Role of non-covalent interactions in the supramolecular architectures of mercury(ii) diphenyldithiophosphates: An experimental and theoretical investigation

The vital role of non-covalent interactions in the supramolecular organization of two mercury(II) complexes with sulfur donor ligands have been investigated. These new complexes of mercury(II) diphenyldithiophosphates were synthesized in purely aqueous media and characterized, which corresponds to [Hg(L1)2] (1) and [Hg(L2)2]n (2), {L1 = O,O-bis(4-tert-butylphenyl) phosphorodithioate and L2 = O,O-bis(3,4-dimethylphenyl) phosphorodithioate}. These complexes have been characterized by NMR (1H, 13C and 31P), IR, UV-visible, TGA and elemental analysis. The molecular structure of 1 and 2 belong to the triclinic and monoclinic system of the space group P and P21/c, respectively, as revealed by single crystal diffraction analysis. Interestingly, complex 1 consists of a monomer unit while complex 2 consists of a polymer unit with an additional Hg⋯S bond. The supramolecular network including hydrogen bonds, spodium bonds and CH⋯π interactions in both the complexes have been identified and confirmed using theoretical analysis. A thorough analysis of the Hirshfeld surface has also been carried out to examine the intermolecular contacts in the crystal structure. Bader's Quantum Theory of Atoms-in-Molecules (QTAIM) has been applied extensively in order to acquire the quantitative and qualitative insight into the physical nature of weak non-covalent interactions. Additionally, the non-covalent interactions reduced density gradient (NCI-RDG) methods support nicely the presence of such non-covalent intermolecular interactions.