Protonation of ferrocene in the gas phase

AbstractHydrogen-deuterium exchange, proton and deuteron transfer, and collision-induced dissociation experiments involving protonated ferrocene, [Fe(c-C5H5)2]H+, and isotopically labeled analogues have been carried out using a Fourier transform ion cyclotron resonance (FTICR) spectrometer and double-focusing mass spectrometer of reversed geometry. These experiments reveal that the structure in which the added proton is bound to one of the cyclopentadienyl rings, possibly via agostic interaction with the iron atom, plays an important role in the gas-phase behavior of protonated ferrocene. It is demonstrated that extensive hydrogen atom scrambling occurs in the cyclopentadiene ring and that the extra hydrogen can also switch from one ring to the other, probably via the iron atom. An interpretation is presented which implicates slow thermal unimolecular rearrangement on the FTICR time scale from a metal-protonated form to a ring-protonated form which is higher in energy. This interpretation successfully rationalizes the current data as well as previous gas-phase measurements and is found to be in good agreement with solution and matrix isolation studies

Identification of metabolites of a substance P (NK1 receptor) antagonist in rat hepatocytes and rat plasma

Copyright 2008 Elsevier B.V., All rights reserved.The metabolism of a substance P (NK1 receptor) antagonist in rat hepatocytes and rat plasma was described. The samples were prepared for analysis by protein precipitation followed by centrifugation. It was shown that the radiochromatograms were remarkably different from that obtained with rat hepatocytes. The mass spectrometric data in the negative ion mode was obtained without TFA acid in the mobile phase. The keto acid structure was proposed based on the mass spectrometric and chromatographic data.Peer reviewe