resumo
Organoazides are intermediates in the synthesis of imidometal complexes. Metalimido complexes have an important role in catalysis. Thus, the organoazide interaction with metals is an important issue. However, the isolation of organoazidometal complexes is difficult due to the easy loss of N-2. The present study describes the complexation of nickel by nitrobenzyl azides by means of electrospray ionization mass spectrometry (ESI-MS), which was used also as a probe for the characterization of isomers. Organoazidometal complexes were observed and isolated from solutions of NiCl2 and NiBr2 in methanol/water. A different solvent, ethanol/water was also used. The complexes detected were singly and doubly positively charged, with various stoichiometries. The most abundant species were [Ni(II)Az(3)](2+) for ortho- and para-isomers, and [Ni(II)Az(3)(H2O)](2+) for meta isomer, where Az stands for nitrobenzyl azides. The ortho isomer showed several single positively charged complexes integrating chloride as a ligand. The mass spectra of the three isomers allowed their differentiation based on different behaviour in the mass range m/z 296 m/z 312. The MS2 spectra of [Ni(II)Az(3)](2+) were investigated aiming to characterize the three isomers but this analysis was not absolutely conclusive about the coordination site(s). Density functional theory calculations provided possible structures for the [Ni(II)Az(3)](2+) cation with the different isomers and their coordination modes could be responsible for their fragmentation pathways. (C) 2013 Elsevier B.V. All rights reserved.
palavras-chave
IONIZATION MASS-SPECTROMETRY; EFFECTIVE CORE POTENTIALS; TRANSITION-METAL-COMPLEXES; 2-ALKYNYL BENZYL AZIDES; ELECTROSPRAY-IONIZATION; ORGANIC AZIDES; ALKYNE CYCLOADDITION; MOLECULAR CALCULATIONS; COORDINATION CHEMISTRY; IMIDOMETAL COMPLEXES
categoria
Physics; Spectroscopy
autores
Cunha, BMP; Trindade, IN; Couto, NAS; Costa, PJ; Rodrigues, P; Barros, MT; Costa, ML; Duarte, MF; Fernandez, MT; Madeira, PJA
nossos autores
Paulo Jorge Ferreira de Matos Costa
Bolseiro de pós-DoutoramentoGrupos
agradecimentos
The NMR spectrometer is part of The National NMR Network (REDE/1517/RMN/2005) and the Fourier Transform Ion Cyclotron Resonance Mass Spectrometer is part of the National Mass Spectrometry Network (REDE/1501/REM/2005), supported by