Crystallographic and PM3-COSMO SCF-MO study of the structure and properties of aryloxy- or arylthio-thiazinones

Abstract

The solid state structures of three para-substituted aryloxy- or arylthio-thiazinone derivatives reveal that the conformation of 2 differs from 1 and 3 in the orientation of the Y–aryl bond, due in part to an unusually strong CO ⋯ H–C–S intermolecular interaction of r_{O ⋯ H} 2.20 Å present in 2. A search of the Cambridge crystal structure database revealed relatively few other structures with similarly strong O ⋯ H–C interactions in which the common feature is the H–C–S structural unit. The observed reaction rate for aqueous hydrolysis of this series of compounds via attack of water at the C(2) position was found to correlate with the energy of the highest unoccupied orbital corresponding to σ rather than π character, but no feature in the wavefunctions could be found which identified 2 as the most likely to form the strongest O ⋯ H–C–S hydrogen bonding interaction in this series.