinolines by the sodium borohydride/N,N,N′,N′-tetramethylethylenediamine (NaBH₄-TMEDA) system under palladium catalysts is reported. Catalytic amounts of [1,1′-bis(diphenylphosphino)ferrocene] dichloropalladium(II) in combination with NaBH₄-TMEDA rapidly hydrodehalogenate chloro(bromo)-pyridines and -quinolines at room temperature in quantitative yields. Chemoselective reduction of 4,7-dichloroquinoline affords 7-chloroquinoline as the sole product in almost quantitative yield. Moreover, palladium(II) acetate-triphenylphosphine and NaBH₄-TMEDA are able to reduce efficiently reactive bromo-pyridines and -quinolines.     

Synthesis and properties of titanomagnetite (Fe3−xTixO4) nanoparticles: A tunable solid-state Fe(II/III) redox system

Titanomagnetite (Fe_3−xTi_xO₄) nanoparticles were synthesized by room temperature aqueous precipitation, in which Ti(IV) replaces Fe(III) and is charge compensated by conversion of Fe(III) to Fe(II) in the unit cell. A comprehensive suite of tools was used to probe composition, structure, and magnetic properties down to site-occupancy level, emphasizing distribution and accessibility of Fe(II) as a function of x. Synthesis of nanoparticles in the range 0 ? x ? 0.6 was attempted; Ti, total Fe and Fe(II) content were verified by chemical analysis. TEM indicated homogeneous spherical 9-12 nm particles. μ-XRD and Mössbauer spectroscopy on anoxic aqueous suspensions verified the inverse spinel structure and Ti(IV) incorporation in the unit cell up to x ? 0.38, based on Fe(II)/Fe(III) ratio deduced from the unit cell edge and Mössbauer spectra. Nanoparticles with a higher value of x possessed a minor amorphous secondary Fe(II)/Ti(IV) phase. XANES/EXAFS indicated Ti(IV) incorporation in the octahedral sublattice (B-site) and proportional increases in Fe(II)/Fe(III) ratio. XA/XMCD indicated that increases arise from increasing B-site Fe(II), and that these charge-balancing equivalents segregate to those B-sites near particle surfaces. Dissolution studies showed that this segregation persists after release of Fe(II) into solution, in amounts systematically proportional to x and thus the Fe(II)/Fe(III) ratio. A mechanistic reaction model was developed entailing mobile B-site Fe(II) supplying a highly interactive surface phase that undergoes interfacial electron transfer with oxidants in solution, sustained by outward Fe(II) migration from particle interiors and concurrent inward migration of charge-balancing cationic vacancies in a ratio of 3:1.     

Studies on the effects of doping cesium metal(III) halides of the type Cs3MIII2X9 (MIII = Sb or Bi, X = Cl or Br)

A series of compounds, Cs₃M^III₂X₉ (M^III = Sb and Bi, X = Cl or Br) are doped with impurity ions (Ba²⁺, Ca²⁺, Sn²⁺, Pb²⁺, Mg²⁺, Fe²⁺, Tl³⁺, In³⁺, Se⁴⁺). Lattices doped with Sn(II), Pb(II) and Se(IV) are colored. Sn-119m Mössbauer data are consistent with the donation of Sn-5s electron density from tin(II) to a conduction band to give a pseudo-tin(IV) electronic environment.     

Synthesis, characterization, crystal structure and antimicrobial activities of new transN,N-substituted macrocyclic dioxocyclam and their copper(II) and nickel(II) complexes

