Ru(II)(η6-p-cymene) Complexes Supported on Linear Chiral and Achiral Poly(spirophosphazene-pyridine) Copolymers

The reaction in dichloromethane at room temperature of the polyspirophosphazene copolymer {[NP(O₂C₁₂H₈)]_0.7[NP(OC₅H₄N)₂]_0.3} _n (1) (O₂C₁₂H₈=2,2′dioxybiphenyl) with [Ru₂(η ⁶-p-cymene)₂Cl₄] gives the polymer supported organometallic complex {[NP(O₂C₁₂H₈)]_0.7[NP(OC₅H₄N-Ru(η ⁶-p-cymene)Cl₂)₂]_0.3} _n (2). Similarly the chiral phosphazene {[NP(O₂C₂₀H₁₂)]_0.9[NP(OC₅H₄N)₂]_0.1} _n (3) (O₂C₂₀H₁₂=R-2,2′-dioxy,1′1′-binaphthyl) reacts with the appropriate amount of the Ru precursor to give the related polymeric complex {[NP(O₂C₂₀H₁₂)]_0.9[NP(OC₅H₄N)(OC₅H₄N-Ru(η ⁶-p-cymene)Cl₂]_0.1} _n (4) as an orange solid. Carrying out the reaction of 3 with the Ru precursor in acetone at room temperature using 0.35 equivalents of Ru per pyridine site, gives the crosslinked yellow material with formula {[NP(O₂C₂₀H₁₂)]_0.9[NP(OC₅H₅N)₂]_0.1[Ru(η ⁶-p-cymene)Cl₂]_0.07]} _n (5), that may contain cationic [Ru(η ⁶-p-cymene)Cl]⁺ units trapped in the rigid interior of a chiral network.     

Surface Energy and Thermal Stability Studies of Poly(dimethyl siloxane)–Poly(alkyl(meth)acrylate) Copolymers

The correlation between the surface energy and thermal stability of polymers plays an important role in engineering of plastic materials. In this work, microstructural characteristics of copolymers of poly(dimethyl siloxane) with benzyl methacrylate, ethyl methacrylate, and methyl acrylate are correlated with their surface energy and thermal stability. The poly(dimethyl siloxane) segments in the copolymer chains affected the hydrophobic behavior. The surface energy of the synthesized copolymers decreased by increasing segments of alkyl methacrylates. The thermal stability of copolymers suggesting that heat resistance of poly(dimethyl siloxane) copolymers used in this correlation can be improved by adjusting the units of alkyl methacrylates in copolymers.     

Solvent/C60 exchange on Ir(CO)(PPH3)2(Cl)(η2-C60) and solvent/solvent’ exchange on Ir(CO)(PPH3)2(Cl)(solvent)

Dissociation of C₆₀ from Ir(CO)(PPh₃)₂(Cl)(η²-C₆₀) in a binary mixture of solvents (solvent₁ and solvent₂) produced non-equilibrium mixtures of Ir(CO)(PPh₃)₂(Cl)(solvent₁) and Ir(CO)(PPh₃)₂(Cl)(solvent₂). Once the solvated species were produced, they underwent a relative fast solvent exchange between them to produce an equilibrium mixture.     

Synthesis,Characterization of Fulvic Acid–Poly(Methylmethacrylate) Graft Copolymers Based on Surface-Initiated Atom Transfer Radical Polymerization and its Effect on Performance of Poly(Lactic Acid)

Fulvic acid–poly(methylmethacrylate) graft copolymers were synthesized by surface-initiated atom transfer radical polymerization with fulvic acid. The result demonstrated that the hydrophobicity of fulvic acid–poly(methylmethacrylate) was improved after modification by surface-initiated atom transfer radical polymerization. Furthermore, poly(lactic acid)/fulvic acid–poly(methylmethacrylate) composites were prepared to improve the performances of poly(lactic acid) by blend melting. Compared to poly(lactic acid) with X_c of 5.38%, the X_c of poly(lactic acid)/fulvic acid–poly(methylmethacrylate) composites was 19.94%. Moreover, the impact strength of poly(lactic acid)/fulvic acid–poly(methylmethacrylate) composites was increased by 5.19% compared to poly(lactic acid). In all, this study provided an effective and feasible method for optimizing interface performance and enhancing the thermal stability of poly(lactic acid).     

