The standard classical expression of the state-resolved photodissociation cross section is not consistent with an efficient Bohr quantization of product internal motions. A new and strictly equivalent expression not suffering from this drawback is proposed. This expression opens the way to more realistic classical simulations of direct polyatomic photodissociations in the quantum regime where only a few states are available to the products. 相似文献
Feel the pinch! Planar–chiral, cationic, ruthenium–palladium complexes based on η6,η1‐coordinated ECE′ pincer ligands are synthesized as racemic mixtures by reacting ECE′–palladium complexes and [Ru(C5R5)(MeCN)3]+ arenophiles (R=H or Me). Chiral resolution of the cationic complexes was achieved by using the chiral counterion [Δ‐TRISPHAT]?, and solving the X‐ray crystal structure of one diastereoisomer (shown here).
Fragment partitions of fragmenting hot nuclei produced in central and semiperipheral collisions have been compared in the excitation energy region 4-10?MeV per nucleon where radial collective expansion takes place. It is shown that, for a given total excitation energy per nucleon, the amount of radial collective energy fixes the mean fragment multiplicity. It is also shown that, at a given total excitation energy per nucleon, the different properties of fragment partitions are completely determined by the reduced fragment multiplicity (i.e., normalized to the source size). Freeze-out volumes seem to play a role in the scalings observed. 相似文献
Herein the first example of the iron(II)‐catalyzed trifluoromethylation of enamide using mild and simple reaction conditions is reported. The method is cost‐effective and uses the easy‐to‐handle Togni’s reagent as the electrophilic CF3 source. This transformation is totally regioselective at the C3 position of enamides and exhibits broad substrate scope, good functional group tolerance and thus demonstrates its useful application in a late‐stage fluorination strategy. 相似文献
The fixed-dose combination artesunate (AS)–amodiaquine (AQ) is one of the most widely used treatments for uncomplicated falciparum malaria. It is currently proposed to the inclusion in the model list of essential medicines of World Health Organization and has been recently prequalified. Until now, no satisfactory method for the simultaneous determination of the two active ingredients had been available. Thus, a reversed phase high performance liquid chromatography for the quantitative determination of AQ and AS was developed and validated. Chromatography was performed using an end-capped octadecylsilyl silica gel column (100 × 4.6 mm, 3 μm) with a binary gradient using aqueous phase containing potassium dihydrogen phosphate (10 mM) and acetonitrile. Taking into consideration the physico-chemical characteristics of the two compounds related to their ionization, the use of a counter ion was necessary to ensure the retention of AQ in a reversed phase system simultaneously to AS. Thus, aqueous mobile phase was adjusted to pH 3.0 and the chosen counter ion was sodium 1-octanesulfonate (100 mM). In these conditions, the retention times were about 4 min for AQ and 10 min for AS with UV detection at 300 and 210 nm, respectively. Method was then validated according to ICH guideline (specificity/linearity/accuracy/precision) and potential interferences with excipients and degradation products were checked. It has also been used for an interlaboratory study involving seven African National Quality Control Laboratories and Afssaps (Agence française de sécurité sanitaire des produits de santé) laboratory. The results demonstrate that this rapid and simple method can be easily used by official laboratories for routine control, market survey and for the detection of potential substandard medicines which are very frequent in African countries.
The title compound is Ru3(-Cl)2(CO)8(PPh3)2. Crystal data: formula C44H30O8Cl2P2Ru3;fw=1122.9; monoclinic,P21; cell parameters (at 293 K)a=10.971(2) Å,b=17.066(2) Å,c=11.833(2) Å,=92.91(1)°,V=2213 Å3,Z=2,
calcd=1.68,
meas=1.68. Final discrepancy indices areR(F)=0.030,RW(F)=0.036. The structure consists of an open trinuclear unit involving two metal-metal bonds [Ru(1)-Ru(2)=2.845(1) Å, Ru(2)-Ru(3)=2.860(1) Å]. The open edge of the metal framework [Ru(1)Ru(3)=3.254(1) Å] is supported by two symmetric bridging chloride ligands [Cl(1)-Ru(1)=2.461(2) Å; Cl(1)-Ru(3)=2.464(2) Å; Cl(2)-Ru(1)=2.470(2) Å; Cl(2)-Ru(3)=2.472(2) Å]. Both phosphorus ligands are cis to the Cl atoms and trans to the unique ruthenium atom Ru(2). Geometric features of the edge dibridged complex are discussed. 相似文献
The title compound is (μ-H)Ru3(CO)7(μ-As(C6H5)CH2As(C6H5)2)((C6H5)2 AsCH2As(C6H5)2)·CH2C12. Crystal data: monoclinic,P21/n, cell parameters (X-ray)a=12.82(2) Å,b=22.91(2) Å,c=17.83(2) Å, β=99.1(3)°; (neutron)a=12.94(1) Å, β=22.95(2)Å,c=17.93(3)Å,β=99.55(5)°. The structure was solved from X-ray data. FinalR indices areR(F)=0.051,Rw(F)=0.049 (X-ray);R(F)=0.064,Rw(F)=0.048,R(F2)=0.072,Rw(F2)=0.088 (neutron). The complex is derived from Ru3(CO)8(dpam)2 through reaction with hydrogen. The structure consists of a triangular array of metal atoms involving three metal-metal bonds[Ru(1)?Ru(2)=2.912(7)Å;Ru(1)?Ru(3)=2.829(3) A; Ru(2)?Ru(3)=2.845(6) Å]. The metal-metal edge Ru(1)?Ru(2) is supported by a bridging bis(diphenylarsino)methane ligand which lies in the equatorial plane. Activation of the second dpam ligand has generated the new face-bridging ligand unit μ-As(C6H5)CH2As(C6H5)2. In this unit, the bridgehead As atom spans over the Ru(1)?Ru(2) bond, while the second As atom is only bonded to Ru(3). The metal environment is achieved by CO ligands. The hydride ligand is bridging the Ru(1)?Ru(2) vector [Ru(1)?H=1.791(10) Å; Ru(2)?H=1.818(8) Å]. Geometric features of the dibridged Ru(μ-H)(μ-As)Ru bond are discussed. 相似文献
This paper presents a series solution for the homogenization problem of a linear viscoelastic periodic incompressible composite. The method uses the Laplace transform and the correspondence principle which are combined with the classical expansion along Neumann series of the solution of the periodic elasticity problem in Fourier space. The terms of the Neumann series appear as decoupled, containing geometry dependent terms and viscoelastic properties dependent terms which are polynomial fractions whose inverse Laplace transforms are provided explicitly. 相似文献