A theoretical insight on the halogen and hydrogen bonding interactions in the solid state structures of mononuclear zinc(II) complexes with salen type Schiff base ligands

In this manuscript we report the synthesis of two new zinc(II) complexes, [ZnL1(H2O)] (1) and [ZnL2(DMSO)] (2), characterized by elemental and spectral analysis {H2L1 and H2L2 are the tetradentate symmetrical salen-type, di-Schiff base ligands}. The structures have been confirmed by single-crystal X-ray diffraction analysis. The coordination polyhedron around the zinc(II) centers are elongated (4 + 1) square pyramid and distorted trigonal bipyramidal with ZnN2O3 chromophore, furnished by two imine nitrogen atoms and two phenolate oxygen atoms of the deprotonated Schiff base ligand, forming the basal plane; and an oxygen atom from a water molecule (in complex 1) or a DMSO molecule (in complex 2) occupying the apical position of zinc(II) center. Complex 1 forms strong self-assembled 1-D chain in the solid state. In contrast, complex 2, that incorporates DMSO in the coordination sphere, forms halogen bonding assemblies. Both types of interactions have been analyzed using DFT calculations and a variety of computational tools (MEP, NBO, QTAIM and NCIplot).