Metal-Ion Type Effect on the Crystal Structure and Optical Properties of 2,2′-bipyridine Complexes of Pb(II) and Cd(II)

To investigate the effect of metal ion type on the crystal structure and optical and thermal behaviors of coordination compounds, two homometal and one heterometal 2,2′-bipyridine complexes of Pb(II) and Cd(II) have been synthesized and characterized by elemental analysis, PXRD, FT-IR and single crystal X-ray diffraction. Crystal structure analysis of heterometal coordination polymer, [Pb₂Cd(2,2′-bipy)₄(NO₃)₆]_n, displays the attendance of a centrosymmetric 1D coordination polymer that crystallizes in the triclinic system with the space group of \({\text{p}}_{1}^{ - }\). Thermal behavior of prepared coordination compounds was examined under air atmosphere by thermogravimetric analysis. The study of optical properties of compounds showed that metal ion type of coordination compounds is influential on their photophysical properties. Moreover, heterometal coordination polymer was doped into a PVK:PBD blend in two different concentrations as a light emitting material in the fabrication of two organic light-emitting diodes.     

Synthesis and Characterization of Some Poly(1,2-Phenylenedithiocarbamate)–Metal Complexes

Poly(1,2-phenylenedithiocarbamate) (PPDTC) was prepared by the reaction of 2-aminothiophenol with carbon disulfide followed by condensation through the removal of H₂S gas. PPDTC was used as a ligand to prepare four poly(1,2-phenylenedithiocarbamate)–metal complexes of iron(II), cobalt(II), copper(II), and lead(II), by refluxing with the metal salts. The polymer and its metal complexes were investigated by elemental analyses, UV–visible and IR spectroscopy, inherent viscosity, and magnetic susceptibility. The DC electrical conductivity variation with the temperature in the range 298–498 K of PPDTC and its polymeric copper complex was measured. Both polymer and polymer metal complexes showed an increase in electrical conductivity with an increase in temperature: typical semiconductor behavior. The proposed structure of the complexes is (MLX₂·mH₂O) _n .     

The effect of [(η-C3H5)(η-C5H5)Mo(CO)2] on drying of solvent-borne alkyd paints

Allyl molybdenum complex [(η³-C₃H₅)(η⁵-C₅H₅)Mo(CO)₂] (Mo-A) was examined as a new drier for solvent-borne alkyd binder. The drying activity of pure Mo-A and the of combinations of Mo-A with cobalt(II) 2-ethylhexanoate (Co-Nuodex) was examined using standard methods for measurements of the drying time and hardness development of the alkyd film. The detailed study of the drying process was studied by time-resolved infrared spectroscopy on ethyl linoleate as well as on thin coating of alkyd binder.     

Cytotoxic organometallic [Ru(η6-anethole)(en)(X)]PF6 (X = Br or I) complexes: Synthesis,characterization and in vitro biological evaluation

Two new organometallic compounds with the general formula [Ru(η⁶-anethole)(en)(X)]PF₆, where X = Br (5) or I (6) and en = ethylenediamine, were synthesized and fully characterized using standard techniques (NMR, MS and elemental analysis). Displacement of the proton and carbon aromatic chemical shifts of anethole to the upper field in both compounds indicated organometallic Ru(η⁶-anethole) bond formation, and the characteristic “piano-stool” structure of these types of compounds was confirmed by the single crystal X-ray diffraction of compound 5. Compounds 5 and 6 exhibited interesting cytotoxicity, especially toward the human colon tumor cell line HT-29, similar to the previously studied compound [Ru(η⁶-anethole)(en)(Cl)]PF₆ (4). A slight tendency toward cytotoxicity could be observed by varying the halogen leaving group (IC₅₀ value): 6 (10 ± 2 μM) > 5 (18 ± 2 μM) = 4 (18 ± 3 μM). Compound 6 showed 3-fold more biological activity in HT-29 cells than toward the non-tumor colon cell line CCD-841, making it an interesting candidate for further studies and drug development.     

Visible light curing of bisphenol-A epoxides and acrylates photoinitiated by (η6-benzophenone)(η5-cyclopentadienyl) iron hexafluorophosphate

Visible light curing of diglycidyl ether of bisphenol-A (DGEBA) epoxy oligomer and acrylate monomers photoinitiated by (η⁶-benzophenone)(η⁵-cyclopentadienyl) iron hexafluorophosphate (Fc-BP) under a halogen lamp were studied by near infrared spectroscopy. Fc-BP exhibited high efficiency in the radical photopolymerization of acrylate monomers, even without the presence of tertiary amines. Under the same light source, however, benzophenone did not show any photoinitiating ability. Fc-BP could also be used to photoinitiate the cationic polymerization of DGEBA. There was an obvious increase in the photopolymerization rate of DGEBA and a decrease in the induction period when benzoyl peroxide was used as a photosensitizer. The induction period at the beginning of DGEBA cationic polymerization was eliminated by introducing a certain amount of cycloaliphatic epoxy monomer ERL4221 as an active diluent. However, the final epoxy conversion was decreased when ERL4221 was used.     

