Structures of electrosprayed Pb(Uracil-H) + complexes by infrared multiple photon dissociation spectroscopy

Abstract

The structures of three ion molecule complexes of [Pb(Ura-H)] + have been explored by infrared multiple photon dissociation (IRMPD) spectroscopy in the gas phase. A complex of [Pb(Ura-H)] + with uracil, [Pb(Ura-H)(Ura)] +, or the singly or doubly water solvated complexes, [Pb(Ura-H)(H 2O)] + and [Pb(Ura-H)(H 2O) 2] +, have been irradiated with tunable infrared radiation in the N–H/O–H stretching region (3200–4000 cm −1) to produce IRMPD spectra which were compared with IR spectra computed using B3LYP/6-31+G(d,p) for various isomers. In all cases, the computed spectra for the lowest energy structures agree very well with the experimental IRMPD spectrum. Results show that all complexes involved a [Pb(Ura-H)] + core which is deprotonated at N3 and has lead bound to either N3 and O4 or N3 and O2. Our results suggest that the [Pb(Ura-H)] + structure that is deprotonated at N1 and lead is bound to N1 and O2 is not an significant contributor to the electrosprayed complexes. [Pb(Ura-H)(Ura)] + was found to have a four-coordinate lead. The water molecules in [Pb(Ura-H)(H 2O)] + and [Pb(Ura-H)(H 2O) 2] + were determined to be directly coordinated to lead, the first also hydrogen bonded to one carbonyl oxygen.