A straightforward and novel synthesis of sulfur compounds from aliphatic cyclic ketones and CS2

The reaction of aliphatic cyclic ketones with carbon disulfide under basic conditions, followed by an acidic treatment, unexpectedly afforded—in a mild, one‐pot reaction—sulfur compounds, such as 1,2‐dithiole‐3‐thiones, 1,3‐dithiole‐4‐thiones, 1,3‐dithiin‐4‐thiones, 1,2,4‐trithioles, and dixanthates, instead of the usual conjugated α‐oxoketene dithiolic acids. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:120–128, 2000     

Mechanism of the OH–propene–O2 reaction: An ab initio study

The reaction of OH radicals with olefins is known to be important in atmospheric chemistry. From experimental data a global mechanism has been proposed, but the regioselectivity of the products is uncertain. In this work, the OH–propene–O₂ reaction has been studied with ab initio molecular orbital techniques. Reactants, transition structures, intermediate species and products are optimized at the UMP2/6‐31G** level for the two possible addition paths. In the first step, OH adducts are obtained with the OH radical linked to either the terminal or the central C atoms. Consideration of the second step, the addition of O₂, is required to explain the observed experimental data. The selectivity of the total reaction is found to be temperature and pressure dependent, but independent of the preferred site for the OH attack. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet: 31: 29–36, 1999     

Signature inversion in πi13/2⊗νi13/2 structure in 178Ir

High-spin states in ¹⁷⁸Ir were investigated by means of in-beam γ-ray spectroscopy techniques using the multidetector array GASP. Excited states of ¹⁷⁸Ir were populated through the ¹⁵⁹Tb(²⁴Mg, 5n) fusion-evaporation reaction at E(²⁴ Mg) = 131-141 MeV. Several rotational bands were observed. Among them, the πi _13/2⊗νi _13/2 structure has been identified up to spin 36 ?. This band exhibits an anomalous signature splitting and a signature inversion around spin 25 ?. Received: 13 December 2000 / Accepted: 11 April 2001     

Structure of the odd-odd-nucleus 84Nb

The nucleus ⁸⁴Nb has been studied with the ⁵⁸Ni(²⁸Si,pnγ) reaction at 90 MeV. Several rotational structures are established and connected to an irregular low-energy level scheme which includes one isomeric level whose decay was observed before. Received: 23 July 1998 / Revised version: 30 November 1998     

Evaluation of metal complexation as an alternative to protonation for electrospray ionization of pharmaceutical compounds

The use of pyridyl and polyether compounds as auxiliary ligands to promote metal complexation of a series of pharmaceutical analytes by electrospray ionization (ESI) is explored as an alternative to conventional protonation by ESI. The auxiliary ligands vary in the number and nature of binding sites, the orientation of the binding sites with respect to each other, and the conformational flexibility of the ligand during complexation of the metal ion. The ESI of ternary solutions composed of a pharmaceutical substrate, a transition metal ion salt, and an auxiliary complexation agent generate metal complexes of the type [(L-H⁺)M^II(aux)]⁺, where L is the pharmaceutical, M is either copper, nickel, or cobalt, and aux is the auxiliary ligand. Overall, the pyridine-type ligands are more useful for the generation of ternary metal complexes than the polyether-type ligands, which preferentially complex sodium ions and, upon collisional activation, undergo fragmentation of the polyether skeleton in addition to the structurally informative dissociation of the analytes. The auxiliary ligand that exhibits the best performance is 2,2′-dipyridine; its ternary metal complexes enhance the structural characterization of five of the pharmaceuticals by promoting a greater number of fragments relative to the CAD patterns of the protonated substrates.