The electronic structure of aryl thiol esters

A combination of experimental data and the CNDO/2-SCF-MO method are used to evaluate the importance of d-orbitals to the electronic structure of aryl thiol esters. The thioester group is calculated to withdraw electron density through σ and 2p_π-3d_π bonding and donate by p_π-p_π bonding. Electron donating substituents para to the thiol ester group cause the latter group to accept electron density regardless of d-orbital participation.