Zinc and manganese complexes with 4-aminoantipyrine

The interaction of 4-aminoantipyrine (aap) with metal(II) pseudohalides [M = Zn and Mn] in aqueous media resulted in three new complexes; [Zn(aap)(N3)2(H2O)]n (1), [Zn(aap)3][Zn(NCS)4]·1/2H2O (2), and [Mn(aap)2(NCS)2] (3). The structure of 1 reveals μ1,3-bridging azido groups connecting zinc centers to form 1D chains of polyhedra oriented along the c-axis of the monoclinic unit cell. The zinc(II) center is octahedrally coordinated by O(1) and N(1) of bidentate N,O chelating aap molecule, by N(11) and N(13) of μ1,3-bridging azido group, N(21) of a terminal azido group, and O(2) of aqua ligand, resulting in a ZnN4O2 geometry. The structure of complex 2 consists of [Zn(aap)3]2+ complex cations, [Zn(NCS)4]2− complex anions and disordered lattice water molecules. The structure of 3 reveals mononuclear complexes, where the Mn(II) centers are ligated by the exocyclic N and O donor atoms of two chelating aap molecules and two N atoms of terminal isothiocyanato ligands. Thermal properties and IR spectra of the complexes were investigated and shown to be consistent with the structures.

► 1D zinc azido bridged chain containing bridging μ1,3-N3- and terminal azide [Zn(aap)(N3)2(H2O)]n (1).
► Structural investigations support the chelating binding mode of aap ligand rather than terminal binding mode.
► Different binding behavior of thiocyanato ligands in [Zn(aap)3][Zn(NCS)4]·1/2H2O (2), and [Mn(aap)2(NCS)2] (3) complexes.
► Hydrogen bonds connect 1D polymeric chain to supramolecular networks.