ABSTRACT
An integrated quantum mechanical approach for the structural, vibrational, and magnetic characterization of free radicals in the gas phase and in solution is introduced and validated for a set of representative systems. Hyperfme couplings computed by hybrid density functionals are in fair agreement with experiment and their reliability is significantly improved by combining CCSD(T) equilibrium values with vibrational corrections obtained at the DFT level. Experimental values in aqueous solution are then recovered using a mixed discrete-continuum solvent model. The g-tensors computed by hybrid density functionals are reasonably accurate and show a small dependence on the specific form of the density functional, the extension of the basis set over a standard 2z+polarization level, vibrational averaging, and bulk solvent effects. However, hydrogen bridges with solvent molecules belonging to the first solvation shell play a significant role.
