Synthesis, crystal structure, vibrational study, optical properties and Hirshfeld surface analysis of bis(2,6-diaminopyridinium) tetrachloridocobaltate(II) monohydrate

The title organic-inorganic hybrid compound, (C5H8N3)(2) [CoCl4]center dot H2O, was synthesized by slow evaporation at room temperature. Single-crystal X-ray diffraction analysis indicates that the asymmetric unit in this compound consists of one tetrahedral geometry [CoCl4](2-), two protonated organic cations (C5H8N3)(+) and one water molecule of crystallization, all of which lie in general positions. In the crystal structure, the inorganic layers are built from tetrachloridocobaltate anions [CoCl4](2-) and free water molecules, linked together by O-H center dot center dot center dot Cl hydrogen bonds. The organic cations are intercalated between the inorganic layers via N-H center dot center dot center dot Cl hydrogen bonds and form chains through aromatic donor-acceptor interactions. Crystal cohesion is achieved through N-H center dot center dot center dot Cl, O-H center dot center dot center dot Cl, N-H center dot center dot center dot O and C-H center dot center dot center dot Cl hydrogen bonds between organic cations, inorganic anions and the water molecules building up a three-dimensional network. The functional groups present in the crystal were studied by FTIR spectroscopy. investigation of the optical properties of the compound confirmed its semiconducting properties by revealing a direct optical band gap at 1.67 eV. Photoluminescence proprieties were also reported. The three-dimensional Hirshfeld surface (3D-HS) analysis and the two-dimensional fingerprint plots (2D-FP) reveal that the structure is dominated by H center dot center dot center dot Cl/Cl center dot center dot center dot H and H center dot center dot center dot H contacts. (C) 2018 Elsevier B.V. All rights reserved.