THE M(O-2)X(YH3)(3) DIOXYGEN COMPLEXES (M = RH, CO - X = F, CL, BR, I- Y = N, P) - AN AB-INITIO, DFT AND SEMIEMPIRICAL PM3(TM) STUDY

The molecular structure, energetics and vibrations have been calculate d for the MO2 moiety in the M(O-2)X(YH3)(3) series of metal dioxygen c omplexes at three levels of theory: nb initio (RHF/3-21G*), DFT (B3PW 91/3-21G*) and semiempirical PM3(tm). The methods yielded the O-O dis tances consistent with the experimental values and similarly predicted the tendencies of geometrical parameters to change. The variation of the enthalpy of formation with the central metal atom, halogen and lig and seems to be in qualitative interconsistency, whereas changes in th e MO2 moiety frequencies, found at different levels, disagree substant ially.