Electronic isomers in [(CO2)nROH]- cluster anions. II. Ab initio calculations

Ab initio MO calculations have been performed for the [(CO2)n,ROH]- (R = H and CH3) anions with n = 1 and 2. Three stable structures are found for [(CO2)H2O]-, and two structures for [(CO2)CH3OH]-. All the [(CO2)ROH]- structures are characterized by the charge localization on the CO2 moiety, which interacts with ROH through an O-H [midline ellipsis] O linkage. It is also revealed that the addition of ROH to CO-2 leads to the formation of a potential barrier against autodetachment higher than that of a bare CO-2, which results in the increasing stability of [(CO2)ROH]- species. For n = 2 the calculations predict the existence of two types of isomers having different degrees of the excess electron localization: CO-2·ROH(CO2) and C2O-4·ROH isomers. These electronic isomers are calculated to be close in energy, while their calculated vertical detachment energies (VDEs) differ by more than 1 eV. The ab initio results are discussed in comparison with recent experimental ones derived from photoelectron spectra of [(CO2)nROH]-. © 1999 American Institute of Physics.