Coordination geometry isomerism induced by N–H⋯Cl, C–H⋯Cl, C–H⋯N, C–H⋯π and π⋯π supramolecular interactions in mercury(II) complexes with tripyridylimidazole chelating ligands

Reaction of HgCl2 with trans-(±)2-(2,5-di(pyridin-2-yl)-4,5-dihydro-1H-imidazol-4-yl)pyridine (L1) and cis-(±)-(phenyl(2,4,5-tri(pyridin-2-yl)-4,5-dihydroimidazol-1- yl)methanone (L2) gives mononuclear complexes, 1 and 2. In these complexes L1 and L2 behave as tridentate and bidentate chelating ligands, giving distorted trigonal bipyramidal and tetrahedral coordination geometries, respectively. X-ray diffraction studies revealed a series of N–H⋯Cl, C–H⋯Cl, C–H⋯N and C–H⋯π interactions in 1 giving a 3D network, and N–H⋯Cl, C–H⋯Cl, C–H⋯π and π⋯π interactions in 2 giving a 2D network in the crystal lattice. Since both ligands should have a similar binding capacity to the mercury ions, the variations observed for coordination number and geometry should be a consequence of supramolecular stabilizing effects.