Pulsed field ionization electron spectroscopy and molecular structure of aluminum uracil.
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| Abstract | 
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              Al-uracil (Al-C4H4N2O2) was synthesized in a laser-vaporization supersonic molecular beam source and studied with pulsed field ionization-zero electron kinetic energy (ZEKE) photoelectron spectroscopy and density functional theory (DFT). The DFT calculations predicted several low-energy Al-uracil isomers with Al binding to the diketo, keto-enol, and dienol tautomers of uracil. The ZEKE spectroscopic measurements of Al-uracil determined the ionization energy of 43 064(5) cm-1 [or 5.340(6) eV] and a vibrational mode of 51 cm-1 for the neutral complex and several vibrational modes of 51, 303, 614, and 739 cm-1 for the ionized species. Combination of the ZEEK spectrum with the DFT and Franck-Condon factor calculations determined the preferred isomeric structure and electronic states of the Al-uracil complex. This isomer is formed by Al binding to the O4 atom of the diketo tautomer of uracil and has a planar Cs symmetry. The ground electronic states of the neutral and ionized species are 2A' ' and 1A', respectively. The 2A' ' neutral state has a slightly shorter Al-O4 distance than the 1A' ion state. However, the 1A' ion state has stronger metal-ligand binding compared to the 2A' ' state. The increased Al-O4 distance from the 2A' ' state to the 1A' state is attributed to the loss of the pi binding interaction between Al and O4 in the singlet ion state, whereas the increased metal-ligand binding strength is due to the additional charge-dipole interaction in the ion that surpasses the loss of the pi orbital interaction.  | 
        
| Year of Publication | 
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              2007 
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| Journal | 
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              The journal of physical chemistry. A 
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| Volume | 
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              111 
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| Issue | 
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              42 
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| Number of Pages | 
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              10567-73 
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| Date Published | 
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              2007 
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| ISSN Number | 
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              1089-5639 
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| URL | 
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              https://doi.org/10.1021/jp074933u 
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| DOI | 
   :  
              10.1021/jp074933u 
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| Short Title | 
   :  
              J Phys Chem A 
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