Base properties of H2CO in the excited (3)n -> pi* state

摘要

Calculations using the coupled-cluster method with singles and doubles based on a restricted open Hartree-Fock reference (ROHF-CCSD) with the aug'-cc-pVDZ basis set have been carried out to investigate the structures, energies, and vibrational spectra of protonated H2CO and of the hydrogen-bonded complexes of H2CO with HF in the excited (3)n --> pi* state. Two protonated isomers, H3CO+ and H2COH+, exist in the (3)n --> pi* state and are separated by an appreciable barrier. The carbon-protonated species H3CO+ has a computed proton affinity (Delta H-298) of 161.7 kcal/mol and is 12.9 kcal/mol more stable than the O-protonated isomer. Two complexes of H2CO with HF exist on the triplet potential surface, with binding enthalpies (Delta H-0) of - 2.8 and - 2.3 kcal/mol for the complexes hydrogen-bonded at O and C, respectively. The barrier to HF transfer from C to O is less than 1 kcal/mol. (C) 2000 John Wiley & Sons, Inc. [References: 17]