During the past several decades enormous effort has been dedicated to experimental and theoretical studies of metal-radical
organic complexes. Equilibrium geometries and electron energy structure of divalent lead Pb(II) complexes with
ortho-semiquinone radicals have been calculated by generalized gradient approximation method (GGA) within density
functional theory (DFT). Optical absorption spectra were calculated within random phase approximation (independent
particles picture). Predicted substantial modification of the absorption spectra in visible infrared regions is attributed to
the atomic configuration changes and to modifications of electronic energy due to the metal-radical coupling. The results
of the calculations are discussed in comparison with available experimental data on electron spin resonance spectra of
Pb(II) with paramagnetic ortho-semiquinone ligands.