Infrared and Raman spectra of alkali halide/NO−3 systems

Detalled Raman spectra of the NO^?₃ ion substitutionally isolated in Rbl, Kl and KCl have been investigated at various temperatures between 77 and 300 K. These spectra, together with their corresponding infrared spectra, have been used to study the effective symmetry of these systems. Changes in the infrared and Raman activities of some of the modes of the NO^?₃ ions have been observed as the samples were cooled. Two different symmetries, one at room and the other at low temperature, have been identified as D₃ and C_3v respectively.     

Ruthenium(0) Catalyzed Isomerization of Allylbenzene. The Detection and Isolation of A Hydrido-η3-Allyl Intermediate

Allylbenzene is isomerized to $\text{cis}$- and $\text{trans}$-β-methylstyrene at 35–60°C in the presence of [(C₆H₅)₃P]₄Ru(π-CH₃CN)·CH₃CN. Two hydrido-η³-1-phenylallyl ruthenium complexes have been detected by proton nmr spectroscopy during the reaction and the predominant one of formula [(C₆H₅)₃P]₂RuH(η³-C₃H₄C₆H₅)(CH₃CN) has been isolated. The structure of this intermediate contains cis phosphines, mutually trans hydrido and acetonitrile ligands and the 1-phenylallyl ligand in a $\text{syn}$-configuration. A similar structure with an $\text{anti}$-configuration of the 1-phenylallyl ligand is suggested for the other detected intermediate. These complexes indicate that this isomerization is initiated by oxidative-addition of ruthenium(0) to an allylic C-H bond with the formation of distinct η³-allyl metal hydride species as has been proposed in a number of metal catalyzed olefin transformations.     

Determination of partial-wave inelasticities for elastic pion-nucleon scattering with the aid of experimental data on π N → ππ N processes in the beam-momentum range 300 < P beam < 500 MeV/ c

The partial-wave inelasticity parameters of the amplitude for elastic pion-nucleon scattering are determined with the aid of the phenomenological amplitude for inelastic πN → ππN processes in the energy range extending to the threshold for the production of two pions. The resulting inelasticity parameters are compared with their counterparts derived from modern partial-wave analyses. The largest inelastic-scattering cross section in the P11 wave is in excellent agreement with the analogous value from the analysis performed at the George Washington University in 2006. For other waves, however, the present results differ in the majority of cases from respective values given by partial-wave analyses (the distinctions are especially large for the isospin-3/2 amplitudes). Original Russian Text ? V.A. Kozhevnikov, S.G. Sherman, 2008, published in Yadernaya Fizika, 2008, Vol. 71, No. 11, pp. 1891–1909.     

Synthesis of unsymmetrical and regio-defined 2,3,6-quinoxaline and 2,3,7-pyridopyrazine derivatives

Differential reactivity of the amine functionality in a number of common 1,2-diamine starting materials is exploited to undertake an expedient synthesis of unsymmetrical 2,3,6-trisubstituted quinoxaline and unsymmetrical 2,3,7-trisubstituted pyridopyrazine derivatives.     

Enzymatic assembly of the bis-indole core of rebeccamycin

Rebeccamycin is a member of the family of indolocarbazole antibiotics with broad spectrum antitumor activity. The indolocarbazole framework is derived from two molecules of tryptophan, but very little is known about the enzymes involved in rebeccamycin biosynthesis. Here, we show that RebD is responsible for all catalytic steps forming the central pyrrole ring of chlorochromopyrrolic acid from two molecules of chloroindolepyruvic acid. This transformation does not require any additional cofactors and constitutes the first step of bis-indole formation in the biosynthesis of rebeccamycin.