Stability, properties, and electronic g tensors of the H2COH radical

For the H2COH radical, properties such as geometries, frequencies, electric and magnetic dipole moments, electronic and ionization spectra, etc., were investigated at the ab initio level (second-order Moeller-Plesset and multireference configuration interaction (MRD-CI) methods). At equilibrium, H2COH (sigma(2) pi(2)n(2) pi*) is of C-1 symmetry. The inversion and rotation conformations are about 1 and 5 kcal/mol less stable. The MRD-CI vertical ionization potentials (eV) lie at 7.89 (pi* --> infinity) and 12.91 (n --> infinity, into 1(3)A " of the cation). The pi* --> 3s state (adiabatically at T-e approximate to 3.23 eV, calculated) is placed about 1 eV lower than previously assumed. Experimental T-0's of 4.34 and 5.09 eV are respectively reassigned to pi* --> 3p(z) and pi* --> 3p(x) (perpendicular and parallel bands relative to the CO bond). At the equilibrium geometry, the valence states lie at 6.46 (n --> pi*), 7.30 (pi --> pi*), and 8.40 eV (sigma --> pi*); i.e., the latter lies in the ionization continuum. The direction of the electric dipole moment of H2COH is mainly governed by the OH bond. The electron-spin magnetic moment (g factor) was evaluated via a perturbative approach complete to second order, using a Breit-Pauli Hamiltonian. The largest second-order contributions to Delta g are due to sigma --> pi* and n --> pi*. At the ROHF level, Delta g(av) = g(av) - g(e) is similar to 500 ppm for both the equilibrium and inversion conformations and near 300 ppm for the rotation geometry. Correlated values are estimated: to be similar to 150 ppm higher. Experimental studies for H2COH in solution find Delta g(av) approximate to 1000 ppm.