Conformational and crystal structure of acyl thiourea compounds: The case of the simple (2,2-dimethyl-propionyl) thiourea derivative

A novel and simple compound from the family of 1-acyl thioureas, namely (2,2-dimethyl-propionyl) thiourea (also named as N-carbamothioyl pivalamide), has been prepared. It has been fully characterized by microelemental analysis, FTIR, multinuclear (1H and 13C) NMR and mass spectroscopy, and the crystal structure determined by using single crystal X-ray diffraction study. Intramolecular N–H⋯OC hydrogen bond occurs between the carbonyl (CO) and thioamide (–NH2) groups forming a S6 pseudo-ring that stabilize the conformation. The Natural Bond Orbital (NBO) population analysis demonstrates that the hyperconjugative remote interaction between the donor lone pairs located on the carbonyl oxygen and the N–H group, i.e. lpO → σ∗(N–H) is responsible for the preferred conformation. Intermolecular interactions in the crystal are characterized by hydrogen-bonding networks between the carbamide (NH2) groups and the thiocarbonyl bond (CS), including R22(8) dimer motifs promoted by the N–H⋯SC synthon. Hirshfeld surface analysis was performed for visualizing, exploring and quantifying intermolecular interactions present in the crystal structure.