In this work we have synthesized and characterized a new HgII complex [Hg(HL)(NCS)2]2, fabricated from Hg(NCS)2 and 3-pyridinecarbaldehyde nicotinoylhydrazone (HL). Single-crystal X-ray crystallography reveals the formation of a dinuclear heteroleptic discrete structure with half of the molecule, [Hg(HL)(SCN)2], in the asymmetric unit. The ligand HL coordinates the HgII center in an unexpected monodentate fashion via the pyridine nitrogen of the nicotinic moiety. Molecules are aggregated through intermolecular N–H∙∙∙N hydrogen bonds and additional weak Hg∙∙∙N interactions. Molecules of complex aggregate into a 2D supramolecular layer with a four-connected uninodal sql (Shubnikov tetragonal plane net) topology due to intermolecular N–H∙∙∙N hydrogen bonds. When the Hg∙∙∙N interactions are excusively considered, a similar layer is formed revealing a three-connected uninodal hcb (Shubnikov hexagonal plane net) topology. Further considering both the intermolecular N–H∙∙∙N hydrogen bonds and Hg∙∙∙N interactions, the structure of complex can be extended into a 3D supramolecular framework with an eight-connected uninodal bcu (body centered cubic) topology. We have also applied DFT calculations as well as MEP, QTAIM, NCI and NBO analyses to shed light on interactions in the crystal structure of the complex. Among others, reciprocal n → π* interactions between the nitrogen lone pairs and empty antibonding π* C–N orbitals of the NCS– anions have been determined.
