Spectroscopic studies on n-donor +?-acceptor systems: alkylthioureas and thiocarbanilides

The donor-acceptor interactions of alkylthioureas and thiocarbanilides with halogens have been investigated in detail employing electronic and infra-red spectroscopy. Various correlations of the spectroscopic and thermodynamic data have been presented. Alkylthioureas are by far the strongest donors known, and give high equilibrium constants (10,000-40,000 1. mole–1) and enthalpies of formation (9-18 kcal mole–1). The perturbation of the various vibrational frequencies due to charge transfer have also been studied. Hydrogen bonding of thioureas with hydroxylic compounds have been reported.