Abstract
The experimental charge density study of salicylaldehyde thiosemicarbazone (SalTSC) has been performed. The analysis of the crystal packing revealed that the sulfur atom is simultaneously engaged in six hydrogen bonding interactions, two of N-H…S, leading to a dimmer, and four of C-H…S type. It has been established that the deformation density of the free electron pairs on the sulfur atom is inhomogeneously distributed within a torus. A relationship found between the deformation of the torus and the space directionality of the surrounding donor groups suggests that the sulfur atom of the thioureide moiety easily adjusts to the environment in order to increase the number of stabilizing contacts. CSD study of the compounds containing thioureido -N-C(=S)-N fragment confirmed the experimental results for SalTSC, i.e. about 60% of the analyzed crystal structures form dimer trough N-H…S interactions while in about 50% of crystal structures the S atom forms four of more D-H…S intermolecular interactions (D = C, N and O).