The structure and reactivity of dioxygen complexes of the transition metals.- The role of vibronic coupling in the interpretation of spectroscopic and structural properties of biomolecules.- Crystal structure non-rigidity of central atoms for Mn(II), Fe(II), Fe(III), Co(II), Co(III), Ni(II), Cu(II) and Zn(II) complexes.- Complexing modes of the phosphole moiety.