New trans-disubstituted macrocyclic ligands, 1,8-[N,N-bis(3-formyl-12-hydroxy-5-methyl)benzyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L¹), 1,8-[N,N-bis(3-formyl-12-hydroxy-5-bromo)benzyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L²), N,N-bis[1,8-dibenzoyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L³), N,N-bis[1,8-(2-nitrobenzoyl)]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L⁴), and N,N-bis[1,8-(4-nitrobenzoyl)]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L⁵) were synthesized. The ligands were characterized by elemental analysis, FT IR, ¹H NMR and mass spectrometry studies. The crystal structure of L¹ is also reported. The copper(II) and nickel(II) complexes of these ligands were prepared and characterized by elemental analysis, FT IR, UV-Vis and mass spectral studies. The cyclic voltammogram of the complexes of ligand L^1-3 show one-electron quasi-reversible reduction wave in the region −0.65 to −1.13 V, whereas that of L⁴ and L⁵ show two quasi-reversible reduction peaks. Nickel(II) complexes show one electron quasi-reversible oxidation wave at a positive potential in the range +0.95 to +1.06 V. The ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry with nuclear hyperfine spin 3/2. All copper(II) complexes show a normal room temperature magnetic moment value μ_eff 1.70-1.73 BM which is close to the spin only value of 1.73 BM. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts and hydrolysis of 4-nitrophenylphosphate using the copper(II) and nickel(II) complexes as catalysts were carried out. The ligands and their complexes were also screened for antimicrobial activity against Gram-positive, Gram-negative bacteria and human pathogenic fungi.     

The structures of 5-methyl-5-phenyl-5H-dibenzo[b,f] silepin and its saturated analog

The structures of 5-methyl-5-phenyl-5H-dibenzo[b,f] silepin (I) and 5-methyl- 5-phenyl-1O,11-dihydro-5H-dibenzo [b,f] silepin (II) have been determined from three-dimensional X-ray data collected by counter methods. I crystallizes in the orthorhombic space group Pnam with a 7.596(3), b 18.102(5) and c 12.190(2) Å; observed and calculated densities (Z = 4) are 1.17 and 1.18 g cm^?3, respectively. II crystallizes in the monoclinic space group $\text{P}\text{2}{}_1\text{c}$ with a 11.115(3), b 7.920(3), c 20.765(5) Å and β 111.71(2)°; observed and calculated densities (Z = 4) are 1.17 g cm^?3. Anisotropic refinement of nonhydrogen atoms, with hydrogen atoms included at fixed ideal locations, gave conventional R-factors of 4.5% (I) and 5.0% (II). Compound I exhibits the boat conformation for the tricyclic framework and is located on a crystallographically required mirror plane. Com- pound II has the expected folded boat conformation. The torsion angle about the 10,11-bond is 0.0° for I, a crystallographic symmetry requirement, and 89.9° for II. Mean SiC bond distances are 1.863 Å(I) and 1.875 Å(II). The dihedral angles between the planar benzo groups are 129.7° (I) and 137.2° (II); introduc- tion of unsaturation at the 10,11-position decreases the dihedral angle in the tri- cyclic system, i.e., the tricyclic system is more bent.     

The crystal chemistry of Bi6TP2O15+x, T=Fe, Ni, Zn: Isomorphism and polymorphism, structural relationship to Bi6TiP2O16

The crystal structures of compounds with nominal compositions Bi₆FeP₂O_15+x (I), Bi₆NiP₂O_15+x (II) and Bi₆ZnP₂O_15+x (III) were determined from single-crystal X-ray diffraction data. They are monoclinic, space group I2, Z=2. The lattice parameters for (I) are a=11.2644(7), b=5.4380(3), c=11.1440(5) Å, β=96.154(4)°; for (II) a=11.259(7), b=5.461(4), c=11.109(7) Å, β=96.65(1)°; for (III) a=19.7271(5), b=5.4376(2), c=16.9730(6) Å, β=131.932(1)°. Least squares refinements on F² converged for (I) to R1=0.0554, wR₂=0.1408; for (II) R₁=0.0647, wR₂=0.1697; for (III) R₁=0.0385, wR₂=0.1023. The crystals are complexly twinned by 2-fold rotation about , by inversion and by mirror reflection. The structures consist of edge-sharing articulations of OBi₄ tetrahedra forming layers in the a-c plane that then continue by edge-sharing parallel to the b-axis. The three-dimensional networks are bridged by Fe and Ni octahedra in (I) and (II) and by Zn trigonal bipyramids in (III) as well as by oxygen atoms of the PO₄ moieties. Bi also randomly occupies the octahedral sites. Oxygen vacancies exist in the structures of the three compounds due to required charge balances and they occur in the octahedral coordination polyhedron of the transition metal. In compound (III), no positional disorder in atomic sites is present. The Bi-O coordination polyhedra are trigonal prisms with one, two or three faces capped. Magnetic susceptibility data for compound (I) were obtained between 4.2 and 350 K. Between 4.2 and 250 K it is paramagnetic, μ_eff=6.1 μ_B; a magnetic transition occurs above 250 K.     

