Synthesis, crystal structure, Hirshfeld surface analysis and DFT calculations of the coordination compound tetra-aqua-bis-{2-[(5-methyl-1,3,4-thia-diazol-2-yl)sulfan-yl]acetato-κO}cobalt(II).

A novel coordination compound, [Co(L)₂(H₂O)₄], was synthesized from aqueous solutions of Co(NO₃)₂ and the ligand 2-[(5-methyl-1,3,4-thia-diazol-2-yl)sulfan-yl]acetic acid (HL, C₅H₆N₂O₂S₂). In the monoclinic crystals (space group P2₁/c), the cobalt(II) ion is located about a centre of symmetry and is octa-hedrally coordinated by two L^- anions in a monodentate fashion through carboxyl O atoms and by four water mol-ecules. A relatively strong hydrogen bond between one of the water mol-ecules and the non-coordinating carboxyl-ate O atom consolidates the conformation. In the crystal, inter-molecular hydrogen bonds lead to the formation of a complex tri-periodic structure. Hirshfeld surface analysis revealed that 30.1% of the inter-molecular inter-actions are from H⋯H contacts and 20.8% are from N⋯H/H⋯N contacts. DFT calculations were performed to assess the stability and chemical reactivity of the compound by determining the energy differences between the HOMO and LUMO.