title: 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).
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.
authors.affiliation: Department of Chemistry, Memorial University , St. John's, Newfoundland and Labrador, Canada A1B 3X7.
authors.forename: Barry
authors.initials: B
authors.lastname: Power
authors.affiliation: Department of Chemistry, Memorial University , St. John's, Newfoundland and Labrador, Canada A1B 3X7.
authors.forename: Steven
authors.initials: S
authors.lastname: Rowe
authors.affiliation: Department of Chemistry, Memorial University , St. John's, Newfoundland and Labrador, Canada A1B 3X7.
authors.forename: Travis D
authors.identifier: 0000-0001-7625-868X
authors.initials: TD
authors.lastname: Fridgen