A concise synthesis of asymmetrical N,N′-disubstituted guanidines

We present a new and concise method for the preparation of asymmetrical N,N′-disubstituted guanidines starting from thiourea via the reaction of N-Boc-protected N′-alkyl/aryl substituted thioureas with an amine in the presence of mercury(II) chloride and triethylamine.     

(N,N-dimethylbenzylamine-2C,N)palladium(II) and -platinium(II) β-diketonates and thio-β-diketonates

(N,N-dimethylbenzylamine-2C,N)palladium(II) and -platinum(II) β-diketonates, DmbaML, have been synthesized by reaction of [DmbaMCl]₂ with the free ligand and KOH, or with the thallium(I) salt of the ligand. The various isomers formed have been investigated by ¹H and ¹⁹F NMR spectroscopy. Infrared and mass spectroscopic studies have also been made on the compounds.     

Complexation studies of Sn(II) by N,N-dimethylformamide and free energy of transfer of Sn(II) from acetonitrile to N,N-dimethylformamide

Studies of the complexation of Sn(II) by N,N-dimethylformamide show that Sn(II) ion forms six successive complexes with the ligand. The stability constants were determined by the method of DeFord and Hume. The free energy of transfer of Sn(II) from acetonitrile to N,N-dimethylformamide and to their mixtures was obtained using the theory of Cox et al. The energy decreases with increasing N,N-dimethylformamide concentration, the decrease being most pronounced for nearly pure acetonitrile.     

Palladium(II) complexes with S-benzyl dithiocarbazate and S-benzyl-N-isopropylidenedithiocarbazate: Synthesis,spectroscopic properties and X-ray crystal structures

Two new palladium(II) bis(NS) chelates, bis(S-benzyl dithiocarbazato)palladium(II) (1) and bis(S-benzyl-N-isopropylidenedithiocarbazato)palladium(II) (2), have been prepared and characterized using single-crystal X-ray diffraction and spectroscopic (electronic, IR and NMR) techniques. Complex 1 has a perfectly square planar trans configuration (point group C_i), while complex 2 has a distorted square planar cis configuration.     

Preconcentration and separation of copper (II) with solvent extraction using N,N′-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane

Preconcentration and separation with solvent extraction of Cu(II) from aqueous solution using N,N′-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane (H₂L) as the new extractant has been studied. Separation of Cu(II) from other metal ions such as Cd(II), Ni(II), Zn(II), Pb(II), Cr(III), Co(II) and Mn(II) at aqueous solutions of various pH values and complexing agent H₂L, has been described. The possible extraction mechanism and the compositions of the extracted species have been determined. The separation factors for these metals using this reagent are reported while efficient methods for the separation of Cu(II) from other metal ions are proposed. From the loaded organic phase, Cu(II) stripping was carried out in one stage with different mineral acid solutions. The stripping efficiency was found to be quantitative in case of HNO₃ and HCl. From quantitative evaluation of the extraction equilibrium data, it has been deduced that the complex extracted is the simple 1:1 chelate, CuL. The extraction constant has a value of logK_ex=−4.05±0.04.     

