四卤化碳: 强碱反应体系顺磁共振研究

单电子转移反应是物理有机化学中十分活跃的研究领域之一,现已发现许多有机反应中都存在着单电子转移过程。探讨不同的单电子转移反应体系,了解其中电子给、受体之间的相互作用,不仅对深入了解反应机理有理论     

Synthese und Struktur von (NH4)2[(AuI4)(AuI2(μ2-I4))], einem Iodoaurat(III) mit I-Ionen als Liganden

Synthesis and Structure of (NH₄)₂[(AuI₄)(AuI₂(μ₂-I₄))], a Iodoaurate(III) with I₄^2? Anions as Ligands (NH₄)₂[(AuI₄)(AuI₂(μ₂-I₄))] is obtained in a sealed glass ampoule by slow cooling of a mixture of NH₄I, Au, and I₂ beforehand heated to 500°C. The compound forms black crystals decomposing slowly under loss of I₂. It crystallizes in the orthorhombic space group Pnma with a = 1357.7(1), b = 2169.9(2), c = 755.6(3) pm, and Z = 4. The crystal structure is built up by NH cations and square-planar [AuI₄]^? anions as well as [AuI₂(μ₂-I₄)]^? groups being linked together by the I ligands to form chains. The distances Au? I are in the range of 258.7(2) to 262.4(2) pm. The nearly linear I anions are characterized by a short central I? I distance of 270.9(3) pm and two longer outer distances of 338.7(2) pm.     

Substituent Effects on the Low-Frequency Vibrational Modes of Benzoic Acid and Related Compounds

Well-resolved absorption spectra of benzoic acid and its derivatives with one hydrogen atom replaced by a substituent group CH3, OH, NH2 or NO2 were reported in the frequency region between 6 and 67 cm^-1 at room temperature with terahertz time-domain spectroscopy （THz-TDS）. These substances can be distinguished easily based on the terahertz absorption spectra. The measurements suggested that even minor changes in the molecular configuration and chemical composition lead to distinct differences in THz spectrum. Density functional theory （DFT） method was used to assist the analysis and assignment of the individual THz absorption spectra of benzoic acid and its methyl derivatives. Observed THz responses of samples can be assigned to the collective vibrations associated with intermolecular hydrogen bonds.     

Electronic configuration assignment and the importance of low-lying excited states in high-spin imidazole-ligated iron(II) porphyrinates

The synthesis and characterization of six new high-spin deoxymyoglobin models (imidazole(tetraarylporphyrinato)iron(II)) are described. These have been intensively studied by temperature-dependent Mossbauer spectroscopy from 295 to 4.2 K. All complexes show a strong temperature dependence for the quadrupole splitting consistent with low-lying excited states of the same or lower multiplicity. An analysis of the data obtained in applied magnetic fields leads to the assignment of the sign of the quadrupole splitting. All model compounds as well as those of deoxymyoglobin and deoxyhemoglobin, previously studied, have a negative sign for the quadrupole splitting. Although not previously predicted, this experimental observation leads to the assignment of the ground-state electronic configuration for all high-spin imidazole-ligated iron(II) porphyrinates as (d(xz)())(2)(d(yz)())(1)(d(xy)())(1)(d(z)()()2)(1)(d(x)()()2(-)(y)()()2)(1). This is a distinctly different ground-state electronic configuration from other high-spin iron(II) porphyrinates; differences in structural details for the two classes of high-spin complexes are also discussed. The apparent anomaly of differing signs for the zero-field splitting constant between previously studied model complexes and the heme proteins is addressed; the difference appears to result from the fact that the assumptions used in the spin Hamiltonian approach that has been applied to these complexes are not adequately satisfied. Structures of four of the new five-coordinate species have been determined. Core conformations in these derivatives show variation, but these and previously studied compounds reveal a limited number of conformational patterns. The bond lengths and other geometrical parameters such as porphyrin core size and iron out-of-plane displacement support a high-spin state assignment for the iron(II).     

NO在Sm2—xSrxNiO4上的催化还原

在具有Ｋ２ＮｉＦ４型结构的Ｓｍ２－ｘＳｒｘＮｉＯ４（ｘ＝０．４，０．５，０．６，０．８，１．０，１．２，１．４，１．５）化合物上进行了ＣＯ催化还原ＮＯ的研究。结果表明，低温、低Ｓｒ＾２＋取借代量与高温、高Ｓｒ＾２＋取代量的反应途径不同，这可从化合物的结构、化合物中金属－氧键的标准生成焓的总和、ＮＯ还原的表现活化能及化合物上Ｏ２的脱附行为等得到解释。     

Supramolecular Assembling of Complex Tellurium Salts: Synthesis and Crystal Structures of {Cs[PhTeCl4]·CH3OH} and Cs[PhTeBr4]

The direct reaction between PhTeCl₃ and CsCl in methanol affords {Cs[PhTeCl₄]·CH₃OH}. Cs[PhTeBr₄] was prepared by refluxing [2‐Br‐C₅NH₅][PhTeBr₄] and CsCl in ethanol in the presence of an excess of HBr. In {Cs[PhTeCl₄]·CH₃OH} the [PhTeCl₄]^— units form dimers by secondary Te···Cl bonds with methanol molecules bridging adjacent Cs⁺ cations. In both compounds, the alkali metal cation interacts secondarily with the chlorine and bromine Te‐ligands, achieving singular coordination polyhedrons and holding the lattices in supramolecular tridimensional assemblies. The new complexes, {Cs[PhTeCl₄]·CH₃OH} and Cs[PhTeBr₄], crystallize in the space groups P2₁/c and P2₁/n, respectively. Only one such structure has been reported before.     

Structure and bonding in silver halides. A quantum chemical study of the monomers: Ag(2)X, AgX, AgX(2), and AgX(3) (X = F, Cl, Br, I)

The molecular structure of all silver halide monomers, Ag(2)X, AgX, AgX(2), and AgX(3), (X = F, Cl, Br, I), have been calculated at the B3LYP, MP2, and CCSD(T) levels of theory by using quasirelativistic pseudopotentials for all atoms except fluorine and chlorine. All silver monohalides are stable molecules, while the relative stabilities of the subhalides, dihalides, and trihalides considerably decrease toward the larger halogens. The ground-state structure of all Ag(2)X silver subhalides has C(2)(v)() symmetry, and the molecules can be best described as [Ag(2)](+)X(-). Silver dihalides are linear molecules; AgF(2) has a (2)Sigma(g) ground state, while all of the other silver dihalides have a ground state of (2)Pi(g) symmetry. The potential energy surface (PES) of all silver trihalides has been investigated. Neither of these molecules has a D(3)(h)() symmetric trigonal planar geometry, due to their Jahn-Teller distortion. The minimum energy structure of AgF(3) is a T-shaped structure with C(2)(v)() symmetry. For AgCl(3), AgBr(3), and AgI(3), the global minimum is an L-shaped structure, which lies outside the Jahn-Teller PES. This structure can be considered as a donor-acceptor system, with X(2) acting as donor and AgX as acceptor. Thus, except for AgF(3), in the other three silver trihalides, silver is not present in the formal oxidation state 3.     

B8N12簇的结构和振动光谱的理论研究

用量子化学从头计算方法研究Ｂ_８Ｎ_（１２）的几何构型、电子结构和振动光谱，讨论其稳定性和化学反应性质。