Methane coupling at low temperatures on Ru(0001) and Ru(11¯20) catalysts

The conversion of methane to higher hydrocarbons on single crystal Ru catalysts has been investigated using combined elevated-pressure kinetic measurements/surface science studies. The reaction consists of activation of methane on Ru(0001) and Ru(11¯20) surfaces to produce carbonaceous intermediates at temperatures between 350 and 700 K and rehydrogenation of these species to ethane and propane at 370 K. It is found that under the reaction conditions employed, the maximum yield in ethane/propane production occurs at 500 K on both surfaces. Influence of the hydrogenation temperature on the production of ethane and propane is also examined. On Ru(0001), the yields of ethane and propane maximize at = 400 K, whereas no maximum yield was observed on Ru(11 0) in the 300–500 K temperature range. Under optimum reaction conditions, hydrocarbon products consist of 16% ethane and 2% propane. High-resolution electron energy-loss spectroscopy (HREELS) has been used to identify various forms of hydrocarbonaceous intermediates following methane decomposition. An effort is made to relate the hydrocarbon intermediates identified by HREELS to the gas phase products observed in the elevated pressure experiments.     

Selective Photo-epoxidation of (R)-(+)- and (S)-(−)-Limonene by Chiral and Non-Chiral Dioxo-Mo(VI) Complexes Anchored on TiO2-Nanotubes

Topics in Catalysis - Selective epoxidation of the (R) and (S) isomers of limonene by dioxomolybdenum(VI) complexes anchored covalently on TiO2 nanotubes using UV–Vis light and O2 as the...     

Migratory insertion reaction in alkenyl ruthenium(II) complexes containing a trifluoroacetate ligand. X-ray structure of the Ru(η2- O2CCF3)(η1-OCCHCHtBu)(CO)(PPh3)2 complex

Reaction of compound Ru(O₂CCF₃)(CHCH^tBu)(CO)(PPh₃)₂ with CO gives the η¹-alkeneacyl complex Ru(O₂CCF₃)(OCCHCH^tBu)(CO)(PPh₃)₂, which is in equilibrium with the dicarbonyl Ru(O₂CCF₃)(CHCH^tBu)(CO)₂(PPh₃)₂ derivative in CH₂Cl₂ solution. The η¹-acyl form involves an η¹-coordination of the O₂CCF₃ ligand, whereas the dicarbonyl form contains the carboxylate ligand η²-coordinated to the metal. The same mixture of carbonylated compounds can be obtained from the reaction of Ru(CHCH^tBu)Cl(CO)₂(PPh₃)₂ with Na[O₂CCF₃] in a CH₂Cl₂/MeOH solution. These reactions reveal the significance of ancillary bidentate ligands for the η-nature of the acyl–metal bond. The molecular structure of the complex Ru(O₂CCF₃)(OCCHCH^tBu)(CO)(PPh₃)₂ was established by X-ray diffraction study of a monocrystal obtained from a CH₂Cl₂/MeOH solution of the mixture of carbonylated compounds.     

Effects of Poly(ϵ-caprolactone) on Structure and Properties of Poly(lactic acid)/Poly(ϵ-caprolactone) Meltblown Nonwoven

To obtain flexile poly(lactic acid)-based melt-blown nonwoven filtration material, poly(lactic acid)/poly(?-caprolactone) melt-blown nonwoven with various components were melt-spun by melt-blown processing in the Melt-blown Experiment Line. The 3 wt.% tributyl citrate to poly(?-caprolactone) was added in the composites as compatibilizer. The effect of poly(?-caprolactone) on the structure, morphology, mechanical and filtration properties of poly(lactic acid)/poly(?-caprolactone) melt-blown nonwoven was reported. Scanning electron microscopy micrographs revealed good dispersion of the additive in the fiber webs. The crystallinity of melt-blown webs with poly(?-caprolactone) was more than that of poly(lactic acid) alone. The tensile strength, ductility and air permeability of poly(lactic acid) melt-blown nonwovens were enhanced significantly. The input of poly(?-caprolactone) increased the diameter of fibers and decreased the filtration efficiency of poly(lactic acid)/poly(?-caprolactone) melt-blown nonwoven.     

