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Accueil du site > Production scientifique > 145 . Ammoniated Complexes of Uracil and Transition Metal Ions : Structures of [M(Ura-​H)​(Ura)​(NH3)​]​+ by IRMPD Spectroscopy and Computational Methods (M = Fe, Co, Ni, Cu, Zn, Cd)

145 . Ammoniated Complexes of Uracil and Transition Metal Ions : Structures of [M(Ura-​H)​(Ura)​(NH3)​]​+ by IRMPD Spectroscopy and Computational Methods (M = Fe, Co, Ni, Cu, Zn, Cd)

Date de publication: 16 décembre 2016

B. Power ; S. Rowe ; T. D. Fridgen
J. Phys. Chem. B 121 (1) 58-65 (2017). DOI

Travail réalisé sur le site de l’Université Paris Sud.

Abstract

The structures of deprotonated d-block metal dication bound uracil dimers, solvated by a single ammonia molecule, were explored in the gas phase using infrared multiple photon dissociation (IRMPD) spectroscopy in a Fourier transform ion cyclotron resonance–mass spectrometer. The IRMPD spectra were then compared with computed IR spectra for various isomers. Calculations were performed using B3LYP with the 6-31+G(d,p) basis set for all atoms, with the exception of Cd, for which the LANL2DZ basis set with relativistic core potentials was used. The calculations were then repeated using the def2-TZVPP basis set on all atoms and were compared to the first set of calculations. The lowest-energy structures are those in which one uracil is deprotonated at the N3 position and, aside from the Cu complex, the intact uracil is a tautomer in which the N3 hydrogen is at the O4 carbonyl oxygen. The metal displays a tetradentate interaction to the uracil moieties, with the exception of Cu, which is tridentate, and the ammonia molecule is bound directly to the metal center. In the Cu complex, a square planar geometry is observed about the metal center, consistent with Jahn–Teller distortions commonly observed in Cu(II) complexes, and the intact uracil assumes its canonical tautomer. All other metal cation complexes are five-coordinate, square pyramidal complexes, with the intact uracil adopting a tautomer in which the N3 hydrogen is on O4. The IRMPD spectroscopic data are consistent with the computed infrared spectra for the lowest-energy structures in all cases.