A theoretical study of the photodetachment and intramolecular hydrogen-bonding energies of hydrogen maleate anions.
Three low-lying conformers of the hydrogen maleate anions (HMAs) regarding cis-HMA(HB) having the O-...HO intramolecular hydrogen bond (HB), cis-HMA(nHB) without the HB, and trans-HMA are studied by density functional theory (B3LYP) combined with natural bond orbital (NBO) and atoms-in-molecules (AIM) analyses. The photoelectron spectra of cis- and trans-HMA conformers recorded by Woo et al. (J. Phys. Chem. A 2005, 109, 10633) are reassigned on the basis of the present electron propagator theory calculations, indicating the significant energy differences between the Dyson orbitals and canonical molecular orbitals due to the electron-correlation and orbital relaxation effects considered in the electron propagator theory. The NBO associated with the natural resonance theory analyses and AIM electron topological study show that the strong O-...HO in cis-HMA(HB) has the remarkable characteristics of three-center four-electron hyperbond, and the bonding strength of ca. 30 kcal/mol is recommended with the reference calculations of the HO-...HOH complex. The further calculations for the microhydrated cis-HMA(HB) clusters indicate that the O-...HO bonding strength decreases in water solution.
Tian
Shan Xi
SX
Hefei National Laboratory for Physical Sciences at Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China. sxtian@ustc.edu.cn
Li
Hai-Bei
HB
D000838:Anions; D006860:Hydrogen Bonding; D008298:Maleates / Q000737:chemistry*; D008962:Models, Theoretical; D010777:Photochemistry
D000838:Anions; D008298:Maleates; C030272:maleic acid