Modeling the interaction of the phosphate group in nucleotides with copper(I) in the gas phase: Reactivity of Cu+ with orthophosphoric acid and its monomethyl ester

The gas-phase reactivity of orthophosphoric acid (HO)(3)P=O with the cation Cu+ has been investigated through the use of mass spectrometry experiments and DFT calculations. Its monomethylated ester (CH3O)(HO)(2)P=O has been a lso theoretically studied at the same level in order to take into account t he possible effects of methylation. Computational results, including struct ural features, vibrational frequencies, and binding energies, obtained with the hybrid three-parameter B3LYP density functional combined with relativi stic ECPs and associated valence basis set, were reported. Final binding en ergies have been evaluated using extended basis sets. Additional calculatio ns performed with several "all electron" basis sets are also included for c omparison. For some of the minima of the [Cu,H3PO4](+) hypersurface, the na ture of the different Cu-O bonds as well as the character of the orbitals i nvolved were analyzed by means of the Bader topological analysis and NBO me thod.