Vibrational spectra and molecular structure of isomeric 1-(adamantan-1-ylcarbonyl)-3-(dichlorophenyl)thioureas

1-(adamantan-1-ylcarbonyl)-3-(2,3-dichlorophenyl)thiourea, 1, and 1-(adamantan-1-ylcarbonyl)-3-(2,5-dichlorophenyl)thiourea, 2, were synthesized in reasonable yields from admanantyl-1-carbonyl chloride and ammonium thiocyanate followed by treatment of the resulting adamantane-1-carbonylisothiocyanate with the 2,3- and 2,5-dichloroanilines. A complete vibrational analysis was performed on the basis of FTIR and Raman spectra. The formation of intramolecular N-H center dot center dot center dot O and intermolecular N-H center dot center dot center dot S hydrogen bonds in the solids affect vibrational modes, with low frequency values observed for the nu(C = O) and nu(C = S) stretching modes. Structural data obtained by single-crystal X-ray diffraction at low temperature confirm this picture. Compound 1 crystallizes in the triclinic system and compound 2 crystallizes with two unique molecules in the asymmetric unit of the orthorhombic unit cell. The molecular structures reveal that the carbonylthiourea units in 1 and both molecules of 2 are planar due in part to the formation of intramolecular N-H center dot center dot center dot O = C hydrogen bonds that generate S (6) rings. Moreover, the crystal structures are stabilized by an extensive series of classical and non-classical hydrogen bonds and, in the case of 1 by an intermolecular Cl center dot center dot center dot Cl halogen bond. (C) 2016 Elsevier B.V. All rights reserved.