Die kristall- und molekúlstruktur der dimeren dimethylaluminium- und dimethylgallium-N,N′-dimethylacetamidine [(CH3)2M(NCH3)2CCH3]2 (M = Al,Ga)

Dimethylaluminium- and dimethylgallium-N,N′-dimethylacetamidine (I and II) are doubly associated forming a puckered eight-membered ring. They crystallize isostructurally in the monoclinic space group P2₁/c with two dimers per unit cell. The lattice constants of I are a 8.187, b 7.266, c 14.778 Å, β 103.58° and those of II a 8.163, b 7.277, c 14.835 Å, β 103.46°. The MN and the NC bond lengths within the rings are nearly equal, their mean values are for I: AlN 1.925 Å, CN 1.330 Å and for II: GaN 1.979 Å, CN 1.335 Å. This is also true for the exocyclic bond lengths with average values AlC 1.975 Å, NC 1.474 Å, CC 1.509 Å (for I) and GaC 1.998 Å, NC 1.484 Å and CC 1.507 Å (for II). The metal atoms are tetrahedrally coordinated, and the distortion is only slight. The final R-values are 0.034 and 0.056, respectively.     

Palladium, rhodium and platinum complexes of ortho-xylyl-linked bis-N-heterocyclic carbenes: Synthesis, structure and catalytic activity

New Pd(II), Pt(II) and Rh(I) N-heterocyclic carbene (NHC) complexes containing two NHC units linked by an ortho-xylyl group are described and structurally and spectroscopically characterised. The Pt(II) complexes represent the first examples of Pt-bis(NHC) complexes where the NHC units are linked by an ortho-xylyl group. Functionalisation of the bis(NHC) ligands with heptyl groups has been used as a means of enhancing the solubility of the complexes, in order to facilitate spectroscopic characterisation and catalytic studies. The catalytic activity of the palladium(II) complexes in Heck and Suzuki cross-coupling reactions has been examined to investigate any effects of the diverse structural changes, though these appear to be insignificant.     

Synthesis,spectroscopic and structural investigation of Zn(NCS)2(nicotinamide)2 and [Hg(SCN)2(nicotinamide)]n

Zinc(II) and mercury(II) thiocyanate complexes with nicotinamide, bis(nicotinamide-N)-bis(thiocyanato-N)zinc(II) (1) and catena-[nicotinamide-N-(μ-thiocyanato-S,N)(thiocyanato-S)mercury(II)] (2), have been prepared and characterized by spectroscopic, thermal and X-ray crystallographic methods. The vibrational bands of diagnostic value are compared to the values of the free ligand and the data are in good correlation with the X-ray results. Centrosymmetrical hydrogen bonded dimers are found, R₂²(10) in 1 and R₂²(8) in 2.     

Studies on the aza-Claisen rearrangement of 4,5-dihydroxylated allylic trichloroacetimidates: the stereoselective synthesis of (2R,3S)- and (2S,3S)-2-amino-3,4-dihydroxybutyric acids

Two new synthetic approaches, involving substrate directed aza-Claisen rearrangements and aza-Claisen rearrangements mediated by chiral Pd(II) catalysts, have been developed for the stereoselective synthesis of (2R,3S)-2-amino-3,4-dihydroxybutyric acid, a dihydroxylated α-amino acid from the edible mushroom, Lyophyllum ulmarium and its (2S,3S)-unnatural diastereomer.     

The crystal and molecular structure of acetato(2-phenylazophenyl-C,N′)tellurium(II) and (2-phenylazophenyl-C,N′)thiocyanatotellurium(II)

The crystal and molecular structures of acetato(2-phenylazophenyl-C,N′)tellurium(II) (I) and (2-phenylazophenyl-C,N′)thiocyanatotellurium(II) (II) have been determined. The structure of the former consists of discrete molecules in which weak intramolecular Te?ctdot;O [2.953(4) Å] interactions occur. However, the structure of the latter compound shows a very weak intermolecular Te?ctdot;N [3.535(3) Å] interaction, which links the molecules into dimers. The coordination about tellurium can be considered as approximately trigonal bipyramidal with the carbon atom and the two lone pairs in the equatorial positions and either N and O(I) or N and S (II) in the axial positions.