Cobalt(II) complexes with 2-aminoacetophenone thiosemicarbazone and three N(4)-substituted thiosemicarbazones have been prepared in EtOH solution and characterized by physical and spectral methods. I.r. and electronic spectra of the thiosemicarbazones and their complexes, along with physical properties of the complexes, have been obtained. The 2-aminoacetophenone thiosemicarbazones coordinate both as neutral and anionic ligands via the thiosemicarbazone moiety's imine nitrogen and thione/thiolato sulfur [on loss of the N(2) hydrogen]. 相似文献
The time decay of correlation for Brownian motion in a one-dimensional periodic potential and for large viscosity is studied analytically in an asymptotic method. The result is related to the dynamics of an overdamped sine-Gordon chain. The relevance of our finding to the superionic conduction phenomena is discussed. 相似文献
Small angle X-ray scattering has been utilised to study the structure of hematite aggregates. The small angle X-ray scattering (SAXS) spectra obtained provided insight into structure of the hematite aggregates and the size of the primary particles. The structural analysis results obtained by SAXS are consistent with previous results obtained from static light scattering studies. Both techniques indicate that the mass fractal dimensions of hematite aggregates are markedly higher than those obtained for other particle systems. 相似文献
The synthesis of a new class of spiro[tetrahydronaphthalen-one/butenolide]pyrrolidines has been accomplished by the 1,3-dipolar cycloaddition of azomethine ylide generated by thermal ring opening of cis-3-benzoyl-1-cyclohexyl-2-phenylaziridine with (E)-2-arylidene-1,2,3,4-tetrahydronaphthalen-1-ones and (E)-3-arylidene-5-phenyl-Δ4,5-butenolides. The structures of the products were confirmed by spectroscopic techniques as well as single crystal X-ray analysis of one of the products. 相似文献
Halide abstraction from [(Ph3P)2Rh(μ‐Cl)]2 by the sodium salt of the weakly coordinating [BArf4]? anion [Arf = C6H3(CF3)2‐3,5] in the presence of excess arene offers a convenient, high‐yielding route to the half‐sandwich cations [(arene)Rh(PPh3)2]+[BArf4]? [arene = benzene ( 1 ), toluene ( 2 )]. Crystalline samples of 1 and 2 are isomorphous [a = 13.1270(2), b = 15.3030(2), c = 17.5760(3) Å, α = 74.620(1), β = 81.533(1), γ = 88.540(1)° for 1 ] and feature the arene ligand bound to the rhodium atom in η6 fashion. 相似文献
Kinetic properties of pig heart citrate synthase immobilized on Sepharose were determined. Compared to the free enzyme the Km values for both acetyl-CoA and oxalacetate were increased. The kinetic pattern of the Lineweaver-Burk plots of both substrates for the immobilized enzyme was that of lines intersecting on thex axis. This is the same as that obtained for the free enzyme and indicates that there is no change in the kinetic mechanism of the reaction. The pH response and the Arrhenius plot of both the immobilized and free enzyme were the same. The enzymes show a break in their Arrhenius plots. The immobilized enzyme exhibits greater heat stability than does the free enzyme. 相似文献
In CO2 transformation catalysis, the synthesis of cyclic carbonates using two classes of MOF catalysts viz., zeolitic imidazolate frameworks (ZIF) and MOFs with carboxylate-capped SBUs have gained large attention. Herein we propose the strategy of employing a unified multifunctional framework formed in the metal-centered assembly of imidazole and amino-carboxylates for CO2 transformation, such as propylene carbonate (PC) by the cycloaddition of CO2 with propylene oxide. The framework {[Cu(L-asp)(1,4-bix)0.5]·3H2O}n (CuAspBix) comprises of the amino acid building units, L-aspartic acid (L-Asp) and the flexible ligand, 1,4-bis(imidazole-1-yl methyl)benzene [1,4-Bix]. The 1,4-Bix ligand with imidazole terminals renders elongated M-M distances and flexibility in comparison with pristine ZIF materials. The cumbersome synthesis procedure poor phase purity of the bulk catalyst in solvothermal conditions were improved by a microwave-assisted synthesis, preserving the structural and physicochemical properties. Minimal energy input or room temperatures for the catalysis occurred via the synergistic participation of CuAspBix and quaternary ammonium bromide salt, demonstrated by density-functional theory computational studies to propose mechanistic pathway of the reaction. Reaction conditions were optimized by altering the parameters. The heterogeneous catalyst was reused four times without a significant change in activity.
The reactivities of the highly electrophilic boranes ClB(C(6)F(5))(2) (1) and [HB(C(6)F(5))(2)](n) (2) towards a range of organometallic reagents featuring metals from Groups 7-10 have been investigated. Salt elimination chemistry is observed 1 between and the nucleophilic anions eta(5)-C(5)R(5))Fe(CO)(2)](-)(R = H or Me) and [Mn(CO)(5)](-), leading to the generation of the novel boryl complexes (eta(5)-C(5)R(5))Fe(CO)(2)B(C(6)F(5))(2)[R = H (3) or Me (4)] and (OC)(5)MnB(C(6)F(5))(2) (5). Such systems are designed to probe the extent to which the strongly sigma-donor boryl ligand can also act as a pi-acceptor; a variety of spectroscopic, structural and computational probes imply that even with such strongly electron withdrawing boryl substituents, the pi component of the metal-boron linkage is a relatively minor one. Similar reactivity is observed towards the hydridomanganese anion [(eta(5)-C(5)H(4)Me)Mn(CO)(2)H](-), generating a thermally labile product identified spectroscopically as (eta(5)-C(5)H(4)Me)Mn(CO)(2)(H)B(C(6)F(5))(2) (6). Boranes 1 and 2 display different patterns of reactivity towards low-valent platinum and rhodium complexes than those demonstrated previously for less electrophilic reagents. Thus, reaction of 1 with (Ph(3)P)(2)Pt(H(2)C=CH(2)) ultimately generates EtB(C(6)F(5))(2) (10) as the major boron-containing product, together with cis-(Ph(3)P)(2)PtCl(2) and trans-(Ph(3)P)(2)Pt(C(6)F(5))Cl (9). The cationic platinum hydride [(Ph(3)P)(3)PtH](+) is identified as an intermediate in the reaction pathway. Reaction of with [(Ph(3)P)(2)Rh(mu-Cl)](2), in toluene on the other hand, appears to proceed via ligand abstraction with both Ph(3)P.HB(C(6)F(5))(2) (11) and the arene rhodium(I) cation [(Ph(3)P)(2)Rh(eta(6)-C(6)H(5)Me)](+) (14) ultimately being formed. 相似文献