Ru4(μ-CO)(CO)9(η4-μ4-C6H4)(η2-μ1,μ4-PPhCH2CH2PPh2): an unusual pyrolysis product of Ru3(CO)10(dppe) containing a benzyne ligand

The thermal decomposition of Ru₃(CO)₁₀(dppe) in refluxing benzene gives, in contrast to the pyrolysis of the dppm analogue, the tetranuclear cluster Ru₄(μ-CO)(CO)₉(η⁴-μ₄-C₆H₄)(η²-μ₁,μ₄-PCH₂CH₂PPh₂) (1) along with Ru₃(CO)₉(η²-μ₁,μ₂-C₆H₅)(η³-μ₁,μ₂-PPhCH₂CH₂PPh₂) (2). The single-crystal structure analysis of 1 reveals a square-planar tetraruthenium skeleton containing a η⁴-μ₄-benzyne ligand as well as a η²-μ₁,μ₄-phosphinidene–phosphine ligand.     

Diastereotopic relationship between planar and central chiralities in the formation of Ru(η3-allyl)(CO)(PPh3)(L–L′) complexes

Hydride ruthenium complexes, RuHCl(CO)(PPh₃)₂(L–L^′) 3 (L–L^′=bidentate ligand having nitrogen and oxygen) react with allenes to give Ru(η³-allyl)(CO)(PPh₃)(L–L^′) complexes 5 in good yields via hydrometalation reaction. The complexes 5 have planar chirality at the η³-allyl ligand and central chirality at the Ru metal, and consist of one pair of enantiomers. Ligand substitution reaction of Ru(η³-allyl)Cl(CO)(PPh₃)₂ complexes 6 with bidentate ligands (L–L^′) also afford the complexes 5 which have the same stereochemistry as those formed by the hydrometalation reaction. The planar chirality is controlled by the central chirality at the Ru metal in both the formations of the complexes 5. The structure of 5a (L–L^′=N–N bidentate ligand) was determined by the X-ray crystal structure analysis.     

Thermal dehydration of Y(TFA)3(H2O)3: Synthesis and molecular structures of [Y(μ,η1:η1-TFA)3(THF)(H2O)]1∞ · THF and [Y4(μ3-OH)4(μ,η1:η1-TFA)6(η1-TFA)(η2-TFA)(THF)3(DMSO)(H2O)] · 6THF (TFA = trifluoroacetate)

In order to obtain a better anhydrous precursor for various applications in materials science and catalysis, thermal dehydration reactions of Y(TFA)₃(H₂O)₃ (TFA = trifluoroacetate) (A) were investigated. Thermal treatment of A at different temperatures under vacuum (5 × 10^?2 mm) for several hours failed to give totally anhydrous yttrium trifluoroacetate (as indicated by IR). Two different complexes, a partially dehydrated [Y(μ,η¹:η¹-TFA)₃(THF)(H₂O)]_1∞·THF (1) and a partially hydrolyzed [Y₄(μ₃-OH)₄(μ,η¹:η¹-TFA)₆(η¹-TFA)(η²-TFA)(THF)₃(DMSO)(H₂O)] · 6THF (2), were obtained with good and moderate yield, respectively, by crystallization of two different thermally treated batches of A from THF (or THF + DMSO) at room temperature. More efficient dehydration of A could be achieved at 200 °C in a furnace, the obtained anhydrous yttrium tris-trifluoroacetate giving Y(TFA)₃(THF)₂ (3) on crystallization from THF. All the products were characterized by elemental analyses, FT-IR and ¹H NMR spectroscopy as well as thermo-gravimetric analysis. In addition, single crystal X-ray structures are reported for 1 and 2, which show either a terminal (η¹ and η²) or bridging (μ,η¹:η¹) bonding behavior of the TFA ligand.     

Pincer Type Ditertiary Aminomethylphosphine–Pd(II) Complexes Supported on Multi-Walled Carbon Nanotube: Catalytic Properties in Heck C–C Coupling Reactions

Pincer type aminomethylphosphine–Pd(II) complexes supported on multi-walled carbon nanotube (MWCNT) have been synthesized and characterized using X-Ray diffraction spectrometry, scanning electron microscopy, thermal analysis, energy dispersive X-Ray, Fourier transform infrared spectrometry, transmission electron microscopy (TEM) and ultraviolet–visible spectrometry techniques. The novel complexes were tried as catalysts in Heck C–C coupling reactions. The crystallite size and lattice strain of the MWCNT based compounds were calculated by the Scherrer’s equation. The optical parameters of the MWCNT based structures were analyzed and the band gap enhanced from 4.42 to 4.98 eV. Different solvents (toluene, 1,4-diooxane, DMF and NMP) and bases (Et₃N, Na₂CO₃, NaOAc and K₂CO₃) were tried at different temperatures (80, 100 and 110 °C) in the cross-coupling of bromobenzene with styrene. The optimum yield was found in the presence of K₂CO₃, 110 °C in 1,4-dioxane solvent system.     

