Abstract
We report the photoelectron spectra of anionic complexes between 1-methylcytosine (mC) and formic acid (FA) in 1 : 1 and 1:2 stoichiometries that have been measured with 2.54 eV photons. Each spectrum consists of a broad peak with maxima at 1.85 and 2.1 eV, respectively, confirming the generation of stable valence anions in the gas phase. The neutral and anionic complexes of mC(FA) and mC(FA)2 were also studied computationally at the B3LYP, second-order Møller–Plesset, and coupled-cluster levels of theory with the 6–31++G** and aug-cc-pVDZ basis sets. Based on the calculations, we conclude that the photoelectron spectra of mC(FA)− and are due to anions that originate from a barrier-free proton transfer (BFPT) triggered by excess electron attachment. They can be viewed as neutral radicals of hydrogenated 1-methylcytosine solvated by a deprotonated formic acid.
Acknowledgements
The experimental part of this work was supported by the National Science Foundation under grant No. CHE-0809258 (K.H.B.), and the theoretical parts were supported by the Polish State Committee for Scientific Research (KBN), grants KBN/N N204 023135 (J.R.) and DS/8221-4-0140-8 (P.S.), and by the U.S. Department of Energy under contract DE-AC02-05CH11231 and through a 2008 Seaborg Fellowship at Lawrence Berkeley National Laboratory (M.H.). The calculations were performed at the Academic Computer Center in Gdańsk (TASK).