A biased bimetallic Fe-Fe complex Cp*Fe(dppe)(C≡CFc) (1) was synthesized from FcC≡CH (Fc=C5H4FeC5H5) and Cp*Fe(dppe)Cl (Cp*=C5Me5). Its one-electron oxidation species [Cp*Fe(dppe)(C≡CFc)][PF6] (1a) was also prepared and the spectroscopic properties of 1a was studied. The single-crystal X-ray diffraction analysis of 1 shows that ferrocenylacetylene is bonded at the terminal carbon to the iron center in the Cp*Fe(dppe) part. Crystallographic data for 1: monoclinic, space group C2/c, with a=4.067 65(14) nm, b=1.260 74(4) nm, c=1.649 89(5) nm, β=104.387(10)°, V=8.195 7(5) nm3, Z=8, Dc=1.354 g·cm-3, F(000)=3512, μ=0.822 mm-1. The structure was refined to R1=0.038 4, wR2=0.100 0. CCDC: 234893. 相似文献
The 1,5‐benzodiazepine ring system exhibits a puckered boat‐like conformation for all four title compounds [4‐(2‐hydroxyphenyl)‐2‐phenyl‐2,3‐dihydro‐1H‐1,5‐benzodiazepine, C21H18N2O, (I), 2‐(2,3‐dimethoxyphenyl)‐4‐(2‐hydroxyphenyl)‐2,3‐dihydro‐1H‐1,5‐benzodiazepine, C23H22N2O3, (II), 2‐(3,4‐dimethoxyphenyl)‐4‐(2‐hydroxyphenyl)‐2,3‐dihydro‐1H‐1,5‐benzodiazepine, C23H22N2O3, (III), and 2‐(2,5‐dimethoxyphenyl)‐4‐(2‐hydroxyphenyl)‐2,3‐dihydro‐1H‐1,5‐benzodiazepine, C23H22N2O3, (IV)]. The stereochemical correlation of the two C6 aromatic groups with respect to the benzodiazepine ring system is pseudo‐equatorial–equatorial for compounds (I) (the phenyl group), (II) (the 2,3‐dimethoxyphenyl group) and (III) (the 3,4‐dimethoxyphenyl group), while for (IV) (the 2,5‐dimethoxyphenyl group) the system is pseudo‐axial–equatorial. An intramolecular hydrogen bond between the hydroxyl OH group and a benzodiazepine N atom is present for all four compounds and defines a six‐membered ring, whose geometry is constant across the series. Although the molecular structures are similar, the supramolecular packing is different; compounds (I) and (IV) form chains, while (II) forms dimeric units and (III) displays a layered structure. The packing seems to depend on at least two factors: (i) the nature of the atoms defining the hydrogen bond and (ii) the number of intermolecular interactions of the types O—H...O, N—H...O, N—H...π(arene) or C—H...π(arene). 相似文献
The melting temperature of ice I(h) for several commonly used models of water (SPC, SPC/E,TIP3P,TIP4P, TIP4P/Ew, and TIP5P) is obtained from computer simulations at p = 1 bar. Since the melting temperature of ice I(h) for the TIP4P model is now known [E. Sanz, C. Vega, J. L. F. Abascal, and L. G. MacDowell, Phys. Rev. Lett. 92, 255701 (2004)], it is possible to use the Gibbs-Duhem methodology [D. Kofke, J. Chem. Phys. 98, 4149 (1993)] to evaluate the melting temperature of ice I(h) for other potential models of water. We have found that the melting temperatures of ice I(h) for SPC, SPC/E, TIP3P, TIP4P, TIP4P/Ew, and TIP5P models are T = 190 K, 215 K, 146 K, 232 K, 245 K, and 274 K, respectively. The relative stability of ice I(h) with respect to ice II for these models has also been considered. It turns out that for SPC, SPC/E, TIP3P, and TIP5P the stable phase at the normal melting point is ice II (so that ice I(h) is not a thermodynamically stable phase for these models). For TIP4P and TIP4P/Ew, ice I(h) is the stable solid phase at the standard melting point. The location of the negative charge along the H-O-H bisector appears as a critical factor in the determination of the relative stability between the I(h) and II ice forms. The methodology proposed in this paper can be used to investigate the effect upon a coexistence line due to a change in the potential parameters. 相似文献
The components of synthesis gas, CO, H2, and CO2, may be converted into CH4 biologically through either acetate or H2/CO2 as intermediates. Of these two routes, conversion through H2/CO2 is preferred. This paper presents results of mixed-culture studies employing the photosynthetic bacteriumR. rubrum for converting CO to CO2 and H2 by the water gas shift reaction and two methanogens,M. formicicum andM. barkeri, for converting CO2 and H2 into CH4. Results are presented for triculture operation in two types of reactors, the packed bubble column and the trickle-bed reactor. 相似文献
The synthesis of the title compounds was carried out by cyclization via isocyanate of (E)-4,5-dihydro-10H-benzo[5,6]cyclohepta[1,2-b]-thiophene-10-ylideneacetic acid and 4,5-dihydro-10H-benzo[5,6]cyclohepta[1,2-b]-thiophene-10-ylacetic acid respectively, which were obtained by the Wadsworth-Emmons modification of the Wittig reaction of 4,5-dihydro-10H-10-oxobenzo[5,6]cyclohepta[1,2-b]thiophene and triethyl phosphonacetate. The structures of these new compounds are described. 相似文献
The crystal structures of molecular complexes betweenmeso- 1,2-diphenyl-1,2-ethanediol and two bisimines (N,N-(dibenzylidene)-ethylenediamine and glyoxylidene-bis(2,4-dimethyl-3-pentyl-amine) are reported at different temperatures. The structure-determining motif of the cocrystalline arrangement is one single O-H . N hydrogen bond resulting in infinite ladderlike polymers. The supramolecular structure is formed by recognition of fitting species: Thed- orl-isomers do not arrange in such structures.1H NMR experiments show that no prearrangements take place by forming complexes in solution. 相似文献
Environmental conditions affect the production of extracellular polysaccharide by Azotobacter chroococcum ATCC 4412. Production of exocellular polymer from a variety of carbon sources depended on the air flow rate. A high sucrose concentration in medium (8%) markedly favored expopolysaccharide production, which reached 14 g/L in about 72 h. In cell suspensions incubated in the presence of 8% sucrose in a nitrogen-free medium, biopolymer final concentration of 9 g/L corresponds to 68 g/g biomass. Maximum efficiency of sucrose conversion into exopolysaccharide peaked at 70% for initial disaccharide concentration of 6%. High performance liquid chromatography and gas liquid chromatography of acid hydrolysates of the exopolymer revealed the presence of mannuronosyl, guluronosyl, and acetyl residues, but not neutral sugars. The infrared spectrum corroborated the presence of carboxylate anions and O-acetyl groups in the exopolymer. Though the presence of more than one kind of polysaccharide cannot be ruled out, these data suggest that, under the experimental conditions used in this work, only a type of alginate-like exopolysaccharide is produced by A. chroococcum ATCC 4412. 相似文献
A routing R of a graph G is a set of n(n ? 1) elementary paths R(u, v) specified for all ordered pairs (u, v) of vertices of G. The vertex-forwarding index ξ(G) of G, is defined by Where ξ(G, R) is the maximum number of paths of the routing R passing through any vertex of G and the minimum is taken over all the routings of G. Let Gp denote the random graph on n vertices with edge probability p and let m = np. It is proved among other things that, under natural growth conditions on the function p = p(n), the ratio Tends to 1 in probability as n tends to infinity. 相似文献