Sulfur-assisted chloride and triphenylphosphine dissociation of palladium(II) complex [Pd(PPh3)2(η1-SCNMe2)(Cl)]. X-ray structures of [Pd(PPh3)2(η1-SCNMe2)(Cl)], [Pd(PPh3)(Cl)]2(μ,η2-SCNMe2)2, and [Pd(PPh3)2(η2-SCNMe2)][PF6]

Treatment of Pd(PPh₃)₄ with Me₂NC(S)Cl in dichloromethane at −20 °C produces the complex [Pd(PPh₃)₂(η¹-SCNMe₂)(Cl)], 2. Variable temperature ¹H and ³¹P{H} NMR experiments of complex 2 shows the dissociation of either the chloride or the triphenylphosphine ligand to form complex [Pd(PPh₃)₂(η²-SCNMe₂)][Cl], 3 or the dipalladium complex [Pd(PPh₃)Cl]₂(μ,η²-SCNMe₂)₂, 4. The reaction of complex 2 with NaPF₆ affords complex [Pd(PPh₃)₂(η²-SCNMe₂)][PF₆], 5. Complexes 2, 4, and 5 are characterized by X-ray diffraction analyses.     

Synthesis,spectral and antibacterial studies on Ni(II) and Zn(II) complexes involving N-furfuryl-N-isopropyldithiocarbamate (f iprdtc) and Lewis bases: X-ray structure of [Ni(f iprdtc)(NCS)(PPh3)]

[Ni(fⁱprdtc)₂] (1), [Ni(fⁱprdtc)(PPh₃)(NCS)] (2), [Ni(fⁱprdtc)(PPh₃)₂]ClO₄ (3), [Zn(fⁱprdtc)₂] (4), [Zn(fⁱprdtc)₂(1,10-phen)] (5) and [Zn(fⁱprdtc)₂(2,2′-bipy)] (6) (f ⁱprdtc=N-furfuryl-N-isopropyldithio- carbamate, 1,10-phen=1,10-phenanthroline and 2,2′-bipy=2,2′-bipyridine) complexes were prepared and characterized by elemental analysis, electronic, IR and NMR spectra and the structure of 2 was determined by single-crystal X-ray crystallography. UV–Vis spectral data of 1–3 are consistent with the formation of square planar complexes. IR spectra of the complexes show the contribution of the thioureide form to the structure. A single-crystal X-ray structural analysis of 2 proved four-coordinated nickel in a distorted square planar arrangement with a S₂PN donor set. Significant asymmetry in Ni–S bond distances was observed in [Ni? S1=2.1655(8); Ni? S2=2.2120(8) Å]. This observation clearly supports the less effective trans of SCN^? over PPh₃. The observed shielding in N¹³CS₂ chemical shifts of heteroleptic nickel complexes 2 and 3 when compared with homoleptic nickel complex 1 indicates the effect of PPh₃ on the mesomeric drift of electron density toward nickel through the thioureide C? N bond. The N¹³CS₂ chemical shift of 5 and 6 are additionally deshielded compared with 4 owing to the increase in coordination number. Complexes were screened for in vitro antibacterial activity and significant activity has been found.     

Cyclohexadiene-linked clusters: synthesis and molecular structure of [{Os4(CO)8(MeCCMe)(η6-C6H6)}2(μ2-η2:η2-C6H8-1,3)]

The reaction of [Os₄(CO)₉(RCCR)(η⁶-C₆H₆)] (R=Me, Ph) with Me₃NO in the presence of 1,3-cyclohexadiene or 1,4-cyclohexadiene yields the clusters [{Os₄(CO)₈(RCCR)(η⁶-C₆H₆)}₂(μ₂-η²:η²-C₆H₈-1,3)] and [{Os₄(CO)₈(RCCR)(η⁶-C₆H₆)}₂(μ₂-η²:η²-C₆H₈-1,4)], respectively. The molecular structure of [{Os₄(CO)₈(MeCCMe)(η⁶-C₆H₆)}₂(μ₂-η²:η²-C₆H₈-1,3)] has been determined by single crystal X-ray diffraction, and represents the first example of two osmium cluster fragments linked by 1,3-cyclohexadiene through a μ₂-η²:η²-bridge.