h i g h l i g h t s " Protiated and deuterated crystals of 1-(diaminomethylene)thiouron-1-ium tartate were obtained. " Hydrogen bonding motifs R 1 2 (6) and R 2 2 (8) in protiated and R 2 1 (5) and R 1 2 (6) in deuterated crystals are present. " Both compounds crystallise in the non-centrosymmetric space groups and exhibit NLO properties.
a b s t r a c tThe protiated single crystals of bis[1-(diaminomethylene)thiouron-1-ium] tartate hemihydrate were grown using a solution growth technique. The deuterated single crystals of [1-(diaminomethylene)thiouron-1-ium] tartate(À) were obtained by threefold recrystallisation of protiated crystals. The protiated and deuterated compounds crystallise in the non-centrosymmetric space groups P2 1 2 1 2 and P2 1 of the orthorhombic and monoclinic systems, respectively. The conformation of the 1-(diaminomethylene)thiouron-1-ium cation in both structures is very similar and is almost planar. The double deprotonated tartate(2À) dianion in protiated crystals exhibits C 2 symmetry, while tartate(À) monoanion in deuterated crystals has C 1 symmetry. The oppositely charged components of the crystals, i.e. 1-(diaminomethylene)thiouron-1-ium cation and tartate(2À) dianion in protiated and 1-(diaminomethylene)thiouron-1-ium cation and tartate(À) monoanion, interact via different hydrogen bonding motifs: R 1 2 (6) and R 2 2 (8) in protiated and R 2 1 (5) and R 1 2 (6) in deuterated crystals forming 2:1 and 1:1 supramolecular complexes. These supramolecular complexes interact each other via NAHÁ Á ÁO or OAHÁ Á ÁO hydrogen bonds forming the 2D-layered structures. Both compounds were also characterised by IR-spectroscopy. The SHG efficiency relative to potassium dihydrophosphate (KDP) was found to be 0.77 and 0.82 for protiated and deuterated crystals, respectively.