RESUMO
The synthesis and structural characterization of the hitherto unknown parent Co(bz)2+ (bz=benzene) complex and several of its derivatives are described. Their synthesis starts either from a CoCO5+ salt, or directly from Co2 (CO)8 and a Ag+ salt. Stability and solubility of these complexes was achieved by using the weakly coordinating anions (WCAs) [Al(ORF )4 ]- and [F{Al(ORF )3 }2 ]- {RF =C(CF3 )3 } and the solvent ortho-difluorobenzene (o-DFB). The magnetic properties of Co(bz)2+ were measured and compared in the condensed and gas phases. The weakly bound Co(o-dfb)2+ salts are of particular interest for the preparation of further CoI salts, for example, the structurally characterized low-coordinate 12 valence electron Co(Pt Bu3 )2+ and Co(NHC)2+ salts.
RESUMO
The facile synthesis of a pentacarbonyl cobalt(I) salt without the need for a superacid as solvent is presented. This salt, [Co(CO)5 ]+ [Al(ORF )4 ]- {RF =C(CF3 )3 }, readily accessible on a multigram scale, undergoes substitution reactions with arenes yielding the hitherto unknown class of two-legged cobalt piano-stool complexes [(arene)Co(CO)2 ]+ with four different arene ligands. Such a substitution chemistry would have been impossible in superacid solution, as the arenes used would have been oxidized and/or protonated. Thus, the general approach described herein may have a wide synthetic use. Additionally, the thermochemistry of the piano-stool complexes is shown to be not easy to describe computationally and most of the established DFT methods overestimate the reaction energies. Only CCSD(T) calculations close to the basis set limit gave energies fully agreeing with the experiment.
RESUMO
Molecular manganese fluorides were studied using quantum-chemical calculations at DFT and CCSD(T) levels and experimentally by matrix-isolation techniques. They were prepared by co-deposition of IR-laser ablated elemental manganese or manganese trifluoride with F2 in an excess of Ne, Ar, or N2 or with neat F2 at 5-12 K. New IR bands in the Mn-F stretching region are detected and assigned to matrix-isolated molecular MnFx (x = 1-3).
RESUMO
Neste estudo os autores revisam os principais aspectos de raquianestesia
Assuntos
Humanos , Anestésicos/uso terapêutico , Raquianestesia , Anestésicos/administração & dosagem , Raquianestesia/efeitos adversos , Raquianestesia , Bradicardia/etiologia , Cefaleia/etiologia , Hipotensão/etiologia , Fatores de TempoRESUMO
Os autores visam descrever e comparar as principais técnicas de analgesia no pós-operatório de cirurgia torácica
