POLARIZABILITIES OF HETEROAROMATIC MOLECULES - AZINES REVISITED

Ab initio electron-correlated calculations of the equilibrium geometri es, dipole moments, and static dipole polarizabilities are reported fo r benzene and 12 heteroaromatic six-membered rings obtained from it by aza-substitution. Our geometries and dipole moments agree well with a vailable experimental microwave determinations. The polarizabilities a re in reasonable agreement with the fragmentary experimental data avai lable. Uncoupled Hartree-Fock calculations indicate that as much as ha lf the polarizability comes from the sigma-electrons. Simple empirical formulas based on atom- and bond-additive models correlate the calcul ated polarizabilities of 33 five- and six-membered heteroaromatic ring s (10 atoles, 10 oxazoles, 13 azines) quite well. The correlation impr oves significantly if systematic data of uniform quality are used. (C) 1996 John Wiley & Sons, Inc.