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A Comparative IRMPD and DFT Study of Fe3+ and UO22+ Complexation with N‑Methylacetohydroxamic Acid
journal contribution
posted on 2018-01-16, 18:46 authored by Thibault Terencio, Jana Roithová, Stéphane Brandès, Yoann Rousselin, Marie-José Penouilh, Michel MeyerIron(III) and uranyl
complexes of N-methylacetohydroxamic acid (NMAH)
have been investigated by mass spectrometry, infrared multiphoton
dissociation (IRMPD) spectroscopy, and density functional theory (DFT)
calculations. A comparison between IRMPD and theoretical IR spectra
enabled one to probe the structures for some selected complexes detected
in the gas phase. The results show that coordination of Fe3+ and UO22+ by hydroxamic acid is of a very
similar nature. Natural bond orbital analysis suggests that bonding
in uranyl complexes possesses a slightly stronger ionic character
than that in iron complexes. Collision-induced dissociation (CID),
IRMPD, and 18O-labeling experiments unambiguously revealed
a rare example of the UO bond activation concomitant with
the elimination of a water molecule from the gaseous [UO2(NMA)(NMAH)2]+ complex. The UO bond
activation is observed only for complexes with one monodentate NMAH
molecule forming a hydrogen bond toward one “yl” oxygen
atom, as was found by DFT calculations. This reactivity might explain
oxygen exchange observed for uranyl complexes.