THE CLO4 RADICAL - EXPERIMENT VERSUS THEORY

The chlorine tetroxide radical and its anion have been investigated wi th unrestricted Hartree-Fock, density functional and hybrid Hartree-Fo ck/density functional methods, perturbation theory, and coupled cluste r methods. It is predicted that the minimum on the ClO4 radical potent ial energy surface corresponds to the B-2(2) ground electronic state, a C-2v-symmetry structure. The C-3v structure identified experimentall y lies a few kcal mol(-1) higher energetically. A C-s symmetry structu re lies very close energetically to the C-2v minimum at some levels of theory. Adiabatic electron affinities, equilibrium geometries, harmon ic vibrational frequencies, infrared intensities, isotopic shifts, and dipole moments are presented for all methods. Comparisons with recent experimental vibrational data for the radical are made. It is predict ed that the C-2v equilibrium geometry of the ground state is R(e(Cl-O1 ))=1.502 Angstrom, R(e(Cl-O2))=1.424 Angstrom, theta(e1)=93.6 degrees and theta(e2)=114.2 degrees. The adiabatic electron affinity of the Cl O4 radical is predicted to lie near 5.2 eV. (C) 1997 American Institut e of Physics.