CF3O2自由基和NO反应机理的理论研究

用密度泛函理论(DFT)的B3LYP方法, 分别在6-31G、6-311G、6-311+G(d)基组水平上研究了CF3O2自由基和NO反应机理. 研究结果表明, CF3O2自由基和NO反应存在三条可行的反应通道, 优化得到了相应的中间体和过渡态. 从活化能看, 通道CH3O2+NO→IM1→TS1→IM2→TS2→CF3O+ONO的活化能最低, 仅为70.86 kJ•mol-1, 是主要反应通道, 主要产物是CF3O和NO2. 而通道CH3O2+NO→IM1→TS3→CF3ONO2和CH3O2+NO→TS4→IM3→TS5→IM4→TS6→CF3O+NOO的活化能较高, 故该反应难以进行.     

Transmetallation reactions of [Sn(R)2(Ph2PC6H4-2-S)2] with metal complexes of the Group 10: Stereoselective synthesis of cis-[M(Ph2PC6H4-2-S)2] (M=Ni, Pd, Pt)

The complexes cis-[M(Ph₂PC₆H₄-2-S)₂] M=Ni, Pd, Pt were stereoselectively synthesized by transmetallation reactions of [M(Cl)₂(NCC₆H₅)₂] M=Pd, Pt or NiCl₂·6H₂O with [Sn(R)₂(Ph₂PC₆H₄-2-S)₂] R=Ph, ⁿBu or ^tBu. The conformation of the Pd and Pt derivatives being unequivocally confirmed by single crystal X-ray diffraction studies showing both metal centers to be into a slightly distorted square planar environment, the main distortion being due to the steric hindrance caused by the aromatic rings in the phosphine moiety.     

Solvothermal syntheses of Cu3P via reactions of amorphous red phosphorus with a variety of copper sources

Polycrystalline Cu₃P was successfully prepared under a wide variety of solvothermal conditions. The reaction of red phosphorus with several copper sources (copper metal, copper (I) iodide, copper (I) chloride and copper (II) chloride) at 150-200 °C for 1-2 days in water produced Cu₃P. Products were examined with powder X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Thermal analyses and optical spectroscopy were also performed. A detailed list of reaction conditions, products and impurity phases (where applicable) are reported.     

Evolution of lowest singlet and triplet excited states with transition metals in group 10-12 metallaynes containing biphenyl spacer

A new series of thermally stable group 10 platinum(II) and group 12 mercury(II) poly-yne polymers containing biphenyl spacer trans-[-Pt(PBu₃)₂CC(p-C₆H₄)₂CC-]_n and [HgCC(p-C₆H₄)₂CC-]_n were prepared in good yields by Hagihara’s dehydrohalogenation reaction of the corresponding metal chloride precursors with 4,4′-diethynylbiphenyl HCC(p-C₆H₄)₂CCH at room temperature. We report the optical spectroscopy of these polymetallaynes and compare the results with their bimetallic model complexes trans-[Pt(Ph)(PEt₃)₂CC(p-C₆H₄)₂CCPt(Ph)(PEt₃)₂] and [MeHgCC(p-C₆H₄)₂CCHgMe] as well as the group 11 gold(I) counterpart [(PPh₃)AuCC(p-C₆H₄)₂CCAu(PPh₃)]. The structural properties of all model complexes have been studied by X-ray crystallography. The influence of the heavy metal atom in these metal alkynyl systems on the intersystem crossing rate and the spatial extent of lowest singlet and triplet excitons is systematically characterized. Our investigations indicate that the organic triplet emissions can be harvested by the heavy-atom effect of group 10-12 transition metals (viz., Pt, Au, and Hg) which enables efficient intersystem crossing from the S₁ singlet excited state to the T₁ triplet excited state.     

Transition metal clusters and supported species with metal-carbon bonds from first-principles quantum chemistry

We discuss the impact of density functional electronic structure calculations for understanding the organometallic chemistry of transition metal (TM) surface complexes and clusters. Examples will cover three types of systems, mainly of interest in the context of heterogeneous catalysis: (i) supported carbonyl complexes of rhenium on MgO and of rhodium in zeolites, (ii) TM clusters with CO ligands and adsorbates, and (iii) metal clusters exhibiting chemical bonds with atomic carbon. The first group of case studies promotes the concept that surface groups of oxide supports are bonded to TM complexes in the same way as common (poly-dentate) ligands are bonded in coordination compounds. The second group of examples demonstrates various “ligand effects” of TM clusters. Finally, we illustrate how carbido centers stabilize TM clusters and modify the propensity for adsorption at the surface of such clusters.     

