Reaction of 2,6-dibenzylidenecyclohexanone with phosphorus pentachloride: Triple functionalization of the isosemiquinoid system

The reaction of 2,6-dibenzylidenecyclohexanone with PCl₅ occursvia the sequential stages of desoxychlorination and substitutional phosphorylation to form (after oxidation, methoxylation, and hydrolysis on the surface of the chromatographic SiO₂ adsorbent) organophosphorus products of the 1-(a-chloro-, a-hydroxy-, or -alkoxy)benzyl-2-chloro-3-(-(dimethylphosphoryl)benzylidene)cyclobex-1-ene series.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 441–443, February, 1996.     

Time-resolved X-ray diffraction study of the transition of an amorphous TiCu alloy to the crystalline state

The transition of the TiCu alloy from an amorphous state to the crystalline state has been studied by time-resolved X-ray diffraction. An analysis of the diffraction pattern has shown that the crystallization of the amorphous TiCu alloy upon heating occurs for a short time (no longer than 0.5 s). A sharp transition is observed at the instant of crystallization, at which the intensity of the total diffraction pattern background decreases and diffraction lines of the crystalline phase γ-TiCu arise. No intermediate crystalline phases are observed. The change in the alloy structure is accompanied by the exothermic thermal effect. The kinetics of the change in the total intensity of the diffraction spectrum in the period preceding the crystallization is nonmonotonic. Ten seconds before the occurrence of diffraction lines of the γ-TiCu phase at 300°C, the integrated spectral intensity decreases. The effect observed is related to the relaxation processes in the amorphous state and the onset of formation of long-range structural order.     

Isolation and Hydrogenation of a Complex with a Terminal Iridium–Nitrido Bond

An N for Ir : The synthesis and X‐ray crystal structure of a late‐transition‐metal complex with a terminal nitrido ligand and its hydrogenation to the related amido complex are reported (see scheme).

     

Heterotrimetallic Mixed-Valent Molecular Precursors Containing Periodic Table Neighbors: Assignment of Metal Positions and Oxidation States

A known trinuclear structure was used to design the heterobimetallic mixed-valent, mixed-ligand molecule [Co^II(hfac)₃−Na−Co^III(acac)₃] ( 1 ). This was used as a template structure to develop heterotrimetallic molecules [Co^II(hfac)₃−Na−Fe^III(acac)₃] ( 2 ) and [Ni^II(hfac)₃−Na−Co^III(acac)₃] ( 3 ) via isovalent site-specific substitution at either of the cobalt positions. Diffraction methods, synchrotron resonant diffraction, and multiple-wavelength anomalous diffraction were applied beyond simple structural investigation to provide an unambiguous assignment of the positions and oxidation states for the periodic table neighbors in the heterometallic assemblies. Molecules of 2 and 3 are true heterotrimetallic rather than a statistical mixture of two heterobimetallic counterparts. Trinuclear platform 1 exhibits flexibility in accommodating a variety of di- and trivalent metals, which can be further utilized in the design of molecular precursors for the NaMM′O₄ functional oxide materials.     

Structure and tribological properties of Cu–PU–PTFE composite coatings prepared by low‐energy electron beam dispersion with glow discharge

Polytetrafluoroethylene (PTFE) composite coatings doped copper acetate and polyurethane (PU) were prepared on rubber substrate by low‐energy electron beam dispersion technique. The effects of dopant and glow discharge treatment on the surface morphology, structure and tribological properties of the coatings were investigated. The results showed that Cu–PTFE composite coatings form uniform surface and dense column structure with spherical aggregations under glow discharge treatment. PU coating shows the large size of protuberance structure but PU–PTFE coating presents spherical structure. Both of the coatings become relative dense and smooth after discharge treatment, and Cu–PU–PTFE composite coatings possess a smoother surface and lower polar component of surface energy. Cu doping weakens the crystallinity and ordering degree of composite coatings, but glow discharge increases the ordering degree and branched structure of C―H groups. Friction experiment indicated that Cu fails to improve the wear resistance of PTFE coatings but glow discharge treatment can do it. Cu–PU–PTFE coatings after discharge treatment have the higher wear resistance and lower coefficient of friction. Copyright © 2016 John Wiley & Sons, Ltd.     

Structure and energy studies of β-diketonates. XIII. Molecular structure of gadolinium tris-hexafluoroacetylacetonate Gd(C5O2HF6)3

In a mass spectrometric study, it was found that the saturated vapor over gadolinium tris-hexafluoroacetylacetonate Gd(C₅O₂HF₆)₃ contains molecular forms with a mass exceeding the mass of the dimer. The vapor overheated to 250–300°C contains only the monomer form. Simultaneous electron diffraction and mass spectrometric experiment aimed at investigating the structure of the Gd(hfa)₃ monomer molecule was carried out at 284(5)°C. The Gd(hfa)₃ molecule was found to have the symmetry of the equilibrium D ₃ configuration. The basic structural parameters are r _h1(Gd-O) = 2.291(10) Å, r _h1(O-C) = 1.257(10) Å, r _h1(C-C_r) = 1.404(6) Å, r _h1(C_F-F)_av = 1.341(3) Å, ∠OGdO = 72.8(0.4)°. The GdO₆ coordination polyhedron has the structure of a distorted antiprism. The rotation angle of the O-O-O trigonal faces relative to their position in a regular prism is 18.7(0.9)°. Quantum chemical calculations (HF/SBK, 6-31G*) generally reproduce the experimental structure, but the Gd-O internuclear distance is exaggerated by 0.04 Å.