POLARIZABILITIES OF OXAZOLES - AB-INITIO CALCULATIONS AND SIMPLE-MODELS

Ab initio, electron correlated calculations of the equilibrium geometr ies, dipole moments, and static dipole polarizabilities are reported f or 10 heteroaromatic five-membered rings: furan, oxazole, isoxazole, a ll four oxadiazoles, both oxatriazoles, and oxatetrazole. Our geometri es and dipole moments agree well with available experimental microwave determinations. The polarizabilities are expected to be accurate to w ithin 5%. Structural isomerism affects the dipole moments strongly but the dipole polarizabilities are rather insensitive to it. Uncoupled H artree-Fock calculations indicate that as much as half the polarizabil ity comes from the sigma-electrons. Simple empirical formulas based up on atom- and bond-additive models correlate the calculated polarizabil ities of 20 five-membered heteroaromatic rings (10 azoles and 10 oxazo les) quite well.