Kinetics and mechanism of the photolytic CO-substitutions of cyclopentadienyl(dicarbonyl)iron thiocarboxylate complexes,Cp′Fe(CO)2SCOR (Cp′ = C5H5, ButC5H4,1,3-Bu2tC5H3; R = alkyl,aryl)

The kinetics of the photolytic CO-substitution of CpFe(CO)₂SCOR [Cp = C₅H₅, Bu ^t C₅H₄, 1,3-Bu₂ ^t C₅H₃; R = Me, Bu ^t , Ph, 2-(O₂N)C₆H₄, 3-(O₂N)C₆H₄, 4-(O₂N)C₆H₄, 3,5-(O₂N)₂C₆H₃] with PPh₃ were studied in CH₂Cl₂ at 0 °C by i.r. spectroscopy. The reactions yielded exclusively the mono-CO-substituted derivatives, CpFe-(CO)(PPh₃) SCOR, and were found to follow second order kinetics with first order dependence on the concentration of each reactant. The differences in rates are discussed in terms of current knowledge pertaining to such reactions. An associative mechanism is proposed to account for the kinetic data of the reactions described.     

Synthesis of RE Y zeolite for formulation of FCC catalyst and the catalytic performance in cracking of n-hexadecane

Research on Chemical Intermediates - This study presents the synthesis of rare earth-doped Y (RE Y) zeolite, its application in formulation of a fluid catalytic cracking (FCC) catalyst and the...     

Dilectric and thermal properties of PEO doped with cadimium chloride salt

The main aim of this research is to investigate the effect of salt concentration on the dielectric properties(AC (σ_AC),permittivity（ε′）,dielectric loss（ε″）,and dielectric relaxation process) and melting behavior of polyethylene oxide （PEO）/CdCl₂ complexes.The dielectric study was carried out over a frequency range 10-335 kHz and a temperature range 25-45℃.The AC conductivity,permittivity and dielectric loss of the PEO/CdCl₂ complexes increase with increasing salt concentration and temperature.Also,it was found that the addition of CdCl₂ salt to PEO host reduced the melting temperature of PEO host.Dielectric results reveal that the relaxation process of these complexes is due to viscoelastic relaxation or non-Debye relaxation at room temperature.Additionally,it was found that relaxation behavior remained viscoelastic at different temperatures and salt concentrations.     

Imide and anhydride bridged organoiron dinuclear homo and hetero dichalcogeno carboxylate complexes [CpFe(CO)2ECO(C6H4)CO]2NH and [CpFe(CO)2ECO(C6H4)CO]2O; E = S,Se

Organoiron thio- and seleno-terephthaloyl chloride complexes CpFe(CO)₂ECO(C₆H₄)COCl (E = S and Se) react with NaOH and NaNH₂ to give quantitative yields of the acid Cp(CO)₂ECO(C₆H₄)CO₂H and the amide CpFe(CO)₂ECO(C₆H₄)CONH₂ respectively. These amide and acid derivatives react with the terephthaloyl chloride complexes to give a new series of imide-bridged [CpFe(CO)₂ECO(C₆H₄)CO]₂NH and anhydride-bridged [CpFe(CO)₂ECO(C₆H₄)CO]₂O organoiron dinuclear homo and hetero dichalcogeno terephthalate complexes. The complexes were characterized by elemental analysis, i.r. and ¹H-n.m.r. spectra. This revised version was published online in June 2006 with corrections to the Cover Date.     

Syntheses of Monomeric,Dimeric, and Trimeric Complexes of Tungsten(VI), (V), (IV), and (III) with the 1,4,7-Triazacyclononane (L) Ligand. Crystal Structures of Dimeric [W2L2(μ2?OH)2Br2]Br2 · 2H2O and of Trimeric [W3L3(μ3?0)(μ2-0)3][ZnBr4]2

Reactions of WL(CO)₃ (L = 1, 4, 7-triazacyclononane; C₆H₁₅N₃) with bromine under different conditions afford the monomeric W^VI compound, WO₂LBr₂, or the monomeric W^V complex, WOLBr₃. The former dimerizes in aqueous solution, yielding the [W₂O₅L₂]²⁺ cation. Two diamagnetic isomers of the W^V -dimer, [W₂O₄L₂]²⁺, have been prepared : a yellow form with terminal oxo groups in cis-positions with respect to each other and a red species containing two terminal oxo-groups in trans-positions. The cationic W^IV -trinuclear cluster, [W₃O₄L₃]⁴⁺, has been isolated as the tetrabromozincate(2-) salt and its structure has been determined by single crystal X-ray diffraction. [W₃O₄L₃][ZnBr₄]₂ crystallizes in the monoclinic space group P2₁/c with a = 12.698(2) Å, b = 21.267(6) Å, c = 15.687(7) Å, β = 92.94(3)⁰, and V = 4222 ų, d_ealed. = 2.79 g cm^?3 for Z = 4, and mol wt 1773.2. The structure was solved by direct methods using 7399 unique reflections with I≥ 2.5 σ (I). Final residuals were R₁ = 0.089 and R₂ = 0.096. The structure consists of [W₃L₃O₄]⁴⁺ cations of the M₃X₁₃ cluster type and isolated ZnBr₄^2? anions. Three tungsten atoms occupy the corners of an equilateral triangle bridged by three μ₂-oxo- and one μ₃-oxo-ligands; each tungsten atom has a distorted octahedral environment of three oxygen and three nitrogen atoms. The short W - W distances of 2,52 Å and the diamagnetism indicate metal-metal bonding. The green, diamagnetic binuclear W_III complex, [W₂L₂(μ? OH)₂Br₂]Br₂ · 2 H₂O, has been prepared by reduction of monomeric WLOBr₃ in strongly acidic solution with zinc powder. The complex has been characterized by a single-crystal X-ray diffraction study; it crystallized in the orthorhombic space group Pnnm with a = 13.837(5) Å, b = 11.657(6) Å, c = 7.832 Å, and V = 1263 ų, d_calcd. = 2.67 g cm^?3 for Z = 2, and mol wt 1015.8. The structure was solved by direct methods using 783 unique reflections with I ? 2.5 σ(1). Final residuals were R₁ = 0.062 and R₂ = 0.084. The structure consists of dimeric cations [W₂L₂(μ? OH)₂Br₂]²⁺, bromide anions and molecules of water of crystallization. The tungsten centers are in a distorted octahedral environment of the tridentate N-donor igand, one coordinated bromide and two μ₂-hydroxo bridges (edge sharing), respectively. The bromide ligands are in trans-positions with respect to each other. The four-membered W₂(μ? OH)₂ ring is planar. The W? W distance of 2.477(3) Å together with its diamagnetism imply the presence of a strong metal-metal bond between the tungsten(II1) centers (σ²π²δ²).     

The reaction of 2-azaallenium salts with carbodiimides and tert-butyl isocyanide

2-Azaallenium salts $\text{1}$ react with diisopropyl carbodiimide to afford the formal dihydro-1,3-diazetium salts $\text{5}$. The structure of $\text{5c}$ has been confirmed by an X-ray diffraction analysis. With the carbodiimide $\text{2e}$ the tetraphenyl-2-azaallenium salt $\text{1a}$ reacts to give the guanidinium compound $\text{6}$.The diazetium salts $\text{5}$ react with further carbodiimide to afford the formal 2-azaallenium salts $\text{11}$. With tert-butyl isocyanide the 2-azaallenium salts $\text{1}$ undergo an Ugi reaction to yield the nitriles $\text{14}$.