GC investigation of olefins with chemically bonded gamma-mercaptopropylsilane-copper(II) complexes

Summary A column packing containing thiol groups chemically bonded to the silica surface was synthesized. The thiol functional groups were used as ligands capable of forming stable complexes with Cu(II). The prepared material was characterized by gas chromatography using unsaturated linear and branched hydrocarbons as well as cyclic and aromatic hydrocarbons. The occurrence of specific metal—olefin interactions resulting from the formation of -complexes during the chromatographic process was observed.Part IV of a series on transition metal complexes in GC. Part III see ref. [1].     

Wasserstoffbrücken in 1,1‐Bis(2‐hydroxyethyl)‐3‐benzoylthioharnstoff und seinen Nickel(II)‐ und Kupfer(II)‐Chelat‐Komplexen

Hydrogen Bonds in 1,1‐Bis(2‐hydroxyethyl)‐3‐benzoylthiourea and its Nickel(II)‐ and Copper(II)‐Chelate Complexes The ligand 1,1‐bis(2‐hydroxyethyl)‐3‐benzoylthiourea HL, ( 1 ), yields with nickel(II) and copper(II) ions neutral complexes [NiL₂], ( 2 ), and [CuL₂], ( 3 ). By X‐ray structure analysis and IR spectroscopy different intramolecular hydrogen bonds (OH…O) and (OH…N) could be identified in both equally coordinated ligands of the [NiL₂] molecule. For comparison X‐ray and IR data were also estimated for 1 and 3 .     

Selective catalytic monoreduction of dichlorooligosilanes with Grignard reagents

Transition metal-catalyzed monoreduction of dichlorooligosilanes with Grignard reagents is reported. Among the examined catalysts, group 4 metal chlorides such as TiCl₄ and Cp₂TiCl₂ gave the highest reactivity and good selectivity. The reducing power is effectively controlled by changing the catalysts and Grignard reagents to achieve sufficient selectivity depending on the oligosilane substrates.     

Sn Mössbauer spectroscopy of Gd0.8L0.2Mn6Sn6 and Tb0.8L0.2Mn6Sn6 compounds (L=Sc,Y, Lu)

The HfFe₆Ge₆-type compounds Gd_0.8L_0.2Mn₆Sn₆ and Tb_0.8L_0.2Mn₆Sn₆ (L = Sc, Y, Lu) have been studied by ¹¹⁹Sn Mössbauer spectroscopy. The values of the apparent quadrupolar splitting clearly evidence the easy plane magnetization of the gadolinium compounds and the easy axis one in the terbium compounds. The three tin sites behave differently with the nature and size of the substituting L element. For a given series, the hyperfine field of the Sn_2d site is almost unchanged whatever the size of the L element. The hyperfine field of the Sn_2e site strongly varies with the L size in relation with atomic displacements. The hyperfine field of the Sn_2c site exhibits a more complicated behavior. The field difference in the easy plane and easy axis compounds confirms the angle-dependent anisotropic contribution of the Mn moment to the hyperfine field. The analysis of the results also suggests the play of angle-dependent contributions arising from the rare earth moment.     

Magnetic,Mössbauer and optical spectroscopic properties of the AFe3O(PO4)3 (A = Ca,Sr, Pb) series of powder compounds

AFe₃O(PO₄)₃ (A = Ca, Sr and Pb) powder compounds were studied by means of X-ray diffraction (XRD), electron-probe microanalysis (EPMA) coupled with wavelength dispersion spectroscopy (WDS), Raman and diffuse reflectance spectroscopies, specific heat and magnetic properties measurements. Magnetization, magnetic susceptibility and specific heat measurements carried out on AFe₃O(PO₄)₃ (A = Sr, Ca and Pb) powders firmly establish a series of three ferromagnetic (FM)-like second order phase transitions spanned over the 32–8 K temperature range. Room temperature Mössbauer spectroscopy and associated DFT calculations confirm the existence of three crystallographically non equivalent Fe³⁺ sites in the three compounds. Mössbauer spectra recorded as a function of temperature in the PbFe₃O(PO₄)₃ compound also establishes the occurrence of two purely magnetic and reversible phase transitions at 32 and 10 K. Diffuse reflectance measurements reveal two broad absorption bands at 1047 and 837 nm, in both PbFe₃O(PO₄)₃ and SrFe₃O(PO₄)₃ powders, with peak cross sections ∼10⁻²⁰ cm² typical of spin-forbidden and forced electric dipole intraconfigurational transitions.