AB-INITIO AND MOLECULAR MECHANICS STUDIES OF THIANTHRENE AND SIMILAR MOLECULES

The structures of six molecules (dibenzodioxine, phenoxathiin, thianth rene, 1-azathianthrene, 1,4-diazathianthrene and 1,4,6,9-tetraazathian threne) previously studied by X-ray and electron diffraction have been calculated using MM3 and ab initio (3-21G basis set) methods. These computational methods reproduce correctly the experimental bond length s, bond angles and conformations. Calculations helped to classify all the molecules into two families, where the thianthrene is a common mem ber of both. The calculated barriers to planarity are found to correla te with both the calculated and the observed puckering angles of the m olecules. (C) 1997 Elsevier Science B.V.